University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Calibration

Classification: Parameter -> Calibration

Citations 310

"Implementation Of A Generalized Standard Addition Method In A Flow Injection System Using Merging-zones And Gradient Exploitation"
Anal. Sci. 1999 Volume 15, Issue 12 Pages 1235-1240
Edvan C. Silva, Valdomiro L. Martins Valdomiro L. Martins, Alessandro F. Araújo And Mário César U. Araújo

Abstract: A novel strategy for implementing a generalized standard addition method (GSAM) in a simple two-channel flow injection (FI) system and for correcting matrix effects and spectral interferences in multicomponent analysis is described. The FI-GSAM system exploits the concentration gradients of the sample and the standard solution, requires only one standard solution per analyte and provides several addition levels using a single simultaneous injection of the sample and of each standard solution. Because the matrix effects change at every addition level, a novel mathematical model for this FI-GSAM has been derived. The method was critically evaluated for simultaneous K, Ca and Na determinations by flame photometry in synthetic samples with different ethanol or glycerol contents, added to the samples to promote matrix effects. The results show good agreement with the expected values, with the relative error and the overall relative standard deviation usually being <5% (n=5) for 2.5 -5.0 Na, 20.0 K and 1000 mg L-1 calcium. The elapsed time for the simultaneous determination of three analytes was about 2 min, consuming 400 µl of the sample and 100 µl of each standard solution.

"An Automated Flow Injection Analysis Procedure For The Determination Of Reducing Sugars By DNSA Method"
J. Food Sci. 2001 Volume 66, Issue 3 Pages 407-411
P. Ca&ntilde;izares-Mac&iacute;as, L. Hern&aacute;ndez-Garciadiego, and H. G&oacute;mez-Ru&iacute;z

Abstract: A nonenzymatic spectrophotometric method, coupled to an automatic system of standard additions, based on the reaction with 3,5-dinitrosalicylic acid (DNSA) is described. In a system based on an exhaustive reaction, sample volumes are introduced together with calibration solutions, thus the calibration is performed in a nonsegmented flow system. Homogenization of the sample/standard/carrier takes place in the calibration loop. Later, it is injected in the flow injection analysis system, where the reaction with DNSA occurs, to obtain 3,5-diaminosalicylic acid which is measured spectrophotometrically. With the proposed method, it is possible to eliminate the Rochelle: salt, sodium and potassium tartrate, phenol and sodium bisulfite of the principal reagent. Sample throughput was 11 samples/h and precision, expressed as relative standard deviation, was 2.3%.

"Flow Injection Analysis With On-line Solid Phase Extraction For Spectrophotometric Determination Of Ponceau 4R And Its Subsidiary Unsulfonated Dye In Sweets And Cosmetic Products"
Microchim. Acta 2002 Volume 138, Issue 1-2 Pages 69-76
L. F. Capit&aacute;n-Vallvey, M. C. Valencia, E. Arana Nicol&aacute;s

Abstract: An integrated solid-phase spectrophotometry/flow injection analysis (FIA) method is proposed for the determination of the synthetic colorant matter Ponceau 4R (P4R) in the presence of its unsulfonated derivative 2-hydroxy-l-[(naphthalenyl)azo] naphthalene (N2N). The procedure is based on the measurement of P4R at lambda= 508, followed by retention and pre-concentration of the low level concentration of N2N on a C-18 silica gel minicolumn and subsequent measurement of the absorbance of N2N at lambda = 508 nm after its elution. The applicable concentration range, the detection and the relative standard were the following: for P4R, from 0.30 to 20.0 mg/L; 0.052 mg/L 1.1%; and for N2N, between 0.020 to 3.0 mg/L 0.003 mg/L and 1.1%. The method was applied to the determination of small amounts of N2N present in P4R in food and cosmetic products. Percentages of recovery between 95 and 105% were obtained in all instances. The method was applied satisfactorily to the determination of the compounds P4R and N2N in samples of sweets and cosmetic products when compared to results offered by a HPLC reference method.

"Single Standard Calibration For An Optical Oxygen Sensor Based On Luminescence Quenching Of A Ruthenium Complex"
Anal. Chim. Acta 2000 Volume 403, Issue 1-2 Pages 57-65
Martin M. F. Choi and Dan Xiao

Abstract: An optical oxygen (O-2) sensor consisting tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) ditetrakis(4-chlorophenyl) borate adsorbed on silica gel has been successfully fabricated and used to continuously monitor O-2 gas at low concentration. The luminescence material shows a very strong and stable pink emission when excited by blue light and it is efficiently quenched by O-2. The calibration of the optical sensor can be simply done by a single standard flow injection method. The results demonstrate excellent linear Stern-Volmer behavior when O-2 concentration is at low levels (0.0-0.05% v/v), but the Stern-Volmer plot has a slightly downward curvature at higher O-2 levels. The two-site quenching model correlates well with the calibrated O-2 concentration range (0.0-0.55%). The t(95) response times of the sensor are <0.2 s on going from 0.0% to 0.55% O-2 and <1 s on going from 0.55% to 0.0% O-2. The sensor has high photostability a long lifetime and no hysteresis in the response.
Oxygen, molecular Fluorescence

"A Novel Chemiluminescent Method For The Determination Of Salicylic Acid In Bactericidal Solutions"
Anal. Bioanal. Chem. 2002 Volume 372, Issue 4 Pages 601-604
Hua Cui, Shifeng Li, Feng Li, Yugang Sun, Xiangqin Lin

Abstract: A new flow injection procedure has been developed for the determination of salicylic acid based on the enhancement of the chemiluminescence from the cerium(IV)-Tween 20 reaction by salicylic acid in acidic medium. The method is simple, selective and sensitive with a detection limit of 2.5 x 10^-9 g mL-1. It is applicable to the determination of salicylic acid in the concentration range of 4.0 x 10^-9 - 1.1 x 10^-6 g mL-1. The relative standard deviation (RSD) is 0.85% for 4.0 x 10^-7 g mL-1 salicylic acid (n=11). The method has been successfully applied to the determination of salicylic acid in bactericidal solutions. Furthermore, it is suggested that light emission from cerium(IV)-Tween 20 reaction is probably because of the formation of singlet oxygen O-1(2)* and the emitter is excited oxygen molecular pairs O2(1Δg)O2(1Σg-).

"Expanding The Working Concentration Range For The Direct Analysis Of Metallic Alloys By Online Anodic Electrodissolution And Electrothermal Atomic Absorption Spectrometry"
Anal. Chim. Acta 1999 Volume 401, Issue 1-2 Pages 307-315
Jos&eacute; Bento Borba da Silva, Maria Bert&iacute;lia Oss Giacomelli, Ivan Gon&ccedil;alves de Souza and Adilson Jos&eacute; Curtius

Abstract: The behavior of several absorption lines under different atomization conditions (from tube wall, Lvov platform and with and without modifier) and the maintenance of the carrier gas flow during atomization were studied with the objective of expanding the:working concentration range in the determination of Sn, Ni and Fe in brass alloy samples by online anodic electrodissolution and electrothermal atomic absorption spectrometry (ETAAS). The employment of several lines and atomization conditions does not seem to affect the precision with any of the investigated metals. The upper working limit for Sn, Ni, and Fe is approximately 1.5, 3.5 and 4.0 times higher, respectively, under stop gas flow conditions using the less sensitive line than under the most sensitive condition. When combined with the use of resonance lines, non-stop gas flow could be a promising alternative especially for Ni and Fe. The use of non-stop gas flow in combination with non-resonance lines should be avoided, The detection limit and the sensitivity can be adjusted better, by employing elevated currents in the electrodissolution step.

"An Enzyme Thermistor-based Assay For Total And Free Cholesterol"
Clin. Chim. Acta 1999 Volume 289, Issue 1-2 Pages 145-158
Venkatesh Raghavan, Kumaran Ramanathan, P. V. Sundaram and Bengt Danielsson

Abstract: A method to evaluate the free (FC) and total cholesterol (TC) in human serum, bile and gallstone extract using an enzyme thermistor (ET)-based flow injection analysis (FIA) is presented. The cholesterol in high-density (HDL-C) and low density lipoprotein (LDL-G) have also been evaluated. A heparin functionalized Sepharose column was employed for the isolation of HDL and LDL fractions from serum. The estimation of cholesterol and its esters was based on their reaction with cholesterol oxidase (GO), cholesterol esterase (GE) and catalase (CAT). Three different enzyme columns, i.e. co-immobilized CO/CAT (column A), only GE (column B) and co-immobilized CO/CE/CAT (column C) were prepared by cross-linking the enzymes on glass beads using glutaraldehyde. Column A was used for estimating FC and column C was used for estimating total cholesterol (cholesterol plus esterified cholesterol). Column B was used as a pre-column which could be switched in or out in conjunction with column A for the estimation of TG or FC, respectively. A calibration between 1.0 and 8.0 mmol/l for FC and 0.25 and 4.0 mmol/l for TC was obtained. For more than 2000 assays with the ET device a CN. of less than 4% was obtained. The assay time was approximately 4 min per assay. The cholesterol estimations on the ET correlated well with similar estimations using a commercially available cholesterol diagnostic kit.

"The Influence Of Diffusion Fluxes On The Detection Limit Of The Jalpaite Copper Ion-selective Electrode"
Electroanalysis 2002 Volume 14, Issue 7-8 Pages 493-498
Alberto Zirino, Roland De Marco, Ignacio Rivera, Bobby Pejcic

Abstract: It has been suggested that electrode dissolution and the concomitant saturation of the electrodes diffusion layer restricts the detection limit of the jalpaite Cu ion-selective electrode (ISE) to samples with total Cu levels above 10^-6 mol L-1 [1, 2]. This article will use rotating disk electrode (RDE) data for San Diego Bay seawater and Ficks law of diffusion to demonstrate that the static commercial Orion Cu ISE (employing a jalpaite membrane) produces a background level of contamination of (2.0±0.5) x 10^-8 mol L-1 total Cu, and the reduced thickness of the Orion Cu ISEs diffusion layer in the presence of hydrodynamic flow [e.g., at an RDE, or in continuous flow analysis (CFA)] lowers the background contamination of Cu to <10^-9 mol L-1. Furthermore, the RDE Cu ISE employing an electrode fabricated using jalpaite precipitated in 80% excess Na2S, so as to minimize the presence of occluded and leachable Cu2+ salts and extraneous phases such as silver sulfide [3 - 5], reveals an improvement in the lower limit of detection compared to the commercial Orion Cu ISE.

"Performance Characteristics For Flow Injection Immunoassay Using Monoclonal Antibodies Against S-triazine And 2,4-D Herbicides"
Anal. Chim. Acta 2000 Volume 412, Issue 1-2 Pages 19-27
Milan Fr&aacute;nek, Anping Deng and Vladim&iacute;r Kol&aacute;&#345;

Abstract: A sequential injection instrument (ALITEA, USA) with a photometric and fluorometric detection unit S2000 (Ocean Optics) was employed for the development of flow injection immunoanalysis (FIIA). The monoclonal antibodies against atrazine, simazine and 2,4-D were immobilized on aminopropyl glass particles by means of avidin/biotin system and packed in plexiglass column of 18 µl volume. Assay characteristics for individual antibody-reactors and regeneration effectivities for acid and alkaline solutions are described. An attempt to prepare a functional mixed antibody-reactor has not achieved success since regeneration conditions found for individual reactors were not compatible with one performance protocol.
Atrazine Simazine 2,4-Dichlorophenoxyacetic acid Environmental Spectrophotometry Fluorescence

"Comparison Of Spectrophotometric And Potentiometric Detection For The Determination Of Water Using Karl Fischer Method Under Flow Injection Analysis Conditions"
Anal. Chim. Acta 2000 Volume 420, Issue 1 Pages 133-142
Nathalie Dantan, Steffen Kr&ouml;ning, Wolfgang Frenzel and Stephan K&uuml;ppers

Abstract: Flow injection procedures for the determination of water in methanol using Karl Fischer method are presented. Both spectrophotometric and potentiometric detection systems were investigated and critically compared with respect to their performance characteristics. A novel tubular differential potentiometric flow through cell has been developed. Using spectrophotometric detection the determination of water at a sampling frequency of about 120 h-1 is possible in the concentration range 0.01-1%. Precision is better than 3% RSD over the entire concentration range. The detectability of the method is severely affected by the presence of water traces in the carrier solvent but with appropriate preventive measures, concentrations as low as 0.002% are accessible. The specifications of the potentiometric variant compare well with the spectrophotometric detection method, yet the former offers slightly better precision but suffers from reduced linear range, Automation of the two methods has been realised and the applicability for on-line monitoring purposes are outlined. Particular emphasis is paid to the calibration problematic. Modified reverse FIA has also been applied and shown to be a simple and reliable way of detecting deviations from nominal values as required in several process control situations.
Water Organic compound Spectrophotometry Potentiometry Karl Fischer analysis

"Capillary Electrochemical Enzyme Immunoassay (CEEI) For Phenobarbital In Serum"
J. Pharm. Biomed. Anal. 1999 Volume 19, Issue 1-2 Pages 145-152
Jin Zhang, William R. Heineman and H. Brian Halsall

Abstract: A competitive heterogeneous capillary enzyme immunoassay with electrochemical detection has been developed for phenobarbital in serum. The oxidized primary antibody was attached covalently to the modified interior surface of a microcapillary (22 µl). The competition between analyte phenobarbital and alkaline phosphatase labeled phenobarbital for a limited number of antibody binding sites was complete in 1.5 h. The enzymatic product (p-aminophenol) from the catalytic conversion of the substrate (p-aminophenyl phosphate) was detected by amperometric flow injection analysis. The calibration curve for phenobarbital had a detection limit of 30 µg L-1 (2.8 pmoles or 0.65 ng) and a range of 30-3000 µg L-1. The assay could be used to determine the phenobarbital serum concentration in a 4 µl clinical serum sample without pretreatment.

"Continuous-flow And Flow Injection PH Gradients For Spectrophotometric Determinations Of Mixtures Of Nucleic Acid Components"
Anal. Chem. 1999 Volume 71, Issue 11 Pages 2215-2220
Javier Saurina, Santiago Hern&aacute;ndez-Cassou, Rom&agrave; Tauler, and Anna Izquierdo-Ridorsa

Abstract: A procedure for the rapid determination of mixtures of nucleic acid components from the anal. of spectrophotometric multivariate data obtained with continuous-flow and flow injection pH-gradient systems is proposed. Three flow systems have been developed and assayed in which an online pH gradient is generated from the mixing and controlled dispersion of acidic and basic titrant solutions Quant. determinations of any particular analyte in the unknown samples in the presence of interferences is performed with a single pure standard for this analyte. They are carried out using an alternating least squares multivariate curve resoln. procedure. The methods proposed have been validated using synthetic and real sample mixtures The results obtained are concordant with the labeled values, and the relative prediction errors are around 5%.

"Calibration In Flame Atomic Absorption Spectrometry Using Time-dependent Concentration Profiles"
Spectrochim. Acta B 2000 Volume 55, Issue 7 Pages 847-852
Ignacio L&oacute;pez-Garc&iacute;a, Pilar Vi&ntilde;as, Jos&eacute; Gonz&aacute;lvez and Manuel Hern&aacute;ndez-C&oacute;rdoba

Abstract: A computer-controlled manifold allowing the automatic collection of concentration profiles for use in flame atomic absorption spectrometry (FAAS) is described. For this purpose a standard solution is pumped at an increasing flow rate, the difference between this flow rate and the nebulizer uptake rate being compensated with water. Next, the sample solution is pumped at a decreasing rate. A 50-s gradient time is used. The absorbance-time profiles thus obtained intersect at a point which permits the concentration to be calculated. The system allows the on-line dilution of solutions which are too concentrated to be measured by direct aspiration. Using a 30 µg mL-1 calcium standard solution for calibration, this analyte can be determined in the 1-200 µg mL-1 range with relative errors below±1%.

"A Knowledge-based System For Real-time Validation Of Calibrations And Measurements"
Chemom. Intell. Lab. Syst. 1999 Volume 46, Issue 1 Pages 57-66
Axel L&ouml;hn and Bernd Hitzmann

Abstract: In this contribution, a knowledge-based system is presented which is able to identify faults during measurements and calibrations of a flow injection analysis (FIA) system. The knowledge-based system is a subtask of the automation system CAFCA, which can be used for the automation of flow systems, and runs on MS-DOS-PCs, Tne knowledge-based system consists of a numerical module as well as a knowledge-based module, where the knowledge about the process analyzer. is implemented using rules, Using these rules faults will be identified fast and reliable. If a fault has been detected, the operator is informed automatically. Furthermore, minor faults can even be corrected by the knowledge-based system. The application of the system shows that it is an efficient support for the operator,

"Calibration By The Gradient Ratio-standard Addition Method In Flow Injection Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 2002 Volume 460, Issue 2 Pages 235-245
Pawe&#322; Ko&#350;cielniak and Joanna Kozak

Abstract: A calibration method has been developed which is realised in the flow injection analysis (FIA) by the gradient technique. According to this method two transient peaks, one for a sample and the other for a sample with standard addition, are recorded and compared point by point in the entire defined time range. The analytical result is estimated on the basis of information gained about the local analyte concentrations in the sample zone. The method allows the results to be reliable when both the non-linear calibration dependence and the interference effect occur. As an example, calcium in synthetic samples containing silicon, phosphate, aluminum, vanadium and titanium, and also in iron ore sample, were determined by flame atomic absorption spectrometry (FAAS). It has been proved, that the method can be effective in overcoming even extremely strong interferences, providing analytical results with average accuracy equal to ~5% and with precision 2-3 times inferior to that obtained by conventional FI calibration. (C) 2002 Elsevier Science B.V. All rights reserved.

"Automated Flow Injection Gradient Technique For Binding Studies Of Micromolecules To Proteins Using Potentiometric Sensors: Application To Bovine Serum Albumin With Anilinonaphthalenesulfonate Probe And Drugs"
Anal. Chem. 1999 Volume 71, Issue 13 Pages 2541-2550
Maria E. Georgiou, Constantinos A. Georgiou, and Michael A. Koupparis

Abstract: An automated flow injection (FI) gradient technique is described for the binding study of the potentiometric probe 1-anilino-8-naphthalenesulfonate (ANS) to bovine serum albumin (BSA). Using a single-channel FI system with a mixing chamber and a flow ANS electrode, the binding parameters (binding constant and number of binding sites) were calculated using the Scatchard model. The concentration. gradient was calibrated by injecting ANS in the stream, and the binding experiment was performed by injecting ANS-BSA solution in the carrier solution of equal albumin concentration. The equations describing the concentration. gradient and the corresponding electrode potential curve are presented. A systematic study of the factors affecting the complexation equilibrium. and the electrode response was performed. For the ANS binding to BSA, two binding classes were determined with binding constants of 2.1 x 10^5 and 3.3 x 10^3 M-1 and 3.8 and 10 binding sites per class, respectively, at 27°C, in 0.10 M phosphate pH 7.4. Competitive binding experiments of sulfamethoxazole, salicylate, azapropazone, ketoprofen, and tolmetin to albumin were also performed by monitoring ANS binding inhibition (decrease of apparent binding constant). This technique takes advantage of FI gradients and direct potentiometry and utilizes the total information contained in FI peaks, providing fast and accurate binding information in a wide range of concentration. ratios.

"Optimization And Empirical Modeling Of HG-ICP-AES Analytical Technique Through Artificial Neural Networks"
J. Chem. Inf. Comput. Sci. 2001 Volume 41, Issue 3 Pages 824-829
Jorge F. Magallanes, Patricia Smichowski, and Julieta Marrero

Abstract: An artificial neural network technique has been applied to the optimization of a hydride generation-inductively coupled plasma-atomic emission spectrometry (HG-ICP-AES) coupling for the determination of cc at trace levels. The back propagation of errors net architecture was used. Experimental parameters and their relationship have been studied, obtaining a surface response of the system. The results and optimization aspects achieved with the neural network approach have been compared to the one variable at time and SIMPLEX methods.

"Synergetic Effects In The Flow Injection Analysis Determination Of Catechol In The Presence Of Excess Ascorbic Acid By Series Dual-band Amperometric Detection"
Anal. Chim. Acta 1999 Volume 385, Issue 1-3 Pages 281-285
Harry B. Mark, Jr., Hong Zhang, Suzanne K. Lunsford, Ozcan Ceylan, Anthony I. Khaskelis, Nada Atta, Ahmed Galal, Sven Hausner, Judith F. Rubinson <i>et al.</i>

Abstract: The deviations at high concentrations (>10^-5 M) in the calibration curves for the determination of catechol in catechol/ ascorbic acid mixtures by flow injection analysis using series dual-band poly(3-methylthiophene)-coated electrodes has been re-examined, The cyclic voltammetry (at pH congruent to 7.4) of catechol/ascorbate and catechol/urate mixtures and NMR measurements show these deviations are the result of the simultaneous homogeneous catalytic reaction of dehydrocatechol with ascorbate.
Catechol Electrode Voltammetry

"Determination Of Lead In Tap Water By ICP-AES With Flow Injection Online Adsorption Preconcentration Using A Knotted Reactor And Ultrasonic Nebulization"
J. Anal. At. Spectrom. 1999 Volume 14, Issue 8 Pages 1239-1243
J. A. Salonia, R. G. Wuilloud, J. A. G&aacute;squez, R. A. Olsina and L. D. Martinez

Abstract: An online lead pre-concentration and determination system implemented with inductively coupled plasma atomic emission spectrometry (ICP-AES) combined with a flow injection (FI) method with ultrasonic nebulization (USN) was studied. The lead was retained as the lead-diethyldithiocarbamate complex at pH 9.5. The lead complex was eluted from the knotted reactor (KR) with 4.0 mol L-1 hydrochloric acid. A total enhancement factor of 140 was obtained with respect to ICP-AES using pneumatic nebulization (14.8 for USN and 9.5 for KR). The detection limit for the pre-concentration of 10 mL of aqueous solution was 0.2 ng mL-1. The precision for ten replicate determinations at the 20 µg L-1 lead level was 2.7% relative standard deviation, calculated with the peak heights obtained. The calibration graph using the pre-concentration system for lead was linear with a correlation coefficient of 0.9993 at levels near the detection limits up to at least 100 ng mL-1. The method was successfully applied to the determination of lead in tap water samples.

"Exploiting Monosegmented Flow Analysis To Perform In-line Standard Additions Using A Single Stock Standard Solution In Spectrophotornetric Sequential Injection Procedures"
Anal. Chim. Acta 2002 Volume 466, Issue 2 Pages 345-352
Marcelo S. Pinto Silva and Jorge C. Masini

Abstract: The robustness of sequential injection analysis (SIA) was combined with the monosegmented flow analysis (MSFA) approach, in which there is no dispersion of the reaction zone with carrier, to develop a methodology to perform in-line dilution. This approach allows one to know accurately the dilution of sample and reagent inside the monosegment, without the need for determination of dispersion coefficients. As a consequence, the methodology allowed the mechanization of procedures to perform standard additions and to construct analytical curves using a single stock standard solution, with very simple and conventional computation of the sample concentration. The method was illustrated with experiments using the bromothymol blue (BTB) dye, in which no reactions are involved, as well as with the spectrophotometric methodology for determination of Fe(II) using o-1,10-phenanthroline as chromogenic reagent. The resulting method presented a sampling frequency of 30 analyzes per hour and a detection limit of 25 µg 1-1. (C) 2002 Elsevier Science B.V. All rights reserved.

"Binding Assays In Heterogeneous Media Using A Flow Injection System With An Expanded Micro-bed Adsorption Column"
Bioseparation 1999 Volume 8, Issue 1-5 Pages 237-45
Bo Mattiasson, M. P. Nandakumar

Abstract: Competitive binding assays have been performed in flow injection systems. To further increase the versatility of the system, and to enable it to deal with samples containing particulate matter, the adsorption step was designed as an expanded bed column. Immunochemical quantification of human serum albumin was chosen as a model system to use for the development of the technology. A competitive ELISA was set up using peroxidase labelled HSA as competing ligand. The introduction of the expanded bed immunosorption column made the system tolerant to samples containing suspended particulate matter. The analytical outcome is very similar to that from the packed bed system even though more time is required for each assay cycle. The capability of the system was tested by addition of increasing amounts of yeast cells. The results clearly indicate that the system is suitable e.g. for process monitoring of fermentations.

"Flow Injection Analysis Of Intracellular β-galactosidase In Escherichia Coli Cultivations, Using An Online System Including Cell Disruption, Debris Separation And Immunochemical Quantification"
Bioseparation 1999 Volume 8, Issue 1-5 Pages 255-267
Anita Tocaj, M.P. Nandakumar, O. Holst, B. Mattiasson

Abstract: A continuous integrated process for online quantification of intracellular components has been developed. By applying the concept of expanded micro-beds in a flow injection system it was possible to first perform online cell disintegration followed by an online binding assay for quantification of a reporter protein (β-galactosidase) from the cell interior. The disintegration process involved the use of an expanded bed with immobilized lysozyme followed by ultrasonic treatment in a flow-through cell. The cell debris does not interfere in the binding assay as it is carried out in an expanded bed. The time for an assay cycle is at present approximately 35 min. This integrated system can be used for quantification of proteins down to at least 10^-7 mol/L.

"Membrane-controlled Reagent-delivery Systems - A New Approach For The Continuous Production Of Reagent And Standard Solutions"
Fresenius J. Anal. Chem. 2001 Volume 370, Issue 7 Pages 893-898
H. Albus, B. Neidhart

Abstract: A new simple and robust system for the production of standard solutions, based on the mass-transfer of analytes through membranes, is described. The device consists of a cone-shaped reservoir vessel, filled with a concentrated solution of the analyte and separated from a liquid acceptor stream by a membrane. Mass-flow from donor to acceptor solution is controlled by the mass-transfer-affecting properties of the active membrane area, which is determined by the hole in a template (diameter 0.8 mm) placed between the membrane and the acceptor-channel. Using nitrate as model analyte and a track-etched membrane filter (pore size 0.1 mum) dilution factors up to 2,400,000 with long-term reproducible accuracy of < 2% have been achieved. Adjustment of a requested concentration is possible by varying either the flow rate of the acceptor stream or the concentration of the reservoir solution.

"Multivariate Standardization Techniques On Ion-selective Sensor Arrays"
Analyst 1999 Volume 124, Issue 7 Pages 1045-1051
F. Sales, M. P. Callao and F. X. Rius

Abstract: Multivariate standardization techniques [slope/bias (S/B) correction, single wavelength standardization (SWS) and piecewise direct standardization (PDS)] were used to attempt to correct changes over time in multivariate calibration models for potassium and calcium. These models were constructed with ion-selective electrode (ISE) arrays. Multivariate PDS local models which included the correlation between the sensors of the array were better than the other simple techniques. We considered the relationship between the variables (sensors) and, in the PDS treatment, we have indicated their arrangement which is taken from the loadings plot. We used the Kennard-Stone algorithm to select the standardization samples from the original responses of the samples and the partial least squares (PLS) scores of each model. These scores include information about the concentrations. The models and standardizations were validated by predictions on real samples such as natural waters. The best standardization conditions provided unbiased predictions with no loss of precision.

"Analysis Of K(I) And Ca(II) In Natural Waters By Means Of An Array Of Alkali And Alkaline Earth Ion-selective Electrodes"
Quim. Anal. 1999 Volume 18, Issue 3 Pages 247-253
F. Sales, M.P. Callao and F.X. Rius

Abstract: A methodology has been set up for the simultaneous determination of K(I) and Ca(II) in natural waters. It uses an array of seven ion-selective electrodes which respond to alkali and alkaline earth ions. A comparative study was made of the results obtained by multivariate partial least squares (PLS) and univariate calibration models. The results of analyzing real samples and determining the concentration of both analytes with the two techniques used indicate that univariate calibrations give systematic error because of the effect of interference, whereas multivariate calibrations can provide results that are error free and more reproducible. For some samples with low concentrations, both calibrations gave similar results because the contributions of secondary electrodes to the prediction were not big enough to compensate for the interference.

"Flow Injection Fluorimetric Determination Of 1,4-benzodiazepines In Pharmaceutical Formulations After Acid Hydrolysis"
J. Pharm. Biomed. Anal. 1999 Volume 20, Issue 1-2 Pages 357-362
J. Dolej&#353;ov&aacute;, P. Solich, Ch. K. Polydorou, M. A. Koupparis and C. E. Efstathiou

Abstract: A simple, rapid and fully automated flow injection method with fluorimetric detection after hydrolysis with H2SO4 in ethanolic or methanolic medium at room temperature has been developed for the determination of 1,4-benzodiazepines (oxazepam, diazepam and nitrazepam) in pharmaceutical formulations. The calibration curves are linear in the ranges (mg ml-1) of oxazepam (0.025-0.150), diazepam (0.010-0.125) and nitrazepam (0.010-0.150), with detection limits of 0.01, 0.005 and 0.005 mg mL-1, respectively, and RSD (1% (n = 10). The measurement throughput is 60 h-1 using a 200 µl sample volume obtained by the direct dissolution of formulations in alcohol.

"Continuous-flow Analysis Of Dissolved Inorganic Carbon Content In Seawater"
Anal. Chem. 2001 Volume 73, Issue 17 Pages 4111-4116
M. H. C. Stoll, K. Bakker, G. H. Nobbe, and R. R. Haese

Abstract: A rapid, continuous-flow determination of total inorganic carbon (TIC) in seawater samples is presented. The method runs on an autoanalyzer Traacs 800 spectrophotometric system and is calibrated versus certified reference materials readily available. Atypical analysis speed of 45 samples/h can be reached with an accuracy of 2-3 muM and a precision of similar to2.5 muM. The analysis requires only a small amount of sample and is thus ideally suited for pore water samples and samples taken from cultures where sample volume is at a premium. The speed of the analysis makes mapping of oceanic surface water characteristics possible. Potential interference of sulfide in anoxic (e.g., pore water) samples can be masked by the addition of a hydrogen peroxide step. Although the latter is a strong oxidative reagent, no significant effect on TIC concentration due to oxidation of (labile) organic matter could be found.

"Soil Analysis Procedures Using 0.01 M Calcium Chloride As Extraction Reagent"
Commun. Soil Sci. Plant Anal. 2000 Volume 31, Issue 9-10 Pages 1299-1396
Houba, V.J.G.;Temminghoff, E.J.M.;Gaikhorst, G.A.;Van Vark, W.

Abstract: This publication gives details of laboratory procedures for the determinations of bioavailable (e.g., plants) quantities of nutritional and polluting inorganic elements in 0.01 MCaCl2 extracts of air-dry soil samples. Air-day soil samples are extracted for two hours with a 0.01 M CaCl2 solution of 20°C in a I:10 extraction ratio (W/V). After measuring the pH in the settling suspension, the concentrations of nutritional and polluting elements are measured in the clear centrifugate or filtrate. The procedure is simple, easy to perform, and cheap (labor, chemicals) in daily use in routine soil laboratories. The method receives internationally more and more attention as an alternative for the many extraction procedures for a single nutrient or pollutant that are still in use nowadays. The soil is extracted with a solution what has more or less the same ionic strength as the average salt concentration in many soil solutions. Various nutrients and metals can be measured in a single extract that allows considering relationships between them during interpretation of the data. For most elements, different detection techniques are described in detail in this publication. Detailed laboratory procedures are described for the determination of pH, total dissolved organic carbon, nitrate, ammonium, total dissolved nitrogen, sulfate, total dissolved sulfur, ortho-phosphate, total dissolved phosphate, sodium, potassium, magnesium, cadmium, copper, nickel, lead, aluminum, iron, arsenic, boron, and phenols. Since only one extract of soil samples is used, profitable use can be made of multi-element detection techniques like segmented-flow analysis spectrometry, ICP-OES, and ICP-MS.

"Flow Injection Determination Of Phenols With Tyrosinase Amperometric Biosensor And Data Processing By Neural Network"
Chem. Anal. 1999 Volume 44, Issue 5 Pages 865-878
M. Trojanowicz, A. Jagielska, P. Rotkiewicz and A. Kierzek

Abstract: A multi-membrane amperometric biosensor prepared with immobilized tyrosinase on a platinum disk electrode in a large-volume wall-jet flow-through cell was applied for the determination of phenolic compounds via flow injection measurements. For data processing of measurements carried out simultaneously with several biosensors of different selectivity using different membranes in three-component mixtures of phenol, catechol and m-cresol, a three layer artificial neural network with feedforward connections, sigmoidal transfer function and back propagation learning algorithm was employed. The best functional parameters of the network were found to be 5 inputs, 3 neurons in the hidden layer and 10000 learning cycles. For 36 samples analyzed the best correlation coefficient values were obtained for catechol (0.96) and phenol (0.88). Results for m-cresol, which produced the smallest: amperometric signal with all biosensors tested were only semi-quantitative (correlation coefficient 0.67).

"Selective Reduction Method For Separate Determination Of Inorganic And Total Mercury In Mussel Tissue By Flow Injectioncold Vapor Technique"
Ecotoxicol. Environ. Saf. 1999 Volume 42, Issue 3 Pages 245-252
S. R&iacute;o-Segade and C. Bendicho

Abstract: A flow injection cold vapor atomic absorption spectrometry (FI-CV-AAS) method was developed to determine inorganic mercury and total mercury in mussel samples obtained from the Galicia coasts. The mussel samples were digested in a microwave oven using an HNO3/H2O2 mixture and then total mercury was determined using sodium borohydride as reducing agent. In a separate subsample, following ultrasonic extraction in hydrochloric acid medium, inorganic mercury was determined by selective reduction using stannous chloride in acid medium as reducing agent. The accuracy of the digestion method was checked by analyzing BCR Reference Material No. 278 Mussel Tissue (Mytilus edulis). There were no significant differences between the certified and found concentration values. As a certified reference material of mussel tissue containing both methylmercury and inorganic mercury was not available, recovery studies on mussel tissue samples spiked with inorganic mercury and methylmercury were done to check the reliability of the method. The results revealed that the mercury contained in mussel samples was methylmercury. Copyright 1999 Academic Press.

"Gradient Techniques In Flow Injection Analysis. Stopped-flow Measurement Of The Activity Of Lactate Dehydrogenase With Electronic Dilution"
Anal. Chim. Acta 1982 Volume 136, Issue 1-2 Pages 101-112
S. Olsen, J. Rika and E. H. Hansen

Abstract: The feasibility of selecting reproducibly a suitable element of the dispersed sample zone in a flow injection system is exploited for stopped-flow measurement of the enzymatic activity of lactate dehydrogenase. By electronic selection of different segments along the gradient and monitoring of the stopped-flow intervals with a computer, this technique can be extended to cover wide concentration ranges while maintaining the inherent high precision of flow injection measurements. This approach is further pursued by designing a general technique for electronic dilution and electronic calibration by which a multipoint calibration curve may be constructed using a single injection of sample material.
Enzyme, lactate dehydrogenase Spectrophotometry

"Flow Injection Calibration Methods For Atomic Absorption Spectrometry"
Anal. Chim. Acta 1983 Volume 145, Issue 1 Pages 159-168
J. F. Tyson, J. M. H. Appleton and A. B. Idris

Abstract: The use of an atomic absorption spectrometer as a detector in flow injection analysis is briefly reviewed. A new simplified model is described for the dispersion effects observed with such systems; the model is based on considering the dispersion to be due to a single hypothetical mixing chamber located immediately prior to the measurement stage. The utility of this approach is demonstrated for two methods of calibration commonly used in atomic absorption spectrometry, and it is shown that flow injection sample and standard handling techniques are comparable to manipulation with volumetric apparatus. The flow injection method has a number of advantages for the analogue of the standard addition method. The use of an exponential concentration gradient is proposed as a novel method of calibration using a single concentrated standard. Results are presented for the determination of chromium in standard steels.
Chromium Alloy Spectrophotometry

"A Kalman Filter For Calibration, Evaluation Of Unknown Samples And Quality Control In Drifting Systems. 1. Theory And Simulations"
Anal. Chim. Acta 1984 Volume 156, Issue 1 Pages 87-101
P. C. Thijssen, S. M. Wolfrum and G. Kateman, H. C. Smit

Abstract: In the method described for online 'drift' compensation, the two 'drifting' parameters that describe a rectilinear calibration graph are processed by a Kalman filter algorithm. For the evaluation of unknown samples, the parameters predicted by the recursive algorithm are used. The procedure also incorporates a quality-control stage, by means of which it can be decided after each measurement whether or not re-calibration is necessary. Application of the technique is demonstrated for data from a flow injection determination of Cu with EDTA.
Copper Spectrophotometry

"A Kalman Filter For Calibration, Evaluation Of Unknown Samples And Quality Control In Drifting Systems. 4. Flow Injection Analysis"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 27-40
P. C. Thijssen, L. T. M. Prop and G. Kateman, H. C. Smit

Abstract: The application of state estimation in flow injection analysis is described. This method allows the online correction of drift on the calibration graph. The entire calibration system, which is tabulated and summarized, furnishes a set of algorithms for prediction, filtering, evaluation, control, optimization and smoothing. The selection and verification of the calibration model and noise co-variances used were investigated. To demonstrate the applicability of the calculations, an automated flow injection system was used to determine Cl- in aqueous samples, based on the metathesis of SCN- in Hg(SCN)2 by Cl- in the presence of Fe(III) , with measurement of the complex at 470 nm.
Chloride Water Spectrophotometry

"Microcomputer-based Peak-width Method Of Extended Calibration For Flow Injection Atomic Absorption Spectrometry"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 481-486
Stephen R. Bysouth and Julian F. Tyson

Abstract: Peak-width calibration deviates from a straight line as peaks are broader than expected at higher concentration. For Cr, Mg and Ni in the ranges 40 to 1000, 1 to 50 and 20 to 1000 mg l-1, respectively, the coefficient of variation are between 2.18 and 12.8% (n = 10 at each of three levels in the ranges). The method is limited by the reproducibility of the absorbance - time profile and the rate of data acquisition. Use of a cubic function, with least-squares fitting, is proposed, and this can be applied to calculate dilution factors to enable further measurements to be made within the concentration. range of max. accuracy.
Chromium Magnesium Nickel Spectrophotometry

"Sandwich Techniques In Flow Injection Analysis. 1. Continuous Recalibration Techniques For Process Control"
Anal. Chim. Acta 1987 Volume 199, Issue 1 Pages 191-196
J. Alonso, J. Bartrol&iacute;, M. Del Valle, M. Escalada and R. Barber

Abstract: The technique of sample insertion between two different standard solution used as carrier streams is described. The proposed re-calibration technique enables the construction of simple, reliable and cheap automatic monitors for process control; relatively frequent re-calibration is required for quantitative measurements. Spectrophotometric and ion-selective electrode monitoring procedures are outlined.
Electrode Potentiometry Spectrophotometry

"Multicomponent Determinations In Flow Systems By Partial Least Squares Modeling"
Anal. Chim. Acta 1988 Volume 211, Issue 1-2 Pages 1-10
Ingrid Lukkari, Walter Lindberg

Abstract: Multivariate calibration was used for data analysis in continuous-flow and flow injection systems. Titrations of UV-absorbing organic acids were studied for experimental evaluation of the concepts involved, with single- or multi-wavelength detection and diode-array detection. Experimental arrangements for achieving a concentration. gradient of the sample in the reagent stream are discussed. Multi-component determinations were made, based on the peak shape of the signal.
Acids, organic Spectrophotometry Spectrophotometry

"Automated Spectrophotometric Field Monitor For Water Quality Parameters. Determination Of Ammonia"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 401-407
J. Richard Clinch and Paul J. Worsfold, Frank W. Sweeting

Abstract: A manual flow injection manifold (illustrated) was incorporated into an automated field monitor as described previously (Anal. Abstr., 1988, 50, 6H74). Sample (0.7 mL min-1) and NaOH (0.7 mL min-1) were mixed online in a 50-cm reaction coil before introduction into the water carrier stream (0.7 mL min-1). The carrier stream then passed together with bromothymol blue solution into a gas diffusion cell and the acceptor stream flowed to a solid-state spectrophotometric detector for determination of total NH3 at 635 nm. The calibration graph was rectilinear obtained for up to 5000 µg L-1 of NH3 and the limit of detection was 17 µg l-1. The coefficient of variation (n = 6) were 0.7 to 2.1%. Results are presented for a three-day field trial.
Ammonia Environmental Spectrophotometry

"Online Electrolytic Dissolution Of Alloys In Flow Injection Analysis. 2. Spectrophotometric Determination Of Molybdenum In Steels"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 397-400
H. Bergamin F&deg;, F. J. Krug, B. F. Reis, J. A. Nobrega, M. Mesquita and I. G. Souza

Abstract: A solid sample was placed on a simple electrolytic chamber and 200 mA DC was applied for 8 s; the dissolved material served as the injected sample zone. The carrier electrolyte solution was 1 M KCl - 0.1 M HCl, the reducing reagent solution was 5% SnCl2.2H2O in 5 M HCl and the reagent solution was aqueous 6% KSCN (flow rates 3.7, 1.0 and 1.0 mL min-1, respectively). The optimum length of the main reaction coil was 150 cm and an 8-cm sampling loop was used. The Mo was determined spectrophotometrically. No measurable baseline drift was observed during continuous operation for 4 h. The calibration graph was rectilinear for up to 600 mg L-1 of Mo; the coefficient of variation (n = 10) for a standard sample containing 2.21% of Mo was 2.3%. (For Part I see Anal. Abstr., 1987, 49, 8B210).
Molybdenum Alloy Spectrophotometry

"Novel Use Of Doublet Peaks In Flow Injection Analysis. Simultaneous Spectrophotometric Determination Of Nickel(II) And Iron(II)"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 197-205
David A. Whitman, Gary D. Christian and Jaromir Ruzicka

Abstract: For the determination of Ni (0.17 to 0.24M) and Fe(II) (2.7 to 5.4 mM) in the same solution, e.g., electroplating bath solution, a flow injection system was used in which the absorbance was measured at 395 nm of Ni(II) and of Fe as Fe(III) after reaction in a 25-cm knotted coil with freshly (online) mixed 2% KSCN and 1% K2S2O8, which served as both reagent and carrier stream (1.5 mL min-1). Two different detector cell configurations were used (descriptions given) according to required sample size (20 to 200 or 200 to 500 µL). Individual elements could be monitored by much weaker peaks at 675 nm (Ni) and 505 nm (Fe(II)). Rectilinear calibration graphs were obtained within the cited ranges, and the general utility of the doublet-peak technique was assessed.
Iron(2+) Nickel(II) Industrial Spectrophotometry

"Spectrophotometric Determination Of Trace Uranium In Geological Samples By Flow Injection Analysis With Online Levextrel Resin Separation And Preconcentration"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 279-288
Xing Wu and Weiyi Qi

Abstract: Geological materials (0.1 to 0.2 g) were dissolved in mixed acids, the acid was evaporated and the moist residue was dissolved in 1 mL of 7 M HNO3. The solution was mixed with 100 mg of masking agents [NaF - H3BO3 - EDTA (2:8:5)] and diluted to 10 mL with water and the supernatant solution was aspirated in the flow injection system (illustrated). The U was selectively adsorbed on a micro-column (4 cm x 4.4 mm) of Levextrel CL-5209 resin (120 to 200 mesh) and subsequently eluted with aqueous 0.5% NaF - 0.4% diethylenetriaminepenta-acetic acid. The eluate was then mixed with aqueous dye solution (arsenazo III - chloroacetic acid - H3BO3) and the absorbance of the solution was measured at 649 nm. The calibration graph was rectilinear for up to 0.3 mg L-1 of U and the detection limit was 3 µg l-1. The coefficient of variation (n = 11) for 0.03 and 0.18 mg L-1 of U were 4.72 and 0.57%, respectively. Results for eight geological standards agreed with certified values.
Uranium Geological Spectrophotometry

"Enzymatic Methods For The Determination Of Ethanol Based On Linear And Cyclic Flow Injection Systems"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 161-172
A. M. Almuaibed and Alan Townshend

Abstract: Mini-columns (2.5 cm x 2.5 mm) containing(I) alcohol dehydrogenase bonded to controlled-pore glass and(II) aldehyde dehydrogenase bonded to CNBr-activated Sepharose 4B were used in a linear or a closed-loop flow injection system for ethanol oxidation with formation and fluorimetric detection of NADH at 460 nm (excitation at 360 nm) or spectrophotometric detection at 340 nm. In the linear system the carrier stream contained 1.8 mM NAD+, 0.15 M KCl, 1 mM 2-mercaptoethanol and 0.05 M Na4P2O7 adjusted to pH 9.0 with 0.1 M NaOH. The cyclic system also contained a column (5 cm x 2.5 mm) of glutamate dehydrogenase for regeneration of NAD+, and the carrier stream (adjusted to pH 8.5 instead of 9.0) contained additionally 0.02 M NH4Cl and 0.01 M 2-oxoglutarate. The linear system provided the more sensitive conditions, with a rectilinear calibration range of 0.17 to 4 mM ethanol.
Ethanol Fluorescence Spectrophotometry

"Rapid Spectrophotometric Determination Of Total Phosphorus In Industrial Wastewaters By Flow Injection Analysis Including A Capillary Digestor"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 229-237
M. Aoyagi, Y. Yasumasa and A. Nishida

Abstract: Sample solution in water (as carrier) merged with oxidizing agent (K2S2O8 in H2O) before passing to a digestion unit consisting of 10 m of PTFE tubing holding 10 m of platinum wire (0.2 mm diameter) wound round an aluminum bobbin and heated to 160°C. The solution then mixed sequentially with reducing agent (aqueous 5% Na2S2O3) and color-forming reagent [aqueous malachite green (C. I. Basic Green 4) and (NH4)6Mo7O24.4H2O in ~15% H2SO4] and the absorbance was measured at 650 nm. Calibration graphs were rectilinear for up to 500 ng mL-1 of P and the determination limit was 2 ng mL-1. The coefficient of variation (n = 5) at 200 and 2 ng mL-1 were 0.3 and 6.0%, respectively. Recoveries were quantitative. The method was applied to determine P in industrial waste water and seawater; results agreed with those from the standard procedure.
Phosphorus Sea Waste Water Spectrophotometry Sample preparation

"Lead Preconcentration With Flow Injection For Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 329-337
S. R. Bysouth and J. F. Tyson, P. B. Stockwell

Abstract: Three flow injection manifolds were evaluated for the cited determination. The manifolds each involved a column containing, e.g., quinolin-8-ol material, an autosampler and an AAS detector. Elution was with HCl. Timed sample loading and matrix removal without passing the matrix to the nebulizer were achieved with one valve, but reagent consumption and calibration time were reduced by incorporating further valves. The effects of pH and interfering ions were studied. Water samples from lead pipes were analyzed by using a 2-valve manifold, a column packed with 2-methylquinolin-8-ol and direct neblization. Detection limits down to 1.4 ng mL-1 were achieved.
Lead Water Spectrophotometry

"Flow Injection System With Ion-exchange Separation And Potentiometric Detection For The Determination Of Three Halides"
Anal. Chim. Acta 1989 Volume 219, Issue 1 Pages 55-65
Jacobus F. van Staden

Abstract: Halides were separated on a column (8 cm x 2.8 mm) of Dowex 1-XB (NO3 - form; 100 to 200 mesh) incorporated in a flow injection system fitted with a tubular Ag - silver halide ion-selective electrode as potentiometric sensor. Injected samples (30 µL) were mixed in a coil (105 cm x 0.51 mm) with the carrier stream (0.1 M KNO3) at a flow rate of 3.9 mL min-1. Chloride, Br- and I- were eluted in that order from the anion-exchange column. Then, 0.5 M KNO3 was added to the eluate at a flow rate of 1.4 mL min-1 , and after further mixing in a coil (1.6 m x 0.51 mm), the potential was measured. Calibration graphs were rectilinear from 20 to 5000 mg L-1 for single and mixed halide solution The detection limit was 5 µg l-1.
Chloride Bromide Iodide Potentiometry Electrode

"Determination Of Trace Water In Non-polar Organic Solvents With A Flow Injection System And Tin Tetrachloride Or Antimony Pentachloride"
Anal. Chim. Acta 1989 Volume 220, Issue 1 Pages 55-63
Jae-Seong Rhee and Purnendo K. Dasgupta, Don C. Olson

Abstract: The flow injection system was constructed from PTFE tubing (0.6 to 0.8 mm i.d.). In operation, solution of SnCl4 or SbCl5 in anhydrous benzene (I) were merged with a I, hexane (II) or 1,2-dichloroethane (III) carrier stream (0.34 mL min-1) into which the sample of I, II or III, respectively, was injected. Hydrolysis of the halide in a knotted mixing line (30 cm x 0.6 mm plus 10 cm x 0.8 mm) was monitored at 305, 300 or 295 nm for SnCl4, or from 350 to 420 nm for SbCl5. Detection limits ranged from 2 to 5 mg kg-1. A membrane-permeation-based calibration method for preparing trace water standards is also described. The throughput was 70 h-1.
Water Organic compound Spectrophotometry

"Flow Injection Determination Of Malate With Immobilized Malate Dehydrogenase"
Anal. Chim. Acta 1989 Volume 221, Issue 2 Pages 337-340
Ala'ddin M. Almuaibed and Alan Townshend

Abstract: Malate dehydrogenase was immobilized on controlled-pore glass and packed in a glass column (2.5 cm x 2.5 mm); the column was used in a flow injection system. The carrier stream (2 mL min-1) consisted of 0.1 M phosphate buffer (pH 11.5) - 3.6 mM NAD+ (1:1); detection was at 340 nm. The detection limit was 7 µM and calibration graphs were rectilinear for 0.9 mM malate. The coefficient of variation (n = 10) was 1.5% for 0.44 mM. The column was stable for 1 month without loss in activity. The sampling rate was 50 h-1. Malate dehydrogenase was immobilized on controlled-pore glass and packed in a glass column (2.5 cm x 2.5 mm); the column was used in a flow injection system. The carrier stream (2 mL min-1) consisted of 0.1 M phosphate buffer (pH 11.5) - 3.6 mM NAD+ (1:1); detection was at 340 nm. The detection limit was 7 µM and calibration graphs were rectilinear for 0.9 mM malate. The coefficient of variation (n = 10) was 1.5% for 0.44 mM. The column was stable for 1 month without loss in activity. The sampling rate was 50 h-1.
l-Malate

"Simultaneous Spectrophotometric Determination Of Lanthanum And Calcium With An Automated Flow Injection Analyser"
Anal. Chim. Acta 1989 Volume 222, Issue 1 Pages 205-209
Danhua Chen, Ruxiu Cai and Yun'e Zeng

Abstract: Lanthanum and total lanthanum plus calcium were determined by flow injection analysis (apparatus described and illustrated) with use of 2-(2-arsenophenylazo)-7-(2,4,6-trichlorophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid and 7-(4-fluoriphenylazo)-2-(2-phosphono-4-chlorophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonate, respectively; Ca was determined by calculation. Calibration graphs were rectilinear for 0.2 to 1.6 µg mL-1 of Ca and La. The injection rate was 90 h-1, and coefficient of variation were generally 5% (n = 5). Magnesium, Cu(II), Fe(II) and Mn(II) interfered significantly with the determination of calcium. Interference from Fe(III) in the determination of La could be eliminated by addition of 1% ascorbic acid solution
Lanthanum Calcium Spectrophotometry

"Flow Injection Extraction-spectrophotometric Determination Of Dichromate With The Tetramethylenebis(triphenylphosphonium) Cation"
Anal. Chim. Acta 1989 Volume 225, Issue 1 Pages 241-246
D. Thorburn Burns, N. Chimpalee and M. Harriott

Abstract: Samples (0.25 ml) were injected into a stream (0.85 mL min-1) of water which was mixed with a stream (0.85 mL min-1) of 1 M H2SO4. This mixture was merged with a stream (0.85 mL min-1) of aqueous 0.5% tetramethylenebis(triphenylphosphonium) bromide in a PTFE reaction coil (20 cm x 0.8 mm), and the resulting ion pair was extracted into CHCl3 in a second PTFE coil (0.4 m x 0.8 mm). The mixture was passed through a phase separator, and the absorbance of the organic phase was measured at 365 nm. The calibration graph was rectilinear for 20 µg mL-1 of Cr2O72-, and the detection limit was 0.44 µg mL-1. The method was applied in the determination of Cr2O72- in steel.
Dichromate Alloy Spectrophotometry Sample preparation

"High Reliability And Stability Of Enzyme Cartridges In Flow Injection Analysis"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 253-262
T. Dullau, B. Reinhardt and K. Sch&uuml;gerl

Abstract: A flow injection system consisting of a membrane pump, a sampling valve, two or more enzyme cartridges and an amperometric oxygen electrode detector was used to determine glucose, lactate and maltose in fermentation broths during cell cultivation and product formation. Selectivity was achieved by immobilizing glucose oxidase, lactate oxidase and α-glucosidase on polymeric carrier materials. Calibration graphs for glucose and lactate were rectilinear up to 6 and 8 g l-1, respectively. The cartridges were easily prepared, reliable and stable for 6 months. Concentrations of different substrates could be measured in a single analysis by switching from one cartridge to another. The system could be used for online measurement and control of biotechnological production processes.
Glucose Lactose Maltose Fermentation broth Sensor Amperometry Electrode

"Determination Of Low Concentrations Of Chlorite And Chlorate Ions By Using A Flow Injection System"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 437-441
Demetrius G. Themelis, Delmer W. Wood and Gilbert Gordon

Abstract: Determination of ClO2- alone and in mixtures with ClO3- was achieved by reaction with I- at pH 2 to liberate I, which was measured spectrophotometrically at 370 nm. Both ClO2- and ClO3- react with I- in 6 M HCl, and the individual species were determined by multiple regression. The calibration graph was rectilinear from 2 to 150 µM-ClO2- and from 2 to 100 µM-ClO3-, with coefficient of variation of 0.4 and 1.2%, respectively. Detection limits were 0.04 mg L-1 for ClO2- and 0.03 mg L-1 for ClO3-. The method was fast and simple and suitable for sub mg L-1 levels in drinking water. Determination of ClO2- alone and in mixtures with ClO3- was achieved by reaction with I- at pH 2 to liberate I, which was measured spectrophotometrically at 370 nm. Both ClO2- and ClO3- react with I- in 6 M HCl, and the individual species were determined by multiple regression. The calibration graph was rectilinear from 2 to 150 µM-ClO2- and from 2 to 100 µM-ClO3-, with coefficient of variation of 0.4 and 1.2%, respectively. Detection limits were 0.04 mg L-1 for ClO2- and 0.03 mg L-1 for ClO3-. The method was fast and simple and suitable for sub mg L-1 levels in drinking water.
Chlorite Chlorate ion Water Spectrophotometry

"Radiometric And Fluorimetric Determination Of Aminosilanes And Protein Covalently Bound To Thermally Pre-treated Glass Substrates"
Anal. Chim. Acta 1990 Volume 228, Issue 1 Pages 107-116
Laurie Locascio-Brown, Anne L. Plant and Richard A. Durst, Marius V. Brizgys

Abstract: Derivatization of soda-lime glass spheres with aminosilanes and the stability of these groups at near-physiological pH in flow streams of aqueous buffered solution were studied. The extent of silanization was determined by a radioactive tracer method and a method based on a fluorescent marker, which confirmed the presence of immobilized and adsorbed amines in the nmol range. A method for covalently attaching bovine serum albumin to the beads via a cross-linking reagent which reacts selectively with amines is described. Thermal pre-treatment of the glass before derivatization enhanced suface derivatization with aminosilanes. Less than monolayer films prepared with monofunctional silanes were stable, after initial conditioning, with a 3% loss over 24 h in constantly flowing solution at pH 8, allowing the design of reusable immunoassay systems which were readily calibrated.
Protein Aminosilanes Immunoassay Radiochemical Fluorescence

"Flow Injection Determination Of Mixtures Of Amines Immobilized In The Flow Cell Of A Photometric Diode-array Detector"
Anal. Chim. Acta 1990 Volume 229, Issue 1 Pages 177-182
Beatriz Fernandez-Band, Fernando L&aacute;zaro, M. D. Luque de Castro and Miguel Valcarcel

Abstract: Mixtures of 2,4-dinitrophenylhydrazine (I) and 2- and 4-nitrophenylhydrazine in 0.1 M phosphate buffer (pH 6.5) containing 5% of methanol were injected into the manifold of a single-channel flow system and passed, in a carrier stream (1.1 mL min-1) of 0.1 M phosphate buffer (pH 6.5) - methanol (3:2), through the detector flow cell packed with C18 bonded silica. The amines were concentrated, retained and determined in situ. Spectra were recorded from 300 to 500 nm, and three wavelengths per analyte were selected for calibration and separation of the mixtures. The retained compounds were rapidly eluted by the carrier, allowing a sampling frequency of 40 h-1. Calibration graphs were rectilinear from 0.5 (determination limit) to 10 µM for each amine, and the coefficient of variation (n = 11) at 20 µM-I was 1.4%.
Amines

"Integrated Reaction And Photometric Detection With Enzymes Immobilized In The Flow Cell Of A Flow Injection System"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 199-202
Pilar Linares, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Alcohol dehydrogenase was immobilized on the walls of the detector cell by use of controlled-pore glass as support (cf. Masoom and Townshend, Ibid., 1986, 179, 399). Simultaneous dual-valve injections were made of sample and NAD+ into separate streams of 0.8% semicarbazide hydrochloride solution in 0.075 M K4P2O7 buffer (pH 7.5), and the merged streams passed through a delay coil (35 to 65 s) before stopped-flow absorbance measurement at 340 nm. Regression parameters are tabulated for various combinations of optical pathlength (0.5 to 5 mm) and stop-time (1 to 5 s). The calibration graph was rectilinear typically for 2 to 500 µg mL-1 of ethanol.

"Simultaneous Flow Injection Determination Of Aluminum And Zinc Using LED Photometric Detection"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 125-130
Marek Trojanowicz and Joanna Szpunar-obiska

Abstract: The sample solution was injected into a carrier stream of 0.4 M acetate buffer (pH 4.5) that was then blended with aqueous 0.05% xylenol orange and passed through a reaction coil before detection in a 1.5-cm path-length flow cell by sequential operation of light-emitting diodes with emission max. at 563, 580 and 638 nm under computer control so that separate peak heights for the two analytes could be obtained by multiple linear regression with matrix inversion. Rectilinear calibration graphs were obtained for 0.2 to 25 µg mL-1 of Al and 0.2 to 30 µg mL-1 of Zn, and each could be determined in the presence of a 100-fold concentration. of the other. Several metals and anions interfered; interference from Fe(III) was minimized by reduction with ascorbic acid and masking with EDTA. The method was applied to alloys.
Aluminum Zinc Alloy Spectrophotometry

"Flow Injection Extraction-spectrophotometric Method For The Determination Of Lead And Its Combination With Minicolumn Preconcentration"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 157-162
E. A. Novikov, L. K. Shpigun and Yu. A. Zolotov

Abstract: Two flow injection systems were devised, one without and one with ion-exchange pre-concentration. [2-mm-i.d. glass column of Chelex-100 resin (NH4+ form; 50 to 100 mesh)]. The Pb(II) was extracted from an aqueous HNO3 carrier stream into dicyclohexano-18-crown-6 solution in CHCl3 in a PTFE coil (2 m x 0.5 mm), and after phase separation in a membrane separator the CHCl3 layer was treated with 0.002% dithizone - 0.4% triethanolamine solution in CHCl3 (mixing ratio 3:2) in a 30-cm PTFE reaction coil for absorbance measurement at 512 nm. With ion-exchange pre-concentration. for 79 s, the calibration graph was rectilinear in the range 10 to 200 µg l-1, the detection limit was 5 µg L-1 and the coefficient of variation at 100 µg L-1 was 9% (n = 4). Test applications to analyzes of alloys, soil extracts and seawater are described briefly.
Lead Sea Environmental Alloy Ion exchange Spectrophotometry Sample preparation

"Flow Injection For Continuous Sample Introduction In Solid-substrate Room Temperature Phosphorescence"
Anal. Chim. Acta 1990 Volume 231, Issue 2 Pages 289-293
A. D. Campiglia, A. Berthod and J. D. Winefordner

Abstract: A flow injection system is described and illustrated for continuous sample introduction in two-nebulizer phosphorescence analysis. Thallium acetate (0.1M) in aqueous 50% ethanol was used as heavy-atom enhancer, and sprayed continuously on to the moving filter paper at a flow rate adjusted to deliver ~10 µL cm-2 of substrate. The method was tested with use of phenanthrene (I), pyrene and 4-aminobenzoic acid (II) as model analytes. Detection limits were in the ng range and, for I and II, calibration graphs were rectilinear over 2 orders of magnitude. Precision was 10.6 to 12.8%.
Phenanthrene Pyrene 4-Aminobenzoic acid Phosphorescence

"Flow Injection Determination Of Organic Contaminants In Water Using An Ultraviolet-mediated Titanium Dioxide Film Reactor"
Anal. Chim. Acta 1990 Volume 231, Issue 1 Pages 13-20
Gary K. -C. Low and R. W. Matthews

Abstract: A miniature spiral reactor was constructed by immobilizing a thin film of TiO2 on the inner surface of a length of PTFE tubing, then wrapping the treated tubing around a near-UV illuminating source. The reactor was installed after the injection port of a flow injection system; a diagram is presented of a second injection port, mounted in parallel, with the first, for the introduction of CO2 for calibration. Organic solutes in aqueous solution flowing along the tube were oxidized photocatalytically to CO2 that was then detected by conductivity. The effects of temp., flow rate, reactor length, O concentration. and catalyst loading are discussed. The technique was applied to the determination of alcohols, formaldehyde, oxiran and single-cell alga in sterile water for medical use. The detection limits were 10 nM-methanol and 15 nM-formaldehyde for an injection volume of 20 µL and a flow rate of 3 mL min-1. The coefficient of variation (n = 12) for 8 µM-methanol was 1.5%.
Methanol Formaldehyde Water Conductometry

"Flow Injection Spectrofluorimetric Determination Of Paracetamol"
Anal. Chim. Acta 1990 Volume 231, Issue 1 Pages 259-264
J. Martinez Calatayud, C. Gomez Benito

Abstract: Duolite A102 D anion-exchange resin (Probus) was saturated with K3Fe(CN)6 solution and slowly stirred for 30 min. The resin was separated and washed with water until a colorless filtrate was obtained. Oxidative mini-columns, prepared by introducing the resin into PTFE coils, were incorporated into the flow injection assembly (diagram given). Powdered tablets containing paracetamol (I; 0.04 to 17.6 mg l-1) were dissolved in water and the solution was applied to the mini-columns followed by direct injection into a stream of Na2CO3 - H3BO3 - KCl buffer (pH 9.94) which then merged with a stream of N,N'-dimethylformamide in an inert single-bead string reactor. Fluoresence detection was at 427 nm (excitation at 331 nm). The calibration graph was rectilinear from 0.04 to 100 mg L-1 of I and the coefficient of variation was 1.4%. Tolerance levels for foreign species are tabulated and the determination of I in several pharmaceutical formulations is discussed.
Acetaminophen Pharmaceutical Ion exchange Fluorescence

"Spectrophotometric Determination Of Ethanol In Blood Using A Flow Injection System With An Immobilized Enzyme (alcohol Dehydrogenase) Reactor Coupled To An Online Dialyser"
Anal. Chim. Acta 1990 Volume 231, Issue 1 Pages 115-119
Gabrielle Maeder, Jean-Luc Veuthey, Michel Pelletier and Werner Haerdi

Abstract: Whole blood (110 µL) which was not pre-treated was introduced into the carrier stream of sodium pyrophosphate decahydrate - semicarbazide hydrochloride - glycine - NaCl - NAD+ - water (pH 9.0) by means of a rotary valve. The mixture was passed at 650 µL min-1 to a dialyser comprising a Cuprophan membrane between two Plexiglas plates, then to a controlled-pore glass enzyme reactor with a nylon filter fabric (mesh size 100 µm) at each end, kept at 25°C. The absorbance of NADH was measured at 340 nm. The calibration graph was rectilinear from 3 to 40 µg mL-1 of ethanol, corresponding to 0.3 to 4.0 g of ethanol per 1000 g of whole blood prior to dilution. The results agreed with those from direct-injection GC.
Ethanol Whole Spectrophotometry

"Flow Injection Spectrophotometric Determination Of Acetyl-coenzyme A With Immobilized Phosphotransacetylase"
Anal. Chim. Acta 1990 Volume 232, Issue 1 Pages 281-286
Susumu Yamato and Kenji Shimada

Abstract: A method is given for immobilizing phosphotransacetylase on AF-Tresyl TOYOPEARL 650 gel. The treated gel, suspended in 0.1 M phosphate buffer, (pH 8) containing 1 mM NaN3, was packed in stainless-steel columns (1 cm x 4 mm), which were stored at 4°C. The carrier stream for flow injection analysis contained 30 mM Na2HPO4, 15 mM (NH4)2SO4 and Ellman reagent in 0.1 M borate buffer of pH 7.5 (1 mL min-1). Samples (25 µL) were injected into the carrier stream, which then passed through the gel column at 40°C In the reaction, acetyl coenzyme A was converted into acetyl phosphate and the free mercapto-compound reacted with Ellman reagent; the yellow color was detected at 412 nm. Calibration graphs were rectilinear from 4 µM to 0.4 mM, with a detection limit of 0.8 µM. At 0.2 mM, the coefficient of variation (n = 27) was 1.7%. The column was stable for 2 months, comprising ~1000 analyzes.
Acetyl-CoA Spectrophotometry

"Separation Of Rhenium By Extraction With Crown Ethers And Flow Injection Extraction-spectrophotometric Determination With Brilliant Green"
Anal. Chim. Acta 1990 Volume 232, Issue 1 Pages 287-292
Hideko Koshima and Hiroshi Onishi

Abstract: Rhenium solution (20 µg) were prepared in 2 M KOH - 10 mM K Na tartrate (10 to 30 ml), and the Re(VII) was extracted into a 10 mM dicyclohexano-18-crown-6 in 1,2-dichloroethane (5 ml, then 2 ml). The combined extracts were diluted with hexane, and the Re(VII) was back-extracted into 0.2 M phosphate buffer of pH 6.0 (6 ml, then 3 ml). The Re in the buffer was determined by flow injection, with 4 reagent lines, viz, buffer (0.4 mL min-1), water (0.4 mL min-1), ethanolic 0.15% C. I. Basic Green 1 and benzene (0.2 mL min-1). The absorbance of the benzene extract of the complex was measured at 640 nm. The calibration graph was rectilinear for up to 1.5 mg L-1 of Re(VII) in aqueous solution There was serious interference by NO3- and ClO4-; the former could be prevented by decomposition with formic acid. Large amounts of Mo(VI) did not interfere, so the method could be applied directly to, e.g., molybdenite.
Rhenium Spectrophotometry Sample preparation

"Enhancement Of Sensor Selectivity By Gas Diffusion Separation. Part 1. Flow Injection Potentiometric Determination Of Cyanide With A Metallic Silver-wire Electrode"
Anal. Chim. Acta 1990 Volume 233, Issue 1 Pages 77-84
W. Frenzel, C. Y. Liu and J. Oleksy-Frenzel

Abstract: The potentiometric response of a metallic silver-wire electrode in the presence of Ag+-complexing agents was theoretically derived on the basis of the Nernst equation and compared with experimental results. The construction of the silver-wire sensor is described and details are given of its application in gas diffusion flow injection analysis. Microporous polypropylene membranes were used to separate the donor and acceptor channels allowing almost specific determination of CN-. Gaseous interferents, e.g., H2S, SO2 and nitrogen oxides, were chemically converted before entering the gas diffusion unit. The lifetime of the sensor was more than several months. The calibration graph was rectilinear from 10 µM to 10 mM CN-, and concentration. of 0.1 M were measured for long periods without alteration of the response. The continuous corrosion process did not dissolve significant amounts of silver, which was a significant advantage over the common AgI membrane electrodes. The apparent selectivity coefficient obtained were significantly better than those reported for common CN--selective membranes.
Cyanide Potentiometry Electrode Sensor

"Flow Injection Technique For The Determination Of Low-levels Of Phosphorus In Natural Waters"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 409-416
Paul R. Freeman, Ian D. McKelvie and Barry T. Hart, Terence J. Cardwell

Abstract: A flow injection instrument for determining low concentration. of P in waters is described and illustrated. The main feature is the use of an inexpensive detector consisting of a flow cell and a photometer that incorporates a super-bright red-light emitting diode as the source and a photodiode as the detector. The procedure is a modification of the tin(II) chloride - molybdate method (cf. Tecator Application Note ASN 60-01183, Tecator AB, 1983) optimized by a modified simplex optimization method. Silicate interference (5 mg mL-1) was removed by addition of aqueous 0.1% tartaric acid. The calibration graph was rectilinear up to 100 µg L-1 of P and the detection limit was 0.6 µg l-1. The coefficient of variation were 2.9% and 0.5% for 2.0 and 50 µgl-1 of P, respectively. An inline pre-concentration anion-exchange column was used to obtain a lower detection limit of 0.1 µg l-1.
Phosphorus Environmental Spectrophotometry

"Comparative Study Of First-generation, Second-generation And Third-generation Amperometric Glucose Enzyme Electrodes In Continuous-flow Analysis Of Undiluted Whole-blood"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 321-330
Hari Gunasingham and Chin-Huat Tan, Tar-Choon Aw

Abstract: First-, second- and third-generation amperometric glucose enzyme electrodes were compared under flow injection and steady-state conditions for the monitoring of undiluted whole blood. Measurements were made in a large volume wall-jet cell (illustrated) with a four-way manual injection value, a sample loop of 25 µL or 200 µL for flow injection and steady-state modes, respectively, and a graphite counter electrode vs. Ag - AgCl. Use of first-generation electrodes, based on H2O2 detection at a Pt electrode, was limited by their instability. Second-generation electrodes in which re-oxidation of glucose oxidase occurs by a mediator are more suitable for blood analysis however the choice of mediator is important. With regard to the rectilinearity and stability, tetrathiafulvalene achieves better results than dimethyl ferrocene. Third-generatin electrodes based on tetrathiafulvaleine - teracyanoquinodimethane where direct oxidation of glucose oxidase occurs, were also useful, but display lower stability and a smaller dynamic range than second-generation devices. The calibration graphs for first, second and third-generation electrodes were rectilinear up to 10, 35 and 25 mM for steady-state analysis and 25, 80 and 60 mM for flow injection analysis, respectively.
Glucose Whole Amperometry Electrode Electrode Electrode

"Fluorimetric Sensor For The Determination Of Fluoride At The Nanograms Per Millilitre Level"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 345-352
Danhua Chen, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Fluoride solution and 2 µM binary complex of Zr and Calcein Blue were injected simultaneously from double valves with a sample loop of 500 µL into a reactor (60 cm x 0.5 mm i.d.). The ternary complex formed was retained in the fluorescence flow cell (1.1 mm i.d.) of DEAE-Sephadex resin (40 to 120 µm) and the fluorescence was measured at 405 nm (excitation at 335 nm). After the maximum fluorescence had been obtained 0.4 M HCl was injected from a third valve to elute the complex and restore the baseline. The calibration graph was rectilinear from 1 to 40 ng mL-1 of F-; coefficient of variation was 1% (n = 7). The sample throughput was 30h-1. A comparison of the cited flow-through sensor with a probe sensor for the same chemical system showed the former to be superior. The method was applied in the analysis of potable water.
Fluoride Water Fluorescence Sensor

"Indirect Flow Injection Determination Of Methadone By Atomic Absorption Spectrometry"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 433-437
R. Montero, M. Gallego and M. Valc&aacute;rcel

Abstract: Methadone (I) is determined in tablets and urine in the presence of other drugs after reduction on a Cd or Zn micro-column and flame AAS detection of the metal ions released. For urine, a 5 mL sample is made alkaline with NaOH and extracted with CH2Cl2. The residue from evaporation of the extract, is dissolved in water, and the solution is adjusted to pH 4.0 with 0.01 M acetic acid. Crushed tablet (200 mg) is dissolved in water by shaking for 55 min and filtering. The final solution (90 µL), at pH 3.3 to 4.3, is injected into a carrier stream of water (3.0 mL min-1) which proceeds to the reduction column (8.5 cm x 1.8 mm) and subsequently to the spectrometer. The calibration graph is rectilinear from 5 to 50 ng mL-1 of I. Recoveries from either column are quantitative, and coefficient of variation in urine (n = 3) are 1.2 to 3.0%. Sampling frequency is 150 h-1, and other drugs do not interfere.
Methadone Pharmaceutical Urine Spectrophotometry Sample preparation

"Determination Of Nitrate With A Flow Injection System Combining Square-wave Polarographic Detection With Online Deaeration"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 475-478
Mouna Noufi, Ch. Yarnitzky and Magda Ariel

Abstract: The catalytic reaction between NO3- and UO22+ is used to provide a simple, rapid, sensitive and accurate method for determining NO3- in river and potable water. The carrier (H2O) and reagent (0.2 M KCl - 0.02 M HCl - 0.2 mM - UO22+) streams are pumped (0.6 mL min-1) into a coil (30 cm x 0.5 mm) and 200 µL of aqueous NO3- is injected. A diagram of the apparatus is given. Voltammetry is performed with reference to an Ag - AgCl (3 M KCl) electrode, delay 4 s, scan rate 100 mV s-1 and a potential range of -0.6 to -1.1 V. The calibration graph is rectilinear for 5 to 60 µM-NO3-1, with a detection limit of 2 µM. The effect of anions on the reduction is studied.
Nitrate River Water Polarography Electrode Voltammetry

"Exchangeable Immobilized Enzyme Reactor For Enzyme Inhibition Tests In Flow Injection Analysis Using A Magnetic Device. Determination Of Pesticides In Drinking Water"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 113-117
Ralf Kindervater, Wolfgang K&uuml;nnecke and Rolf D. Schmid

Abstract: A flow injection analysis system is described for rapid automated enzyme inhibition testing. Sample in a carrier stream is mixed with a portion of enzyme immobilized on magnetic particles, and the amount of inactivated enzyme is determined. Exchange of used enzyme substrate is achieved with magnetic devices, which can be switched off to release bound material. The magnetic reactor is described and illustrated; its flow resistance is excellent. The system was applied in the determination of pesticides (carbofuran and malaoxon) in drinking water, with use of acetylcholinesterase, the activity of which was determined spectrophotometrically or electrochemically. The response was different for the two pesticides, but the limit of detection was 0.5 µg l-1. One analysis, including calibration, took 20 min.
Pesticides Water

"Determination Of Magnesium In Blood Serum Using A Flow Injection System With A Potential-scanning Electrochemical Detector Equipped With A Thin-film Deaerator"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 161-166
Rivka Goldik, Chaim Yarnitzky and Magda Ariel

Abstract: A flow injection analysis system is described involving formation of the eriochrome black T (I) - Mg complex and its detection via its adsorptive reduction current peak at a potential-scanning electrochemical detector, equipped with a static-Hg-drop electrode vs. Ag - AgCl and a novel thin-film deaerator (illustrated). The method is basically an adaptation of a previous batch method (cf. An et al., Talanta, 1985, 32, 479). Diluted serum (100 µL) is injected into a carrier stream (0.6 mL min-1) of 2% ethylenediamine solution which is merged with the reagent stream (0.4 mL min-1) containing 0.003 to 0.004% of I, and the solution is passed through a 12-cm reaction coil to the deaerator - detector device. The calibration graph is rectilinear for 0.14 µg mL-1 of Mg. Results showed good agreement with those obtained by AAS. Sampling rate is 35 h-1.
Magnesium Blood Serum Electrochemical analysis Electrode

"Integrated Photochemical Reaction/electrochemical Detection In Flow Injection Systems: Kinetic Determination Of Oxalate"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 227-232
Luis E. Leon, Angel R&iacute;os, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: A method is described for the kinetic electrochemical determination of photosensitive compounds, by using a novel electrochemical cell incorporating an optical fiber (described and illustrated). The cell allows irradiation of the sample - reagent mixture and simultaneous detection of product. The system was applied to the oxalate - Fe(III) reaction, with amperometric detection of the Fe(III) produced at +900 mV. Calibration graphs were rectilinear from 4 to 13 and 13.4 to 134 µg mL-1 of oxalate, with coefficient of variation (n = 10) of 7.8 and 3.8% at 5.3 and 13.4 µg mL-1, respectively. The detection limit was 3 µg mL-1 of oxalate. The sampling rate was 20 h-1. The kinetic parameters of the system were studied.
Oxalate Electrochemical analysis

"Phosphorescence Detection In Flowing Systems: Selective Determination Of Aluminum By Flow Injection Liquid Room-temperature Phosphorimetry"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 233-238
Yi-Ming Liu, M. R. Fernandez de la Campa, M. E. Diaz Garcia and A. Sanz-Medel

Abstract: Aluminum was determined by micelle-stabilized phosphorimetry. A three-line flow injection manifold was used, involving 1 M acetate buffer (pH 5.5) containing Na2SO3 as carrier stream, 5 mM ferron in the buffer as chelating agent, and 0.2 M hexadecyltrimethylammonium bromide in the buffer as stabilizer. Phosphorescence was measured at 596 nm (excitation at 400 nm). The calibration graph was rectilinear for 4 µg mL-1. The coefficient of variation were 2.7% for 1 µg mL-1 (n = 10). The method was reasonably selective; >20 common species did not interfere or could be masked. The method was applied without sample pre-treatment to tap-water and dialysis fluid.
Aluminum Water Dialysis Fluid Phosphorescence

"Online Determination Of Lactic Acid During Kefir Fermentation Based On A Fibre-optic Lactic Acid Biosensor And Flow Injection Analysis"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 107-112
Bernd A. A. Dremel, Wansheng Yang and Rolf D. Schmid

Abstract: Lactic acid was determined by flow injection analysis (manifold and carrier and reagent streams described), with detection with an optical-fiber lactic acid biosensor (cf. Schaffar and Wolfbeis, Biosensors, 1990, 5, 137). The sensor is based on an oxygen optrode with lactate oxidase immobilized on carbon black; the carbon black protected the optrode from interference from ambient light and sample fluorescence. By using the zone sampling technique, the calibration graph rectilinear range (0.02 to 0.5 mM) was extended up to 60 mM lactate. The coefficient of variation was 3% (n = 5) for 60 mM. The max. sampling rate was 20 h-1. The system could be used continuously for 2 days. Temperature control is important.
Lactic acid Sensor Optrode

"Simple Variable-volume Injector For Flow Injection Systems"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 253-257
J. L. Burguera, M. Burguera and C. Rivas, M. de la Guardia and A. Salvador

Abstract: The injector basically comprises a two-way solenoid valve and a simple timer circuit to activate the solenoid for various intervals. The injector can deliver sample volume from 4 to 62 µL, with a coefficient of variation generally of 0.9%. The injector was used to prepare a group of calibration graphs of varying sensitivity (for Mg with AAS detection). The construction of a calibration graph from a single standard solution is also possible.

"Multi-function Fibre-optic Sensor For The Bioluminescent Flow Determination Of ATP Or NADH"
Anal. Chim. Acta 1990 Volume 235, Issue 2 Pages 243-253
Sabine M. Gautier, Lo&ouml;ic J. Blum and Pierre R. Coulet

Abstract: Photinus-luciferin 4-monooxygenase (ATP hydrolysing) was co-immobilized with alkanal monooxygenase (FMN-linked) and NAD(P)H dehydrogenase (FMN) from Vibrio harveyi on a pre-activated polyamide membrane. The membranes was applied in the determination of ATP and NADH in a flow injection system (details described) with 0.05 M Tris buffer of pH 7.75 containing 4 mM DDT, 0.2% bovine serum albumin (BSA), 30 mM Mg acetate and 0.2 mM luciferin for determination of ATP and 0.05 M phosphate buffer (pH 7.0) containing 2 mM DDT, 0.2% BSA, 9.5 µM-decyl aldehyde and 30 µM-FMN for determination of NADH. Light emitted at the enzymatic membrane was transmitted from the light-tight flow cell through a glass-fiber bundle (1 m x 8 mm) to the photomultiplier tube of a luminometer. Calibration graphs were rectilinear from 0.25 pmol to 3 nmol of ATP and 5 pmol to 1 nmol of NADH, with coefficient of variation of 4.0 and 4.5%, respectively, when using continuous-flow measurement.
Sensor Bioluminescence

"Flow Injection Catalytic Kinetic Determination Of Manganese Using Stopped-flow And Gradient Calibration"
Anal. Chim. Acta 1990 Volume 235, Issue 1 Pages 323-327
Jiannan Yang, Chenglong Ma and Shuliang Zhang, Zhao Shen

Abstract: Sample solution was injected in to a carrier stream of borax - NaOH buffer (pH 9.5), mixed with two reagent streams of aqueous 0.5 M H2O2 and 0.1 M Tiron - 20 mM 1,10-phenanthroline, respectively, and the absorbance was monitored at 440 nm. Calibration was effected by the stopped-flow technique and only one standard was required. The calibration graph was rectilinear for up to 640 nM-Mn(II) and no interference was observed from Zn(II), Co(II), Ni(II), Fe(III), Cd(II) and Cu(II). The method was applied in the determination of Mn2+ in resevoir water; results agreed well with those by an alternative catalytic method. Throughput was 40 samples h-1.
Manganese

"Determination Of Quinine And Quinidine By Continuous-flow Chemiluminescence"
Anal. Chim. Acta 1990 Volume 236, Issue 2 Pages 463-468
Ioanna I. Koukli and Antony C. Calokerinos

Abstract: A chemiluminescence analyzer. [Koukli et al., Analyst (London), 1988, 113, 603] with an air-segmented continuous-flow manifold (diagram given) was used to determine quinine and quinidine by their sensitizing action on the reaction between Ce(IV) and SO32-. The Ce(IV) solution in 0.1 M H2SO4 was segmented with air before introduction of the analyte solution also in 0.1 M H2SO4. The stream was de-bubbled, then mixed with the SO32- solution before entering the coil for generation of chemiluminescence. The calibration graph for either analyte (log-log scale for quinine) was rectilinear from 5 to 500 µg mL-1, and the analysis rate was 40 h-1. The limit of detection was 0.64 and 1.6 µg mL-1 for quinidine and quinine, respectively. The method was successfully applied to pharmaceuticals.
Quinine Quinidine Pharmaceutical Chemiluminescence

"Determination Of Chromium By Online Preconcentration On A Poly (hydroxamic Acid) Resin An Flow Injection Atomic Absorption Spectrometry"
Anal. Chim. Acta 1990 Volume 236, Issue 2 Pages 469-473
Ajay Shah and Surekha Devi

Abstract: Seven poly(hydroxamic acid) resins [Analyst (London), 1985, 110, 501] were evaluated for LC separation of Cr(III) from U(VI) and from multi-component mixtures. Columns (17 cm x 5 mm) containing the resins in H+ form were used, and the flow rate for sorption and elution was 1 mL min-1. At pH 5, U(VI), Fe(III), Zn and Cu(II) were retained on the resin, but ~80% of the Cr(III) passed through. Retained U(VI) was eluted by 1 M HCl, Zn and Cu(II) by 0.1 M HCl and Fe(III) by 3 M HCl. Cross-contamination was observed between Zn and Cu. Tervalent Cr could also be determined by flow injection flame AAS with use of a column (4 cm x 2.5 mm) of poly(hydroxamic acid) resin and a carrier stream of 0.2 M acetate buffer (pH 2) for pre-concentration.; the Cr(III) was then eluted with 1 M HCl for AAS at 357.9 nm. The calibration graph was rectilinear for 10 µL portions of solution containing 20 to 100 ng mL-1 of Cr(III). The flow injection method was used to determine Cr(III) in seawater at pM concentration.
Chromium Sea Spectrophotometry

"Kinetic Determination Of Sulfonamides At The Millimolar Level By The Continuous Addition Of Reagent Technique"
Anal. Chim. Acta 1990 Volume 237, Issue 2 Pages 353-359
M. M&aacute;rquez, M. Silva and D. P&eacute;rez-Bendito

Abstract: A sulfonamide solution was mixed with 5 mM 1-naphthol in ethanol and 1.0 M acetic acid - Na acetate buffer (pH 4.15) and the mixture was diluted with water. The reaction was developed by continuous addition of 1 M NaNO2 at 0.5 mL min-1 with stirring at 200 rpm. The production of an azo dye was monitored at 470 nm. The calibration graph was rectilinear from 3 to 30 µM. The coefficient of variation for 18.7 µM-sulfonamide was 1.0% (n = 11) and the sampling rate was 25 h-1. The detection limit was 1.5 to 2.0 µM. The method is more sensitive than a reported flow injection method and more rapid than the conventional photometric micellar method. The technique was used for the determination of sulfonamides in pharmaceuticals.
Sulfonamides Pharmaceutical

"Enzyme Co-immobilization For The Sequential Determination Of Lactic Acid And Glucose In Serum"
Anal. Chim. Acta 1990 Volume 238, Issue 2 Pages 411-415
M. T. Morales, P. Linares, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: Lactic acid (I) and glucose (II), in a phosphate buffer carrier solution (pH 8.5), were determined by flow injection analysis in a reactor of immobilized glucose-6-phosphate dehydrogenase, hexokinase and L-lactate dehydrogenase at pH 8.0. The products, NADH and NADPH, from I and II, respectively, were monitored at 340 nm. Calibration graphs were rectilinear from 10 to 400 and 2 to 100 µg mL-1 of I and II, respectively, with corresponding coefficient of variation (n = 11) of 1.63 and 2.30%. Recoveries were 88.84 to 118.4% for I and 92.72 to 110.3% for II in serum. Mixtures of the analytes (up to 1:10) could be resolved.
Lactic acid Glucose Blood Serum

"Spectrophotometric Determination Of Silicate With Rhodamine B By Flow Injection Analysis"
Anal. Chim. Acta 1990 Volume 239, Issue 1 Pages 151-155
F. M&aacute;s, J. M. Estela and V. Cerd&aacute;

Abstract: A method is proposed based on the formation of an ion pair between molybdosilicic acid and rhodamine B (C. I. Basic Violet 10). Sample solution was reacted with 24 mM molybdate solution in 0.2 M HNO3 and 10 mM rhodamine B solution in 1 M HNO3 containing 0.1% poly(vinyl alcohol) and the absorbance was measured at 590 nm. The calibration graph was rectilinear from 0.2 to 2.0 mg L-1 of silicate. Tolerance levels for foreign ions are given. The sampling rate was 40 h-1. The method was applied in the determination of silicate in waters.
Silicate Environmental Spectrophotometry

"Comparison Of The Powell And Simplex Methods In The Optimization Of Flow Injection Systems - Simulation On Modelled Experimental Surfaces And Experimental Optimizations"
Anal. Chim. Acta 1990 Volume 241, Issue 1 Pages 31-42
M. del Valle, M. Poch, J. Alonso and J. Bartroli

Abstract: In the determination of NH3 by the indophenol reaction, both methods provided optimum conditions. However, the Powell algorithm needed fewer evaluations for the determination of maximum sensitivity and throughput and was efficient at the beginning of the process, needing the modification of only one independent variable. With the optimized system, the limit of detection was 5 ng mL-1 and the coefficient of variation (n = 32) for 3 µg mL-1 was 1.5% (throughput 70 per h). The calibration range covered 0.03 to 6 µg mL-1.
Ammonia Spectrophotometry

"Compensation Of Calibration Graph Curvature And Interference In Flow Injection Spectrophotometry Using Gradient Ratio Calibration"
Anal. Chim. Acta 1990 Volume 241, Issue 1 Pages 15-22
Shihua Fan and Zhaolun Fang

Abstract: The gradient ratio calibration method employing a single standard (proposed for flow injection AAS by Sterling et al.) has been applied to the flow injection spectrophotometric determination of Cl- by the Hg(SCN)2 - Fe(III) method. The calibration method was also applied to overcome the interference from Fe(III) (150 ppm) in the determination of PO43- (6 ppm) by the molybdenum blue method.
Chloride Spectrophotometry

"Compensation Of Calibration Graph Curvature And Interference In Flow Injection Spectrophotometry Using Gradient Ratio Calibration"
Anal. Chim. Acta 1990 Volume 241, Issue 1 Pages 15-22
Shihua Fan and Zhaolun Fang

Abstract: The gradient ratio calibration method employing a single standard (proposed for flow injection AAS by Sterling et al.) has been applied to the flow injection spectrophotometric determination of Cl- by the Hg(SCN)2 - Fe(III) method. The calibration method was also applied to overcome the interference from Fe(III) (150 ppm) in the determination of PO43- (6 ppm) by the molybdenum blue method.
Chloride Spectrophotometry

"Automatic Calibration And Dilution In Unsegmented Flow Systems"
Anal. Chim. Acta 1992 Volume 264, Issue 2 Pages 265-273
M. Agudo, A. R&iacute;os and M. Valc&aacute;rcel

Abstract: Automatic preparation of calibration solution was incorporated into a manifold by a switching-diverting valve, thus the calibration and determination steps were coupled and automated. The method was applied in the determination of NO2- with spectrophotometric monitoring at 540 nm using sulfanilamide and N-(1-naphthyl)ethylenediamine. The system may be useful in process control. An open-closed flow system allowing variable volumes of standard calibration solution to be introduced and automatically diluted was used to carry out automatic calibrations in unsegmented flow systems. A dilution loop was thus established in which its final homogenized volume was used as diluted sample or calibrant solution in the main flow system. The performance of the dilution loop was tested both in injection and in completely continuous-flow systems and was found to be appropriate for anal. process control.
Nitrite Spectrophotometry

"Use Of Submicrolitre-volume Samples For Extending The Dynamic Range Of Flow Injection Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 85-95
I. L&oacute;pez Garc&iacute;a, P. Vi&ntilde;as, N. Campillo and M. Hern&aacute;ndez C&oacute;rdoba*

Abstract: Three computer-controlled flow injection manifolds were compared for extending the linear range of flame-AAS. All manifolds were based on metering very small volumes into a slow moving carrier. At the end of the injection the flow rate of the carrier was increased. The manifolds were equipped with an additional channel to compensate for the difference between the flow delivered by the pump and the nebulizer uptake rate. The most satisfactory results were obtained by performing a single metering stage with a peristaltic pump fitted with a 0.38 mm i.d. bore tube. The exact position of the rollers at the beginning of the metering stage was controlled by a simple optical device. Volumes as low as 0.02 µL were injected into the system by using a 0.15 s metering time at 0.56 rpm. Dilutions of 20 000-fold were achieved with a repeatability of ±1.1-3.3%.
Magnesium Spectrophotometry

"Preconcentration And Flow Injection Multivariate Determination Of Priority Pollutant Chlorophenols"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 238-245
F. Navarro-Villoslada, L. V. P&eacute;rez-Arribas, M. E. Le&oacute;n-Gonz&aacute;lez* and L. M. Polo-D&iacute;ez

Abstract: Water (500 ml) containing up to 200 ppb of chlorophenols was acidified with 10 mL 3 M HCl and passed through a XAD-4 column (1.2 g of resin; 65 mm x 5 mm i.d.) at 4 ml/min. The chlorophenols were eluted with 10 mL methanol. The eluate was evaporated to dryness and the residue was dissolved in 10 mL 0.01 M borate buffer of pH 9.1. A 250 µL portion of the solution was injected into a borate buffer carrier stream (1.5 ml/min) and merged with a 1.5 g/l tetrabutylammonium nitrate stream (1.2 ml/min). The flow passed through a reaction coil (30 cm x 0.3 mm i.d.) to allow chlorophenol-tetrabutylammonium ion-pairs to form. The ion-pairs were extracted into CHCl3 by merging with a CHCl3 stream (0.6 ml/min). After passing through the extraction coil (130 cm x 0.3 mm i.d.) the phases were separated in a membrane phase separator. The spectra of the organic phase were recorded every 0.6 s from 200-430 nm. The first derivative spectra was calculated. Calibration standards contained up to 10 mg/l of chlorophenols. Three multivariate methods were used, namely, classical least squares, partial least squares and a Kalman filter. The method was used to analyze tap water spiked with chlorophenols up to 180 µg/l. All three multivariate calibration methods gave acceptable errors (~e;5%) for each chlorophenol (listed) except 2,4,6-trichlorophenol (~e;15%).
Phenols, chloro Water Spectrophotometry Spectroscopy Sample preparation

"Shipboard Flow Injection Determination Of Seawater PH With Spectrophotometric Detection"
Anal. Chim. Acta 1995 Volume 309, Issue 1-3 Pages 259-270
Richard G. J. Bellerby, David R. Turner, Geoffrey E. Millward and Paul J. Worsfold

Abstract: Seawater was pumped at 12 ml/min through a flow-cell, and using stopped-flow analysis a zero reading was obtained for 30 s at 433 nm and 558 nm. After flow-restart, ~8.3 µL of an 0.8-0.9 absorbance (at 558 nm) solution of phenol red indicator (Na salt) in seawater was added and the solutions mixed in a 1 m reaction coil. The flow was again stopped, and after a 30 s delay, the absorbances at 433 nm and 558 nm were obtained. Over the range 18-27°C an error of ±0.001 pH/°C was estimated. Sample alkalinities were calculated from pCO2 and total CO2 parameters obtained via carbonic acid dissociation constants (details given), the data demonstrating internal consistency with sample pH. Over a 3 h period, a weighted standard deviation of ±0.005 pH units was obtained (n = 106) with associated precisions of ±2 µatm of pCO2 and ±1 µmol total CO2/kg, respectively. No method calibration was necessary.
pH Sea Spectrophotometry

"A New Flow Injection Single-standard Calibration Method For Flame Atomic Absorption Spectrometry Based On Dilution By Microsample Dispersion"
Anal. Chim. Acta 1996 Volume 326, Issue 1-3 Pages 49-55
Zhaolun Fang*, Shukun Xu and Xuesheng Bai

Abstract: A FIA manifold equipped with computer controlled stepper-motor-driven peristaltic pumps and mixing coil is described for metering volumes of a standard solution into a 100 µL sample loop for calibrating an atomic absorption spectrophotometer. The system was used to prepare a calibration graph for the determination of Mg at 285.2 nm. There was no statistically significant difference between calibration graphs prepared by the single standard and multiple standards methods.
Magnesium Spectrophotometry

"Flow Microcalorimeter Auto-calibration For The Analysis Of Immobilized Enzyme Kinetics"
Anal. Chim. Acta 1997 Volume 355, Issue 1 Pages 63-67
V. Stefuca*, A. Welwardov&aacute; and P. Gemeiner

Abstract: A new calibration procedure of a flow microcalorimeter (FMC) for the direct investigation of immobilized enzyme kinetics was developed. The procedure is based on the use of a flow-through microcalorimetric column packed with the immobilized enzyme adapted to the differential reactor system with infinite flow recirculation. The true reaction rate is determined from the substrate consumption as calculated from the decrease in thermometric response. The response is transformed to the substrate concentration based on a microcalorimeter column calibration using known substrate concentrations. The method was experimentally verified using the invertase immobilized by biospecific binding on concanavalin A - cellulose conjugates. From the measurement of the sucrose hydrolysis in the FMC, all kinetic parameters of immobilized invertase, Vmax, Km, and Ki were estimated. Results were compared to those obtained by the simultaneous spectrophotometric determination of the reactant concentrations. Both techniques gave equivalent results of reactant concentrations and kinetic parameters.
Calorimetry

"Simultaneous Calibration In Flow Injection Analysis Using Multiple-injection Signals Evaluated By Partial Least Squares"
Anal. Chim. Acta 1998 Volume 363, Issue 2-3 Pages 183-189
Karsten Sch&ouml;ngarth and Bernd Hitzmann*

Abstract: In this contribution, a new calibration technique for flow injection analysis is presented. The technique is based on a multiple-injection system complemented with multivariate evaluation. A standard the sample and another standard solution are injected in a fast sequence. A partial mixing of the solutions occurs due to dispersion. However, the overlapping measurement signals can be deconvoluted reliably employing partial least-squares regression. The simultaneous calibration technique enables a fast adaptation to changes in the reaction system, while the time lost by rapid threefold injection and the signal evaluation is minimal. Applying simultaneous calibration the change of the sensor sensitivity is considered inherently. To test the simultaneous calibration technique, it was applied to measurements of a flow injection system for the determination of glucose while the temperature of the reaction coil was changed.
Glucose

"Flow Injection Standard Subtraction Method For The Determination Of Iron(III) Based On Its Catalytic Effect And Inhibition Of EDTA"
Anal. Chim. Acta 1998 Volume 374, Issue 2-3 Pages 303-307
Tsuyako Watanabea, Norio Teshimaa, Shigenori Nakanob and Takuji Kawashimaa,*

Abstract: A new approach for the flow injection catalytic determination of 10^-6 M levels of iron(III) is proposed. This method is based on the catalytic effect of iron(III) on the oxidative coupling of p-anisidine with N,N-dimethylaniline to form a blue compound (λmax=735 nm) in the presence of hydrogen peroxide and 1,10-phenanthroline as an activator, and the inhibitory effect of EDTA on the iron(III)-catalyzed reaction. The concentration. of iron(III) can be determined from only two flow signals which are obtained by injecting the iron(III) and iron(III) plus EDTA solutions into the flow lines without a calibration graph for iron(III); this procedure may be called standard subtraction. The proposed method permits the anal. of 12 samples per h (24 peaks per h) and was successfully applied to the determination of iron in standard iron ore samples.
Iron(III) Iron Spectrophotometry

"Continuous-dilution Calibration Technique For Flame Atomic Absorption Spectrophotometry"
Talanta 1984 Volume 31, Issue 1 Pages 9-14
J. F. Tyson and J. M. H. Appleton

Abstract: The rapid, automatic calibration procedure presented is based on a flow injection technique (mixing-chamber gradient method); it requires no curve-fitting approximations, and extends over the whole working concentration. range of the analyte, irrespective of the shape of the conventionally obtained calibration graph. The theory of the method and a schematic diagram of the apparatus are given. Results for the determination of Mg, Cr and Ni are presented and discussed. With well designed apparatus, deviations of <1% should be attainable; deviations of <4% were obtained.
Cadmium Magnesium Nickel Spectrophotometry

"Evaluation Of Single-point Calibration In Flow Potentiometric Stripping Analysis"
Talanta 1986 Volume 33, Issue 11 Pages 883-888
Boy H&oslash;yer and Lars Kryger

Abstract: The use of a single-point calibration in flow potentiometric stripping analysis has been evaluated. For a number of sample matrices, the results obtained by calibration methods agree with those obtained by using standard addition. The most serious source of systematic error is inhibition in the deposition step, caused by organic surfactants and chelating agents in the sample matrix. Consequently, the use of the calibration method should be restricted to samples which have been totally mineralized. It is shown that most sources of systematic error in the calibration method will result in underestimation of the analyte concentration.
Potentiometric stripping analysis

"Diode-array Detectors In Flow Injection Analysis. Mixture Resolution By Multi-wavelength Analysis"
Talanta 1987 Volume 34, Issue 12 Pages 987-993
M. Blanco*, J. Gene, H. Iturriaga, S. Maspoch and J. Riba

Abstract: In the use of diode-array spectrophotometry for multi-component determination by flow injection analysis, aspects considered are(I) the recording of reproducible spectra at max. sensitivity and(II) the mathematical processing of the spectral data to determine the various components. Three data processing procedures are assessed, viz: (a) a linear simultaneous-equation system, (b) a multi-component analysis computation program (Hewlett-Packard), and (c) graphical multi-wavelength linear regression analysis. The test analysis was simultaneous determination of Fe(II) and Fe(III) with 1,10-phenanthroline - sulfosalicylic acid reagent with measurements at 486 and 510 nm. Data processing procedures (b) and (c) yielded similar and satisfactory results.
Iron(2+) Iron(III) Spectrophotometry

"7,7,8,8-Tetracyanoquinodimethane Chemiluminescence Sensitized By Rhodamine B On Surfactant Bilayer Membrane Assemblies For Determination Of Sulfide By A Flow Injection Method"
Talanta 1989 Volume 36, Issue 4 Pages 505-508
Qian Xue-Xin, Guo Yue-Ying, Masaaki Yamada*, Eigo Kobayashi and Shigetaka Suzuki

Abstract: Optimum conditions have been established for the cited analysis. The two reagent streams (7.5 mL min-1) comprising 0.1 mM 7,7,8,8-tetracyanoquinodimethane - 0.5 mM rhodamine B - 40% acetonitrile and 1 mM dioctadecyldimethylammonium chloride - 1 mM NaOH, respectively, were separately heated in 1-m PTFE coils at 57°C. The streams were then mixed before injection of sample solution (30 µL) and measurement of the chemiluminescence signal by using a photomultiplier tube. The calibration graph was rectilinear from 0.05 to 5 µM-S2- ,and the detection limit was 0.01 µM. The coefficient of variation (n = 19) was 3.0% for 0.3 µM-S2-. The effects of various common ions were studied. Bivalent Mn and Fe and species forming a ppt. with S2- interfere. The method was applied to determine S2- in hot-spring water, and results agreed with those obtained by iodimetry.
Sulfide Environmental Chemiluminescence

"Sandwich Standardization In Flow Injection Analysis"
Talanta 1989 Volume 36, Issue 5 Pages 612-614
Angel Rios, M. D. Luque de Castro and Miguel Valcarcel

Abstract: The basic flow injection analysis configuration for sandwich standardization is illustrated. Sample and calibration solution fill the loops of two valves in an injection unit (illustrated), and, by continuous injection of the contents of both loops, sample and standards are introduced in a standard - sample - standard sequence. The resulting sandwich of plugs then merges with the reagent, thus creating three reaction zones each providing a signal on passage through the detector. The application of the method is demonstrated with the determination of formaldehyde in water by using the SO32- - pararosaniline system with spectrophotometric monitoring at 578 nm. Advantages of derivative over normal recordings are discussed. The basic flow injection analysis configuration for sandwich standardization is illustrated. Sample and calibration solution fill the loops of two valves in an injection unit (illustrated), and, by continuous injection of the contents of both loops, sample and standards are introduced in a standard - sample - standard sequence. The resulting sandwich of plugs then merges with the reagent, thus creating three reaction zones each providing a signal on passage through the detector. The application of the method is demonstrated with the determination of formaldehyde in water by using the SO32- - pararosaniline system with spectrophotometric monitoring at 578 nm. Advantages of derivative over normal recordings are discussed.
Formaldehyde Water

"Photometric And Amperometric Flow Injection Determination Of Triazolam And Clotiazepam"
Talanta 1989 Volume 36, Issue 7 Pages 761-765
R. M. Alonso*, R. M. Jimenez, A. Carvajal, J. Garcia and F. VicenteL. Hernandez

Abstract: For spectrophotometric determination, the carrier solution for triazolam (I) and clotiazepam (II) were aqueous 13% methanol and 0.1 M H2SO4, respectively, at flow rates of 5.0 and 5.4 mL min-1. Sample volume was 75 µL and delay coil dimensions were 37 cm x 0.58 mm i.d. for I and 35 cm x 0.58 mm i.d. for II. Calibration graphs were rectilinear for 3 to 55 µM-I at 228 nm and for 31 to 502 and 6 to 125 µM-II at 390 and 260 nm, respectively. For amperometric determination, the carrier solution for I and II were acetate buffer (pH 4.7) in 10% methanol and 0.1 M H2SO4, respectively, at flow rates of 4.5 and 6.4 mL min-1, sample volume were 106 and 75 µL for I and II, respectively, and delay coil dimensions were 50 cm x 0.58 mm i.d. for II and 16 cm x 0.58 mm i.d. for I. Detection was at -1.125 and -0.950 V for I and II, respectively, at a hanging-Hg-drop electrode vs. a SCE. Calibration graphs were rectilinear for 6 to 116 µM-I and 16 to 162 µM-II. Both methods were applied in the analysis of phamaceuticals.
Triazolam Clotiazepam Pharmaceutical Amperometry Electrode Spectrophotometry

"Evaluation Of The Analytical Use Of The Manganese-catalysed Malachite Green - Periodate Reaction By The Stopped-flow Technique"
Talanta 1989 Volume 36, Issue 11 Pages 1091-1094
M. C. Quintero, M. Silva and D. Perez-Bendito

Abstract: Sample solution contained 2 to 200 ng mL-1 of Mn(II) and 0.1 M NaIO4 (0.7 ml); the reagent solution consisted of 0.22 mM malachite green (2.5 ml) and acetate buffer (pH 3.8; 4 ml). The solution were diluted to volume and mixed, and the decrease in absorbance was measured at 615 nm. The effect on reaction rate of temp., concentration. of reagents and pH were investigated; the detection limit depended on the presence of the activator nitrilotriacetic acid. The calibration graphs were rectilinear from 0.1 to 15 and 0.5 to 100 ng mL-1 of Mn(II), and precision was 2% (n = 11). The proposed method was more sensitive and rapid than reference batch and flow injection methods.
Manganese

"Determination Of Ortho- And Pyrophosphates In Waters By Extraction Chromatography And Flow Injection Analysis"
Talanta 1990 Volume 37, Issue 10 Pages 889-894
B. Ya. Spivakov, T. A. Maryutina, L. K. Shpigun, V. M. Shkinev and Yu. A. Zolotov, E. Ruseva and I. Havezov

Abstract: A flow injection manifold is described which includes an extraction mini-column and a post-column spectrophotometric detector. The sum of ortho- and pyro-phosphate was determined in an aqueous sample by hydrolysis of the pyrophosphate at 50°C using inorganic pyrophosphatase, then the solution was mixed with a stream of 1 M HNO3 before passage through a column of Chromaton N-AW-HMDS modified with dioctyltin dichloride. The column was washed with water and Tris - HCl buffer for 1 min, and total orthophosphate was eluted with 0.5 M HCl. The orthophosphate was determined by mixing the solution with 1 M HNO3, pumping the stream through the column and elution with HCl as before, followed by monitoring the absorbance at 660 nm of the molybdenum blue produced in a reaction coil. For a sample volume of 6 ml, the calibration graph was rectilinear from 5 to 100 ng mL-1 of P, and the detection limit was 0.3 ng mL-1. The recovery of the ions was >96%. The method was used for the analysis of river water.
Phosphate Pyrophosphate River Spectrophotometry Sample preparation

"Determination Of The Flotation Collector Ethyl Xanthate By Flow Injection Analysis"
Talanta 1990 Volume 37, Issue 11 Pages 1067-1070
Miloslav Kopanica, Vra Star&aacute; and Anton&iacute;n Troj&aacute;nek

Abstract: A flow-through cell suitable for voltammetric detection was constructed from Plexiglas (diagram given) containing a carbon-paste disc working electrode of silica gel - ceresine - graphite (14:43:43) and a Ag - AgCl reference electrode. Sample solution containing ~5 mg L-1 of K ethylxanthate was injected into the carrier stream of 0.1 M KNO3 (0.6 mL min-1) and voltammetric scanning (0.5 V s-1) was performed from -0.15 V to +0.9 V. Calibration graphs were rectilinear for 0.1 to 10 mg L-1 of ethylxanthate. The detection limit was 0.4 mg l-1. Interference from cations was overcome by addition of EDTA. The method was successfully applied to the analysis of ore.
Ethyl xanthate Geological Voltammetry Electrode

"Determination Of Thiamine By Continuous-flow Chemiluminescence Measurement"
Talanta 1990 Volume 37, Issue 11 Pages 1043-1048
Nikos Grekas and Antony C. Calokerinos*

Abstract: Sample solution stream was mixed with the oxidant stream of 5 mM ferricyanide solution in 1 M NaOH. The mixed stream was pumped to a spiral glass flow cell in front of a photomultiplier; the output of the photomultiplier tube was fed to an operational amplifier and then to a recorder. The effect on chemiluminescence intensity of sample and oxidant flow rates and concentration. of ferricyanide and alkali solution were investigated. Calibration graphs were rectilinear from 20 to 500 µM-thiamine nitrate or hydrochloride. The detection limit was 9 µM. In the analysis of pharmaceutical formulations, ascorbic acid interfered.
Thiamine Pharmaceutical Chemiluminescence

"Indirect Determination Of Chloride And Carbonate By Reversed Flow Injection Analysis Coupled With Atomic Absorption Spectrometry And Inline Preconcentration By Precipitation"
Talanta 1990 Volume 37, Issue 12 Pages 1123-1128
Fatima T. Esmadi, Maher A. Kharoaf and Abdulrahaman S. Attiyat*

Abstract: Chloride and CO3-1 were determined by precipitation as AgCl and CaCO3 in a Tygon tube containing glass beads, dissolution of the ppt. in Na thiosulfate solution and HCl, respectively, and analysis by reversed flow injection AAS. The signal obtained for the cation was proportional to the concentration. of anion in the sample. Calibration graphs were rectilinear from 0.5 to 16 and 1 to 14 µM for Cl- and CO32-, respectively, with detection limits of 0.3 and 0.5 µM. Corresponding recoveries and coefficient of variation were 94 and 3.7 and 92 and 1.6% (n = 10). Thiocyanate, I- and Br- interfered with Cl- and PO43- interfered with CO32-. The method was fairly selective and sensitive and had a lower detection limit and higher sampling frequency than other methods.
Chloride Carbonate Spectrophotometry

"Spectrophotometric Determination Of Palladium With Sulfochlorophenolazorhodanine By Flow Injection"
Talanta 1990 Volume 37, Issue 3 Pages 329-336
Paul M. Shiundu, Peter D. Wentzell and Adrian P. Wade*

Abstract: A computer-controlled flow injection system (Betteridge et al., Anal. Chem., 1986, 58, 2258) with 70 µL injection loop, peristaltic pumping and a 30 µL 1-cm pathlength detection cell is used with diode-array detection at 488 nm for determination of Pd at pH 5. The sample injection medium was 1 mM HCl, the reagent stream contained the Na salt of the cited reagent at 0.94 mM buffered with pH 2 Universal buffer and 0.2 M NaOH and the carrier stream was aqueous solution The rectilinear calibration range was from 0.045 to 30 µg mL-1. Interference studies are reported for 19 metal ions.
Palladium Spectrophotometry

"Manual And Flow Injection Spectrophotometric Assay Of Thiols, Based On Their S-nitrosation"
Talanta 1991 Volume 38, Issue 3 Pages 283-289
Krishna K. Verma and Kent K. Stewart*, Archana Jain, Dayashanker Gupta and Sunil K. Sanghi

Abstract: For the manual and flow injection methods (described), thiols are treated with NaNO2 and HCl, the excess of HNO2 is destroyed by addition of ammonium sulfamate, and the S-nitrosothiols are hydrolyzed with Hg(II); an azo-dye is formed by the reaction of the released HNO2 with sulfanilamide and N-(1-naphthyl)ethylenediamine. Detection is at 544 nm. Since the final step depends on the HNO2 liberated and not on the particular thiol being determined, the calibration graphs should be identical for all thiols. The manual method is about 4-fold more sensitive than the flow injection method, but the latter has a high sample rate and is less susceptible to interference by tryptophan. The method is applicable to many thiols including aromatic thiols and amino-acids, but cannot be used for many sterically hindered thiols.
Thiols Spectrophotometry

"Spectrophotometric Determination Of Mixtures Of 2-, 3- And 4-hydroxybenzaldehydes By Flow Injection Analysis And UV/VIS Photodiode-array Detection"
Talanta 1994 Volume 41, Issue 1 Pages 59-66
Lars N&oslash;rgaard and Carsten Ridder*

Abstract: Samples (77 µL) containing 2-hydroxybenzaldehyde (I), 3-hydroxybenzaldehyde (II), 4-hydroxybenzaldehyde (III) or mixtures thereof in aqueous 10% ethanol and a modified Britton-Robinson buffer (pH 11.4) as the reagent solution were injected simultaneously into the flow injection apparatus (described) with a modified Britton-Robinson buffer (pH 4.5) as the carrier (0.375 ml/min) and a 8 µL flow cell. Spectrometric scanning (250-450 nm, every 2 nm) commenced 20 s after the injection and continued with a 1 s interval in 88 s. Each sample injection provided a data matrix consisting of 89 x 101 absorbances, containing both the acidic and basic characteristics of the sample injected. A least-squares algorithm was used to predict concentration in unknown samples. No assumptions about the qualitative mixture composition were necessary. Four data types were used in the least-squares modeling: unfolded raw data; acidic spectra; basic spectra; and first spectral derivative of the raw data. The prediction errors obtained for I-III were comparable to literature values. A graphic method was developed.
2-Hydroxybenzaldehyde 3-Hydroxybenzaldehyde 4-hydroxybenzaldehyde Spectroscopy Spectrophotometry

"Simultaneous Determination Of Penicillin And Ampicillin By Spectral Fiberoptic Enzyme Optodes And Multivariate Data-analysis Based On Transient Signals Obtained By Flow Injection Analysis"
Talanta 1995 Volume 42, Issue 12 Pages 2065-2072
J&uuml;rgen Polster*, Gertraud Prestel, Markus Wollenweber, Gerolf Kraus and G&uuml;nter Gauglitz

Abstract: A multicomponent detection system using optical biosensors and flow injection analysis is described. The analysis of mixtures containing penicillin and ampicillin was realised by evaluating dynamic measurements of Phenol Red spectra in penicillinase optodes in combination with a diode array spectrometer. A variety of optodes has been produced by changing the composition of the receptor gel and the working pH. A set of characteristic quantities (describing dynamic and static features) could be obtained for each optode. These were used to compare the predictivity of classical multivariate calibration methods as well as of an artificial neural network, In addition, different algorithms were applied for the evaluation of the spectral data in order to select the most appropriate method for feature extraction. In consequence, the information obtained from the multivariate calibration models was used to set up an optimal sensor array consisting of four optodes with different types of penicillinase at different working pH. (25 references)
Penicillin Ampicillin Sensor Sensor

"Determination Of Ion-selective Electrode Characteristics By Non-linear Curve Fitting"
Talanta 1997 Volume 44, Issue 10 Pages 1847-1858
Paddy Kane and Dermot Diamond*

Abstract: A simple practical method of determining potentiometric selectivity coefficients of ion-selective electrodes (ISEs) is described in which electrode characteristics (slope, potentiometric selectivity coefficients and cell constant) can be determined by fitting the experimental data obtained using the fixed interference (FI) method to an appropriate model by non-linear least-squares regression. The proposed method is simple to implement practically, and data processing can be easily achieved through use of the optimization add-on, Solver, bundled with Microsoft Excel. The flexibility of the method is demonstrated by modelling the response of a valinomycin potassium-selective electrode with the Nikolskii-Eisenman equation and a recently proposed alternative to the Nikolskii-Eisenman equation for cases where the ionic charges on the primary and interfering ions are unequal.
Lithium Blood Serum Electrode Electrode

"Extended Calibration Of Flame Atomic Absorption Instruments By A Flow Injection Peak Width Method"
Analyst 1984 Volume 109, Issue 3 Pages 319-321
Julian F. Tyson

Abstract: In the cited calibration method exemplified for Mg, a standard solution (~100 µL of 1, 10, 100 or 1000 ppm, the last two being higher concentration. of Mg than can be used in the conventional method) is injected into distilled water flowing at 6.9 mL min-1 through a PTFE tube (0.58 mm i.d., of minimum length to enable thorough mixing) to the nebulizer coupled to a flame AAS system. The measured peak width is proportional to the log. of a function of concentration. The basis of this method is that the peaks are exponential in shape. The peak-width method is less accurate than the conventional method.
Magnesium Spectrophotometry

"Graphite Paste Based Enzymatic Glucose Electrode For Flow Injection Analysis"
Analyst 1988 Volume 113, Issue 5 Pages 735-738
Wojciech Matuszewski and Marek Trojanowicz

Abstract: The electrode was prepared from a mixture of graphite powder, silicone oil and glucose oxidase, and was used with a wall-jet flow-through cell at +0.9 V vs. Ag - AgCl. Response was rectilinear up to 30 mM glucose (40 µL injection) with a detection limit, for 750 µL injections, of 20 µM in 0.1 M phosphate buffer (pH 6.5) at 1 mL min-1. In the analysis of soft drinks, recoveries of glucose added at the 2 to 20 mM level were between 91.8 and 105.1%. Up to 120 samples h-1 could be analyzed.
Glucose Soft drink Amperometry Electrode Electrode

"Factors Concerning The Design And Calibration Of An Amperometric Enzyme Electrode System For The Flow Injection Analysis Of Cholesterol"
Analyst 1988 Volume 113, Issue 9 Pages 1419-1422
G. J. Moody, G. S. Sanghera and J. D. R. Thomas

Abstract: Cholesterol oxidase (5 mg mL-1 in phosphate buffer) is immobilized on a nylon mesh, which is then attached to a smooth Pt electrode. A serum sample (0.5 ml) is injected into a stream (2.3 mL min-1) of 100 µM-NaH2PO4 (pH 7.0) containing 1% of Triton X-100 in a flow injection system. A three-electrode detector system (Metrohm EA1102) is used. The electrodes are operated at +600 mV vs. Ag - AgCl. Factors affecting the enzyme electrode lifetime were studied. The calibration graph was rectilinear from 10 µM to 1 mM cholesterol.
Cholesterol Blood Serum Amperometry Clinical analysis Electrode Electrode

"Inverse Spectrophotometric Detection In Flow Injection Analysis. Determination Of Nitrite Using Cerium(IV) As The Chromophore"
Analyst 1988 Volume 113, Issue 10 Pages 1597-1599
Thomas P. Lynch

Abstract: In the flow injection system a sample was injected into water (2 mL min-1), which was mixed with cerium(IV) ammonium sulfate (20 g l-1; 0.6 mL min-1) in 0.5 M H2SO4 and passed through a mixing coil (2.3 m). The absorbance of the solution was monitored at 407 nm. The calibration graph of decrease in absorbance vs. concentration. of NO2- was not rectilinear from 200 to 1000 mg l-1, but the fourth-degree polynomial regression curve showed r >0.9999. The range of application could be extended from 10 to 9000 mg L-1 by using reagent solution of varying concentration. The method was applied in the determination of NO2- in culture media.
Nitrite Fermentation broth Spectrophotometry

"Segmented Flow Injection Solvent Extraction Analysis"
Analyst 1988 Volume 113, Issue 12 Pages 1861-1863
Jun'ichi Toei

Abstract: A phase separator is described and illustrated that comprises two separation blocks sandwiched between two stainless-steel support blocks. A PF-1 PTFE membrane is held between the separation blocks. The separator was incorporated into a flow injection system comprising an aqueous phase and an organic phase pump and a PTFE reaction tube (10 m x 0.5 mm). As an example, the determination of Ni with furan-2,5-dione dioxime, with extraction from an aqueous phase into CHCl3, was studied. The absorbance of the organic phase was measured at 450 nm. The calibration graph was rectilinear for up to 10 ppm of Ni, and sample throughput was increased from 60 to 80 samples h-1 compared with unsegmented flow extraction. The coefficient of variation (n = 7) was 0.9%.
Nickel Spectrophotometry Sample preparation

"Continuous-flow Determination Of Sulfate With A Lead-selective Electrode"
Analyst 1988 Volume 113, Issue 12 Pages 1817-1820
Hirokazu Hara, Gy&ouml;rgy Horvai and Ern&ouml; Pungor

Abstract: The continuous-flow system (described and illustrated) was applied in the determination of SO42- in rain-water. The sample stream (1.0 mL min-1) was merged with the reagent solution (2.5 mL min-1) of 10 µM-Pb(NO3)2, 10 mM NaClO4 (I adjuster) and 10 µM-Na acetate - 1 mM acetic acid buffer in aqueous 98.6% ethanol, and the solution was mixed in a coil (2 m x 0.8 mm); SO42- was detected indirectly by using a solid-state Pb-selective electrode. The calibration graph was curvilinear from 0.01 to 1 mM SO42-. The coefficient of variation for 0.02 to 0.5 M SO42- were 5% (n = 5). There was interference from Ca, Cl and PO43-. The results were compared with those of ion chromatography; those of the proposed method were consistently greater by 27%.
Sulfate Rain Electrode Potentiometry

"Determination Of Bromide Using Flow Injection And Chemiluminescence Detection"
Analyst 1989 Volume 114, Issue 8 Pages 951-954
Issam M. A. Shakir and Azad T. Faizullah

Abstract: The aqueous sample (60 µL) was injected into 50 mM KBrO3 - 0.125 M HNO3 (3 mL min-1) before passing either through a by-pass tube or through a mini-column of Dowex HCR-W (16 to 40 mesh) to remove cations. The mixture was then merged with a stream of 5 µM-luminol - 5 mM H2O2 in a reaction coil and the chemiluminescence was measured at 417 nm. The calibration graph was rectilinear for 1 to 100 µg mL-1 of Br-, and the detection limit was 3.75 pg. The effects of various foreign ions were studied; I- interfered seriously at >1 µg mL-1. The aqueous sample (60 µL) was injected into 50 mM KBrO3 - 0.125 M HNO3 (3 mL min-1) before passing either through a by-pass tube or through a mini-column of Dowex HCR-W (16 to 40 mesh) to remove cations. The mixture was then merged with a stream of 5 µM-luminol - 5 mM H2O2 in a reaction coil and the chemiluminescence was measured at 417 nm. The calibration graph was rectilinear for 1 to 100 µg mL-1 of Br-, and the detection limit was 3.75 pg. The effects of various foreign ions were studied; I- interfered seriously at >1 µg mL-1.
Bromide Chemiluminescence

"Flow Injection With Anodic Polarographic Detection For The Determination Of Allopurinol In Pharmaceutical Formulations"
Analyst 1989 Volume 114, Issue 11 Pages 1449-1452
Tommaso R. I. Cataldi, Francesco Palmisano and Pier Giorgio Zambonin

Abstract: Powdered tablets (50 mg) were dissolved in 1 mM NaOH with sonication, and portions were injected into a stream (1 mL min-1) of 50 mM borate buffer (pH 9.2) for flow injection analysis, with use of a PAR model 174A polarographic analyzer., a dropping mercury electrode (0.5-s drop time) and detection at +150 mV vs. Ag - AgCl. The calibration graph was rectilinear for 300 µM, and the limit of detection was 1.8 µM. The within-run coefficient of variation (n = 10) was 3.1% for 28 µM. Mean recovery was 99.6% of the label claim. About 90 samples h-1 could be analyzed.
Allopurinol Pharmaceutical Electrode Polarography

"Flow Injection System For Online Potentiometric Monitoring Of Ammonia In Freshwater Streams"
Analyst 1989 Volume 114, Issue 11 Pages 1443-1447
Salvador Alegret, Juli&aacute;n Alonso, Jordi Bartrol&iacute; and Esteve Mart&iacute;nez-F&agrave;bregas

Abstract: The system involves mixing a sample stream with 1 M NaOH, passage of the mixture through a dialysis chamber to transfer NH3 via a gas diffusion chamber into 10 mM Tris (pH 7.5), and detection of NH4+ by an ion-selective electrode. The electrode construction involves in situ formation and direct casting of the sensing nonactin - PVC membrane on to an epoxy resin loaded with graphite. The calibration graph was rectilinear from 0.02 to 10 mM, and the limit of detection was ~1 µM. Over 30 samples could be analyzed in 1 h. The system involves mixing a sample stream with 1 M NaOH, passage of the mixture through a dialysis chamber to transfer NH3 via a gas diffusion chamber into 10 mM Tris (pH 7.5), and detection of NH4+ by an ion-selective electrode. The electrode construction involves in situ formation and direct casting of the sensing nonactin - PVC membrane on to an epoxy resin loaded with graphite. The calibration graph was rectilinear from 0.02 to 10 mM, and the limit of detection was ~1 µM. Over 30 samples could be analyzed in 1 h.
Ammonia Environmental Potentiometry Electrode Electrode

"Tensammetric Determination Of Phospholipids In Batch And Flow Injection Systems"
Analyst 1989 Volume 114, Issue 12 Pages 1593-1596
Hendrik Emons, Thomas Schmidt and Karel Stul&iacute;k

Abstract: Phospholipids in a flow system can be detected from the non-equilibrium differential capacitance - time response of a hanging-Hg-drop electrode at -1.8 V with an a.c. (60 Hz) amplitude of 20 mV. At this applied potential the reponse is constant at flow rates 0.5 mL min-1, but at higher flow rates increases rectilinearly with the square root of the flow rate; good reproducibility is demonstrated for successive 10.9 µg injections of phosphatidylcholine at 0.8 mL min-1 when a fresh Hg drop was formed before each injection. The rectilinear range depended on the individual phospholipids, but included the range 0.5 to 5 µg for all compounds studied. Phase transitions in the adsorbed layer as the amount of adsorbed phospholipid increases can cause reproducible discontinuities in the calibration graphs, as is shown to occur for sphingomyelin at 5 µg injected. Phospholipids in a flow system can be detected from the non-equilibrium differential capacitance - time response of a hanging-Hg-drop electrode at -1.8 V with an a.c. (60 Hz) amplitude of 20 mV. At this applied potential the reponse is constant at flow rates 0.5 mL min-1, but at higher flow rates increases rectilinearly with the square root of the flow rate; good reproducibility is demonstrated for successive 10.9 µg injections of phosphatidylcholine at 0.8 mL min-1 when a fresh Hg drop was formed before each injection. The rectilinear range depended on the individual phospholipids, but included the range 0.5 to 5 µg for all compounds studied. Phase transitions in the adsorbed layer as the amount of adsorbed phospholipid increases can cause reproducible discontinuities in the calibration graphs, as is shown to occur for sphingomyelin at 5 µg injected.
Phospholipids Sensor Electrode

"Automated Flow Injection Spectrophotometric Determination Of Para- And Meta-substituted Phenols Of Pharmaceutical Interest Based On Their Oxidative Condensation With 1-nitroso-2-naphthol"
Analyst 1990 Volume 115, Issue 3 Pages 309-313
Constantinos A. Georgiou and Michael A. Koupparis

Abstract: The reaction of para- and meta-substituted phenols with 1-nitroso-2-naphthol in the presence of either Ce(IV) or Pb(IV) as an oxidant has been used to develop a fast automated flow injection (Fl) method. A stopped-flow kinetic study of the reaction revealed the optimum conditions for the proposed Fl method. Acetaminophen, amoxicillin, cefadroxil, isoxsuprine, nylidrin, propylparaben, tyrosine and metaraminol can be determined in the range 1 x 10^-4-8 x 10^-4 M, with relative standard deviations of less than 2%, and a measurement throughput of 40 measurements h-1. The method was evaluated by performing interference studies of common excipients and assaying commercial formulations of acetaminophen and isoxsuprine. The results were in good agreement with those obtained by acceptable spectrophotometric or high performance liquid chromatographic methods (mean difference 2.1%). The high sample throughput of the Fl method was exploited by performing a content uniformity test of isoxsuprine tablets. Aqueous solution of tablet or liquid formulations were passed through a 200 µL sample loop of a flow injection analyzer. and mixed with 2 mM 1-nitroso-2-naphthol in 10% DMSO - 1% polysorbate 80, the mixture was treated with 6 mM Ce(IV) in 1 M H2SO4 or 10 mM Pb(IV) in 2 M HCl and absorbance was measured at 540 or 510 nm for Ce(IV) or Pb(IV) oxidants, respectively. Calibration graphs of paracetamol, amoxycillin, cefadroxil, isoxsuprine, buphenine, propyl hydroxybenzoate, tyrosine and metaraminol were rectilinear from 10 to 80 mM in the test solution Recoveries were good and the coefficient of variation were 2%. Interference from common excipients was not significant and results agreed well with those by spectrophotometry or HPLC.
Acetaminophen Amoxycillin Cefadroxil Isoxsuprine Buphenine Tyrosine Metaraminol Nylidrin Propylparaben Pharmaceutical HPLC Spectrophotometry

"Determination Of Diphenhydramine Hydrochloride By Flow Injection With Bromophenol Blue And Turbidimetric Measurement"
Analyst 1990 Volume 115, Issue 6 Pages 855-858
J. Martinez Calatayud, A. Sanchez Sampedro and S. Navasquillo Sarrion

Abstract: Powdered tablets were mixed with water, the mixture was filtered and diluted to volume A 210 µL aliquot of the solution was injected into a carrier - reagent stream (2.69 mL min-1) of 1.19 mM bromophenol blue (pH adjusted to 1.2 with HCl). The turbidity was measured spectrophotometrically at 650 nm. The calibration graph was rectilinear for 50 to 230 ppm of diphenhydramine hydrochloride. The coefficient of variation (n = 20) was 0.3% and the injection rate was 51 samples h-1. The study of a number of diphenhydramine-dye systems was carried out in order to determine the most suitable precipitate for the turbidimetric determination of diphenhydramine using flow injection (FI). The reagent selected was Bromophenol Blue. The chemical and FI variables were optimized. The calibration graph was linear over the concentration range 50-230 p.p.m. of diphenhydramine hydrochloride. A number of interfering substances were also investigated.
Diphenhydramine Pharmaceutical Spectrophotometry Turbidimetry

"Flow Apparatus For Monitoring Dissolution Rate Curves Using Ion-exchange Resins. 1. Phosphite Dissolution Rate Curve"
Analyst 1990 Volume 115, Issue 6 Pages 765-769
N. P. Evmiridis and E. D. Economou

Abstract: The system comprised a carrier stream of water or aqueous acidic solution, flowing through a cell containing a glass pH micro-electrode, and a syringe containing Dowex HGR-W2 ion-exchange resin, for exchange of metal ions for H+ for subsequent injection into the carrier stream. Two injections were made per sample, one before and one after ion exchange. The calibration graph was rectilinear for pH 1 to 5. The method was reasonably accurate, reproducible, rapid and simple. The method can be applied to determine a wide range of metal ion concentration. and can be made selective for one ion in the presence of others by pre-complexation. The method is applicable to study dissolution rate curves, and was applied to the dissolution of CaCO3 in H3PO4 as an example.
Calcium carbonate Inorganic compound

"Rapid Differential Flow Injection Of Phosphorus Compounds In Wastewater By Sequential Spectrophotometry And Inductively Coupled Plasma Atomic Emission Spectrometry Using A Vacuum Ultraviolet Emission Line"
Analyst 1990 Volume 115, Issue 8 Pages 1055-1058
Jamshid L. Manzoori, Akira Miyazaki and Hiroaki Tao

Abstract: Sample was injected into 0.5 M HNO3 as carrier stream, which was mixed with a reagent stream comprising (NH4)6Mo7O24 and NH4VO3 in HNO3. Phosphate was determined as molybdovanadophosphate by spectrophotometry at 470 nm, and the eluate was fed to an ICP-AES system for determination of total P at 177.499 nm. The calibration graphs were rectilinear for 200 µg mL-1 of P for both detection methods, and the limits of detection were 0.8 and 0.5 µg mL-1, respectively. Of several common ions examined, only Cr interfered in the spectrophotometric method. The coefficient of variation was 2.0% for 10 µg mL-1 of P (n = 11). Eighty samples per hour could be analyzed. The method was applied to treated sewage and metal-plating waste water.
Phosphorus Waste Spectrophotometry

"Flow Injection Of Lithium Ion Using Chromogenic 14-crown-4 Derivatives As Extraction-spectrophotometric Reagents"
Analyst 1990 Volume 115, Issue 9 Pages 1251-1255
Keiichi Kimura, Shin-ichi Iketani, Hidefumi Sakamoto and Toshiyuki Shono

Abstract: A system for flow injection of Li+ has been designed, with use of proton-dissociable chromogenic 14-crown-4 derivatives as the extraction-spectrophotometric reagents, and the analytical conditions have been optimized. This flow injection system showed high selectivity for Li+ reflecting the cation-complexing property of the chromogenic crown ethers. The determination of Li+ in the clinical range in blood under a high Na+ background of 130-160 mM was feasible, with a small sample size (50 µL) and high sampling rate (more than 100 injections per hour), with this method. The proposed extraction-spectrophotometric flow injection system was, therefore, found to be promising for the efficient determination of Li+ in biological samples, such as blood sera, with a high Na+ background. Conditions for the use of six 14-crown-4 derivatives were determined. The best results were obtained with 14-crown-4-dinitrophenol at pH 9.5 for a carrier stream of H3BO3 - KOH and a solvent stream of CHCl3, both at 0.75 mL min-1. Detection was at 410 nm and the coil length was 1 m. The samples e.g., blood sera, and the crown ether were injected into the aqueous and organic streams respectively and the Li+ was extracted in the coil. The response was rectilinear up to 2 mM with a limit of detection of 0.1 µM. High backgrounds caused by the presence of Na+ were compensated for, by preparing calibration standards containing 145 mM Na+.
Lithium Blood Serum Spectrophotometry Sample preparation

"Determination Of L-ascorbic Acid In Fruit And Vegetable Juices By Flow Injection With Immobilised Ascorbate Oxidase"
Analyst 1990 Volume 115, Issue 10 Pages 1297-1299
Gillian M. Greenway and Peter Ongomo

Abstract: Ascorbate oxidase was immobilized on cyanogen bromide activated-Sepharose 4B and incorporated in a flow injection system with amperometric detection at a glassy carbon electrode at +0.6 V. On passage through the immobilized ascorbate oxidase a fraction of the L-ascorbic acid was converted into dehydroascorbic acid and the decrease in signal was measured. This could be directly related to the amount of L-ascorbic acid present. The calibration graph was linear over the range 0-400 ng mL-1 with a correlation coefficient of 0.9994. The detection limit (2s) in phosphate buffer (0.08 M, pH 5.5) was 4.0 ng mL-1. The relative standard deviation for a 200 ng mL-1 standard was 1.0% (n = 10) and the sampling throughput was 30 samples h-1. The method was used for the simple and rapid determination of L-ascorbic acid in fruit and vegetable juice.
l-Ascorbic acid Fruit Vegetable Amperometry Electrode

"Automated Flow Injection Measurement Of Photographic Dyes In Gelatin At Elevated Temperatures"
Analyst 1990 Volume 115, Issue 11 Pages 1407-1410
Richard H. Taylor, Gregory D. Clark, Jaromir Ruzicka and Gary D. Christian

Abstract: Photographic dyes in a gelatin matrix were determined by automated flow injection analysis, by using the split zone - gradient chamber dilution technique (Clark et al., Anal. Chem., 1989, 61, 1773), DMSO as carrier solvent and direct spectrophotometric detection (at 553 nm for a magenta dye and 459 nm for a yellow dye). The matrix was kept liquid by placing the apparatus in an incubator oven at 41°C to 44°C. With dilution times of 60 and 30 s for the magenta and yellow dyes, respectively, calibration graphs were rectilinear for 60 and 100 g l-1, respectively. The coefficient of variation was 2% for dilutions of 2000-fold. Results agreed to within 5% with those of a manual method.
Dyes, photographic Organic compound Spectrophotometry

"Electrocatalytic Detection Of Streptomycin And Related Antibiotics At Ruthenium Dioxide Modified Graphite--epoxy Composite Electrodes"
Analyst 1990 Volume 115, Issue 11 Pages 1447-1450
Donal Leech, Joseph Wang and Malcolm R. Smyth

Abstract: The application of ruthenium dioxide (RuO2) modified electrodes to the electrocatalytic detection of the saccharide-related antibiotics streptomycin, novobiocin and neomycin, at low fixed potentials, was investigated. The RuO2-modified graphite - epoxy composite electrodes give extremely stable and reproducible catalytic oxidation currents for these antibiotics at potentials as low as +0.2 V (versus Ag - AgCl). Rapid quantification at the micromolar level is therefore possible. Standard calibration graphs for streptomycin and neomycin yielded slopes of 4.43 and 0.08 nA µM-1 over the linear ranges of 1.5 x 10^-6 - 2.5 x 10^-4 and 1 x 10^-5 - 2 x 10^-3 M, respectively. Owing to its catalytic oxidation by the Ru(III) - Ru(IV) couple, rather than the Ru(IV) - Ru(VI) transition (which catalyses the oxidation of streptomycin and neomycin), novobiocin could be detected at a lower (+0.2 V) potential, with a sensitivity of 1.31 nA µM-1. Detection limits of 1.5, 6.0 and 10 µM were obtained for streptomycin, novobiocin and neomycin, respectively. These catalytic surfaces can be renewed (by polishing), with a surface-to-surface reproducibility of 6.5% for the detection of 5 x 10^-5 M streptomycin. The analytical application of RuO2-modified carbon paste electrodes to the analysis of these antibiotics by flow injection was investigated, with a view to liquid chromatographic separation with electrochemical detection applications.
Streptomycin Novobiocin Neomycin B Electrode Electrode Electrode

"Continuous-flow Chemiluminescence Determination Of Some Corticosteroids"
Analyst 1990 Volume 115, Issue 12 Pages 1553-1557
Ioanna I. Koukli and Antony C. Calokerinos

Abstract: Powdered tablets (200 mg), injection solution (2 ml) or creams (1 g) were dissolved in and diluted with 0.1 M H2SO4 for dexamethasone (I) and hydrocortisone (II) or 0.1 M H2SO4 containing 1% acetone for prednisolone (III), methylprednisolone (IV), dexamethasone (V) or betamethasone (VI). Portions of solution were analyzed in an air-segmented continuous-flow manifold by mixing the sample stream (2 mL min-1) with 0.5 mM ammonium Ce(IV) sulfate in 0.1 M H2SO4 and with aqueous 0.01 M Na2SO3 (both at 0.8 mL min-1) and the resulting chemiluminescence was measured. Calibration graphs were rectilinear from 0.1 to 1 µg mL-1 of I, II, III and IV, and from 0.5 to 5 µg mL-1 of V and VI with detection limits of 0.02 to 0.3 µg mL-1. The coefficient of variation were 1.3 to 4.9% and 1.6 to 6.2% for I and II, respectively. There was no interference from excipients. The sampling rate was 40 h-1. Results agreed well with those of an official method.
Corticosteroids Pharmaceutical Chemiluminescence

"Use Of Photochemical Reactions In Flow Injection: Determination Of Oxalate In Urine"
Analyst 1990 Volume 115, Issue 12 Pages 1549-1552
Luis E. Leon, Angel R&iacute;os, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The use of photochemical reactions in flow injection (FI) is reported. The irradiation of an FI reactor with a suitable source facilitates the development of the iron(III)-oxalate reaction, allowing the amperometric determination of the anion in the range 1.0-13.0 µg mL-1, with a relative standard deviation of 1.1% and a sampling frequency of 40 h-1. The proposed method was applied successfully to the determination of oxalate in urine samples. Urine (5 ml) was adjusted to pH 5.0 to 5.2 with acetic acid or aqueous NH3 solution, shaken with 0.7 M CaCl2 (2 ml) and kept at 4°C for 2 h, and the ppt. was collected, washed with saturated CaCl2 solution and dissolved in 0.1 M H2SO4. The solution was injected into a carrier stream of 0.1 M H2SO4 and mixed with a reagent stream of 0.1 M H2SO4 containing Fe(III) (both at 0.5 mL min-1) at 40°C in a reactor (1 m x 0.8 mm). The reaction mixture was irradiated before detection at a vitreous C electrode with an auxilliary electrode of the same material vs. Ag - AgCl. The calibration graph was rectilinear from 1 to 13 µg mL-1 of oxalate (I) and the detection limit was 0.64 µg mL-1. Recoveries were 93 to 98% and the coefficient of variation (n = 11) was 2.6 and 1.1% for 1.3 and 9.4 µg mL-1 of I. Citrate and tartrate interfered seriously; malate, picrate, salicylate, and barbituric and uric acids did not.
Oxalate Urine Amperometry Electrode

"Flow Injection Determination Of Thiamine Based On Its Oxidation To Thiochrome By Mercury(II)"
Analyst 1990 Volume 115, Issue 2 Pages 217-220
Carmen Martinez-Lozano, Tom&aacute;s P&eacute;rez-Ruiz, Virginia Tom&aacute;s and Concepci&oacute;n Abell&aacute;n

Abstract: A 175 µL sample was mixed with 5 mM Hg(II) solution at pH 4 before combining with 0.2 M phosphate buffer (pH 12.5), each flowing at 0.87 mL min-1, in a thermostatted PTFE reaction coil (300 cm x 0.5 mm). Thiochrome fluorescence was measured at 465 nm (excitation at 370 nm). Calibration graphs were rectilinear from 0.2 to 7 µM. The detection limit was 34 nM, and the coefficient of variation for 4.5 µM was 0.2% (n = 11). Sample throughput was 22 samples h-1. The method was successfully applied to multivitamin preparations.
Thiamine Fluorescence

"Automated Spectrophotometric Determination Of Titanium(IV) In Water And Brines By Flow Injection Based On Its Reaction With Hydrogen Peroxide"
Analyst 1990 Volume 115, Issue 3 Pages 315-318
M. Mu&ntilde;oz, J. Alonso, J. Bartrol&iacute; and M. Valiente

Abstract: A flow injection system is described (with diagram). Water (13 µL) in H2SO4 was injected into a 0.7 M H2SO4 carrier stream (2.2 mL min-1) and diluted in a coil (50 cm x 0.7 mm) with water (2.2 mL min-1). The stream was then mixed in a coil (1 m x 0.7 mm) with 3% (w/v) H2O2 in 0.7 M H2SO4 (2.2 mL min-1) and the absorbance was measured at 410 nm. Calibration graphs of Ti in the sample were rectilinear up to 1000 ppm at a sampling rate of 240 hmin1. Detection limit was 9 ppm, and the coefficient of variation was 0.6%. Interference from Fe, V and Mo can be avoided by selective precipitation during sample pre-treatment. A system is also described for the determination of low Ti concentration. in brine using 3.3 M Mg(NO3)2 - 1 M HCl as carrier; the calibration graph was rectilinear up to 30 ppm, coefficient of variation were 0.7% and the detection limit was 0.3 ppm.
Titanium(IV) Water Environmental Spectrophotometry

"Determination Of Zinc In Plants By Flow Injection Spectrophotometry With Ion-exchange Separation"
Analyst 1990 Volume 115, Issue 6 Pages 779-782
Jos&eacute; Roberto Ferreira, Elias Ayres Guidetti Zagatto, Marco Aur&eacute;lio Zezzi Arruda and Sandra Maria Boscolo Brienza

Abstract: Ashed samples are dissolved in 2 M HCl and injected into a carrier stream of 2 M NaCl - 10 mM HCl, which then flows through a column of Dowex 1-X8 for retention of chlorozinc complexes. These are eluted with 0.1 M NaOH, and after addition of 0.1% of zincon in 20 mM NaOH, detection is at 620 and 800 nm. The calibration graph covered the range 2 mg l-1. The coefficient of variation was 0.4% at 0.56 mg L-1 of Zn. Phosphate does not interfere at 200 mg l-1; Cd interferes but is usually present in low concentration. Up to 45 samples h-1 can be analyzed.
Zinc Plant Ion exchange

"Flow Injection Spectrophotometric Determination Of The Biuret Content In Urea Fertilizers"
Analyst 1990 Volume 115, Issue 3 Pages 319-321
Joanna Szpunar-Lobiska, Marek Trojanowicz and Liliana Ilcheva

Abstract: Flow injection systems are described (with diagrams). Fertilizer solution (50 µL) was injected into water carrier stream (0.7 mL min-1) and the stream was passed through a cation-exchange column (2 cm x 3 mm) packed with Dowex 50-X8 (100 to 200 mesh). The solution was mixed with 0.1 M sodium tartrate in 0.25 M NaOH (2.1 mL min-1) and 0.01 M CuSO4 in acidified water (1.4 mL min-1) and the absorbance was measured at 550 nm. Calibration graphs of biuret in the sample were rectilinear up to 5.0 mg mL-1; coefficient of variation were 1.2 to 2.5%. Recoveries were 98.9 to 104.5%. The only interferent, NH3, was removed with the ion-exchange column. Results agreed well with those by conventional methods.
Biuret Commercial product Ion exchange Spectrophotometry

"Gel-phase Absorptiometry Of Phosphate With Molybdate And Malachite Green And Its Application To Flow Analysis"
Analyst 1990 Volume 115, Issue 6 Pages 843-848
Kazuhisa Yoshimura, Sawako Nawata and Genichiro Kura

Abstract: Phosphate in water was determined by formation of an ion-association complex with ammonium molybdate - C. I. Basic Green 4, then either, (i) adsorption onto Sephadex LH-20 beads which were then packed into a 5-mm cell for absorbance measurement at 627 and 750 nm vs. air; the difference between the absorbance at the two wavelengths was proportional to the PO43- concentration, or (ii) concentration online onto the gel in a flow-through cell for measurement of the absorbance at 627 nm. For procedure (i) calibration graphs were rectilinear for up 10 µg L-1 of PO43-; the detection limit was 0.6 µg l-1. For procedure (ii) calibration graphs are plotted for up to 3 µg l-1; the rectilinear range varied with sample volume. Recoveries were 98 to 105%; detection limit (flow injection procedure) was 75 ng l-1. The method was applied to softened-, rain-, ground-, river and seawater.
Phosphate River Ground Sea Rain Spectrophotometry

"Determination Of Orthophosphate In Waters And Soils Using A Flow Analyser"
Analyst 1990 Volume 115, Issue 1 Pages 65-67
David J. Malcolme-Lawes and Koon Hung Wong

Abstract: Samples (0.3 ml) were injected into a high performance continuous-flow analyzer. (carrier 1.5% of NaCl in 0.12 M HNO3) downstream of the manifold where the reagents NH4MoO4, K - Sb tartrate (catalyst) and L-ascorbic acid were pre-mixed. Absorbance of the heteropolymolybdenum blue complex was measured at 670 nm. Interferences from ions commonly found in potable waters were small. The calibration graph was rectilinear for 100 ppm, and the detection limit was 4.8 ppb of P. Sample throughput was >120 h-1 at 4 ppm. The method was applied to soil samples after extraction with NaHCO3 solution
Phosphate Water Environmental Spectrophotometry Sample preparation

"Determination Of Oxonium Ion In Strongly Ionisable Inorganic Acids And Determination Of Substituted Acetic Acids Using Flow Injection And Chemiluminescence Detection"
Analyst 1990 Volume 115, Issue 1 Pages 69-72
Issam M. A. Shakir and Azad T. Faizullah

Abstract: Samples (60 µL) of 200 mM of H2SO4, HCl, HClO4, HNO3 or H3PO4 were injected first into a water carrier stream (2 mL min-1) before combining with a BrO3- - Br- stream and entering the reaction coil with 100 mM H2O2 and 0.5 mM luminol in Na2CO3 solution The H3O+ concentration. was determined indirectly from the chemiluminescence peak intensity. The log. - log. calibration graphs were rectilinear. The method was applicable to chloroacetic and trichloro- and trifluori-acetic acids. Detection limits ranged from 4 mM for formic acid to 20 mM for H3PO4 and chloroacetic acid. The coefficient of variation were 1% (n = 4) and sample throughput was 90 h-1.
Oxonium Chloroacetic acid Trichloroacetic acid Trifluoroacetic acid Formic acid Chemiluminescence

"Novel Single-standard Calibration And Dilution Method Performed By The Sequential Injection Technique"
Analyst 1992 Volume 117, Issue 12 Pages 1839-1844
Alan Baron, Miguel Guzman, Jaromir Ruzicka and Gary D. Christian

Abstract: The sequential injection technique is used to generate rapidly a series of exactly diluted aliquots from a single standard. It can be used to produce a calibration set (which is able to detect a non-linear response) or to dilute samples to the appropriate analytical concentration. range. Its application to analysis of glucose using glucose oxidase by both sensor-injection analysis and multi-zone stopped-flow analysis is described. A novel single standard calibration and dilution method utilizing the sequential injection analysis (SIA) technique is described. The SIA manifold employs a dilution conduit for storing a concentration. gradient of an injected analyte, which provides for a variable calibration and dilution scheme suitable for both single and multizone analyzes by taking selected aliquots from the gradient. This paper describes the principles of the method, the experimental characterization of the SIA manifold with bromothymol blue dye using a spectrophotometric detector and the application of the method to glucose determination using glucose oxidase by sensor injection analysis and by multizone stopped-flow anal.
Glucose Enzyme, glucose oxidase Sensor

"Permeation Tubes For Calibration In Flow Injection Analysis"
Analyst 1993 Volume 118, Issue 9 Pages 1227-1231
Stuart J. Chalk, Julian F. Tyson and Don C. Olson

Abstract: The use of a permeation tube for the production of liquid stream calibration standards in the flow injection determination of NH3 was investigated. The manifold (diagram and full description given) was constructed from 0.8-mm PTFE tubing, polyethylene ethyl ketone nuts and ferrules and PTFE unions. A six-port rotary inspection valve with 0.8-mm PTFE tubing connections was used for sample injection and the manifold was interfaced to the spectrometer using a 1-cm pathlength flow cell. An ammonia controlled-release Dynacal permeation tube with an active length of 5 cm was inserted into a 10 cm glass column; the carrier stream and permeation tube streams were 0.01 M HNO3. By varying the flow rate from 0.5 to 4 ml/min, calibration standards over the range 1.5-0.18 ppm could be obtained. The relationship between concentration. of the resulting solution and the reciprocal of the flow rate was linear. The manifold was applied to the determination of NH3 in pond water.
Ammonia Pond Spectrophotometry

"Simultaneous Kinetic Spectrophotometric Determination Of 2-furfuraldehyde And 5-hydroxymethyl-2-furfuraldehyde By Application Of A Modified Winklers Method And Partial Least-squares Calibration"
Analyst 1995 Volume 120, Issue 10 Pages 2567-2571
Isabel Dur&aacute;n Mer&aacute;s, Anunciaci&oacute;n Espinosa Mansilla and Francisco Salinas L&oacute;pez

Abstract: A method is described for the simultaneous determination of 2-furfuraldehyde and 5-hydroxymethyl-2-furfuraldehyde; based On their reaction by a modified Winkler's method. A comparative study of the results found using the kinetic curves registered at 550 and 585 nm, as analytical signals, has been performed, The data set of the kinetic curves at 550 nm was selected as the analytical signal, Partial least squares (calibrating for a single chemical constituent at a time: PLS-1) multivariate calibration was then applied for the determination, The proposed method was satisfactorily applied to the analysis of wines, spirits, fruit juices and honey. (31 references)
2-Furaldehyde 5-Hydroxymethyl-2-furaldehyde Beverage Wine Fruit Food Spectrophotometry Spectroscopy

"Flow Manifold For Automated Online Dilution Of Standards For Flame Atomic Absorption Spectrometry And Its Use In A Null Measurement Method"
J. Anal. At. Spectrom. 1987 Volume 2, Issue 2 Pages 217-220
Stephen R. Bysouth and Julian F. Tyson

Abstract: The cited manifold is based upon a fixed-speed pump, together with a computer-controlled switching valve and pump, so that automatic dilution is combined with maintenance of a constant-volume flow to the nebulizer for flame AAS. The computer is also used for data handling and processing. Operation in flow injection mode with manual control of the switching valve and pump has been tested with no great success. Calibration can be in the conventional manner or by a null measurement method in which a stock standard solution is diluted by a known factor to match precisely the absorbance of the sample; Cr (null measurement mode) and Mg (flow injection mode) are used as test analytes. In the null measurement method, peristaltic-pump flow pulsation gives rise to problems with accurate flow-rate measurement which remain to be solved successfully.
Chromium Magnesium Spectrophotometry

"Network Flow Injection Manifolds For Sample Dilution And Calibration In Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1988 Volume 3, Issue 1 Pages 211-215
Julian F. Tyson and Stephen R. Bysouth

Abstract: An asymmetrical two-branch network permitting measurement at the maxima of and the minimum between two overlapping peaks generated from a single injection and a three-branch network permitting measurement at three such maxima and the two minima between them are described. Their performance in the dilution of off-range samples and extension of the calibration range is compared. The two-branch network was the better, being the less sensitive to flow-rate fluctuations.
Magnesium Spectrophotometry

"Liquid Chromatography With An Inductively Coupled Plasma Mass-spectrometric Detector For Simultaneous Determination Of Gold Drug Metabolites And Related Metals In Human Blood"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 8 Pages 767-771
Susan G. Matz, R. C. Elder and Katherine Tepperman

Abstract: Blood plasma or serum (0.5 ml) was digested with 2.5 mL of aqueous 40% HNO3 with heating for 30 s at 700 W. The cooled digest was analyzed by ICP-MS in conjunction with a flow injection system. The mobile phase comprised water, aqueous 5% HNO3, 50 mM NH4 acetate buffer (pH 5.5) or 50 mM Tris buffer (pH 6.5). Matrix effects were significant. Detection limits were 0.2 to 0.7 ppb of Au, Zn and Cu, and calibration graphs were rectilinear up to 1000 ppb. The digests were also determined by ICP-MS after separation by HPLC on a column (15 cm x 4.6 mm) of Alltech WAX 300 anion exchanger with 20 to 200 mM Tris buffer (pH 6.5) as mobile phase or on a column (30 cm x 7.5 mm) of Bio-Sil TSK 250, with 25 mM Tris buffer (pH 7.7) as mobile phase. The HPLC - ICP-MS system was applied in the simultaneous determination of sixteen elements.
Copper Gold Zinc Plasma Human Serum Human Mass spectrometry Sample preparation

"Flow Injection Inductively Coupled Plasma Mass Spectrometry For The Determination Of Platinum In Airborne Particulate Matter"
J. Anal. At. Spectrom. 1990 Volume 5, Issue 1 Pages 75-80
Hitoshi Mukai, Yoshinari Ambe and Masatoshi Morita

Abstract: Standard solution of Pt in 0.6 M HCl and samples of particulate airborne matter (prep. described) were introduced into a flow injection system (described) incorporating a cation-exchange column (16 cm x 8 mm) of Dowex 50W-X8 (50 to 80 mesh) which was pre-washed with 3 M HCl and stabilized with 0.6 M HCl. This system was used online for trapping major matrix elements, which cause suppression of the Pt signal at m/e = 195, and Hf (which interferes spectrally) from 0.6 M HCl medium. The eluate from the column was introduced into the ICP-MS for the determination of Pt. The calibration graph was rectilinear up to 40 µg L-1 of Pt, and the coefficient of variation (n = 5) for 2 µg L-1 of Pt was ~5%. The detection limit was ~0.1 µg L-1 of Pt in solution or 5 ng g-1 in airborne particulate matter. The method was applied to the determination of Pt in samples such as vehicle exhaust particulates and roadside dust.
Platinum Exhaust Particulates Road Mass spectrometry Ion exchange

"Online Gradient Calibration For Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 2 Pages 335-338
Timothy K. Starn and Gary M. Hieftje

Abstract: A microprocessor-controlled, automated, online method for generating calibration standards is described. Math. gradients, programmed with a high performance liquid chromatography pump module, mix stock and dilute solutions to form desired concentrations Online produced gradient calibrations are demonstrated to be comparable to those made with individual solution standards Advantages of the technique are the convenience and savings involved in maintaining a limited selection of stock solutions and the ease of performing standard additions calibrations. A possible drawback is a slight, but noticeable, time lag between successive gradient steps.
Spectrophotometry

"Online Dilution System For Extending The Calibration Range Of Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 8 Pages 1291-1294
Ignacio L&oacute;pez Garc&iacute;a, Jes&uacute;s Arroyo Cortez and Manuel Hern&aacute;ndez C&oacute;rdoba

Abstract: A flow injection manifold is described and illustrated in which the sample is transported by the carrier to a variable-volume mixing chamber. A plug of air displaces the diluted solution from the chamber and facilitates mixing before nebulization. The system was applied to the determination of standard solution of Cu and Ca. With the smallest injection volume (26 µL) and the max. dilution tested (10 ml) the calibration graphs were rectilinear from 20 to 3000 µg mL-1 of Cu and 5 to 1800 µg mL-1 of Ca. The respective detection limits were 0.2 and 0.5 µg mL-1.
Copper Calcium Spectrophotometry

"Polymer-bound Tetrahydroborate For Arsine Generation In A Flow Injection System"
Anal. Chem. 1989 Volume 61, Issue 18 Pages 2079-2082
Solomon Tesfalidet and Knut Irgum

Abstract: Generation of arsine for subsequent AAS determination was carried out in a flow system using a column (10 cm x 6 mm) of Amberlyst A-26 (20 to 50 mesh) in the tetraborate form as a polymer-supported reducing agent. The analysis cycle comprised regeneration, washing and injection of HCl-acidified sample, and could be repeated every 4 min. The detection limit for As(III) was 1.5 µg L-1 (40 µL sample) and the calibration graph was rectilinear up to 100 µg l-1. Nickel, Co, Cu and Fe ions caused 10% signal degradation when present at concentration. of 2500 to 5000 mg L-1 when L-cystine was added as masking agent. The column could be used for at least 3 months without performance degradation.
Arsenic Spectrophotometry

"Flow System For Starch Determination Based On Consecutive Enzyme Steps And Amperometric Detection At A Chemically Modified Electrode"
Anal. Chem. 1990 Volume 62, Issue 3 Pages 263-268
J. Emneus and L. Gorton

Abstract: A flow injection system is described for the determination of the total glucose content of starch. The system comprises three reactors, in each the required enzyme is immobilized on glutaraldehyde-activated, aminopropyl-silanized controlled-pore glass (CPG) of specific diameter and pore size, these being, respectively, (i) Termamyl 120L (Novo Industri, Denmark), used at 60°C on CPG (75 to 125 µ diameter), (ii) amyloglucosidase, from Aspergillus niger, on CPG (125 to 180 µm) and (iii) porcine mutarotase co-immobilized with glucose oxidase, on CPG (37 to 74 µm). The H2O2 released in (iii) is detected at a graphite electrode with a catalytic layer of Au - Pd (3:2), operated at +0.6 V vs. Ag - AgCl. The carrier flow (0.5 mL min-1) is 0.1 M acetate buffer of pH 5.0 for (i) and (ii) adjusted to pH 7.0 for (iii) by addition of 0.2 M phosphate (pH 7.6). Calibration graphs are rectilinear from 10 µM- to 0.6 mM of glucose with an injection volume of 160 µL and 15 samples h-1 throughput.
Glucose Organic compound Amperometry Electrode

"Fiber-optic Glucose Sensor With Electrochemical Generation Of Indicator Reagent"
Anal. Chem. 1990 Volume 62, Issue 7 Pages 755-759
Hari Gunasingham, Chin Huat Tan, and Jimmy K. L. Seow

Abstract: The prep. is described of a reversible enzyme-based optical-fiber sensor, involving the electrochemical regeneration of the optically active redox mediator tetrathiafulvalene as the indicator. The performance of the sensor as a thin-layer cell configuration was evaluated in flow injection and steady-state analyzes giving a rectilinear calibration graph for ~12 and 3 mM, respectively, and a detection limit of 0.2 mM glucose. Potential interfering species such as O and organic species had no significant effect on detector response. The response was compared with an amperometric detector.
Glucose Amperometry Sensor

"Electrochemical Platinization Of Reticulated Vitreous-carbon Electrodes To Increase Biosensor Response"
Anal. Chem. 1990 Volume 62, Issue 11 Pages 1106-1110
George H. Heider, Sylvia V. Sasso, Keming Huang, Alexander M. Yacynych, and Henry J. Wieck

Abstract: A method is given for the partial plating of a reticulated vitreous-carbon electrode (2 cm x 3 mm diameter) with Pt. The electrode was then coated with glucose oxidase with use of the carbodi-imide immobilization technique. The resulting electrode was used for the determination of glucose in serum by flow injection analysis (max. sampling rate 118 h-1). Samples (5 or 100 µL) were injected into the carrier stream (0.1 M phosphate buffer of pH 7.4; 2 mL min-1). The H2O2 formed in the enzymatic reaction was detected amperometrically at +0.6 V vs. the SCE. Calibration graphs were rectilinear for up to 50 and 10 mM glucose, respectively, for the two sample sizes, with corresponding detection limits of 0.25 and 0.05 mM. These responses make the electrode applicable in the clinical range (3.5 to 6.5 mM).
Glucose Blood Serum Electrode Sensor

"Chemiluminescent Method For Continuous Monitoring Of Nitrous Acid In Ambient Air"
Anal. Chem. 1990 Volume 62, Issue 19 Pages 2084-2087
Yukio Kanda and Masafumi Taira

Abstract: Air is drawn through a Teflon filter at 2 l min-1, mixed with 5 mM Na2CO3 (0.2 mL min-1) and passed through a ten-turn stripping coil (illustrated). The Na2CO3 scrubbing solution is reduced with 0.1 M ascorbic acid - 0.05 M H2SO4 and the mixture is passed into a gas - liquid separating coil consisting of microporous PTFE tubing inside a silicone tubing sheath (illustrated). The NO evolved diffuses through the microporous separating coil and is swept in a stream of NO-free air into a chemiluminescent NOx analyzer.. Interference by NO2 and peroxyacetyl nitrate are corrected for with use of a dual channel measurement system (diagram given). The calibration graph was rectilinear for 0.21 to 8.5 ppb of HNO2 and the limit of detection was 0.11 ppb. The method has been applied in the determination of ambient HNO2 and HNO2 produced by synchrotron radiation in a high-energy electron storage ring.
Nitrous acid Environmental Chemiluminescence

"Indirect Inductively Coupled Plasma Atomic Emission Determination Of Fluoride In Water Samples By Flow Injection Solvent Extraction"
Anal. Chem. 1990 Volume 62, Issue 22 Pages 2457-2460
Jamshid L. Manzoori and Akira Miyazaki

Abstract: An indirect determination of fluoride in water by inductively coupled plasma atomic emission spectrometry combined with flow injection coupled with solvent extraction is reported in this paper. A manifold for rapid determination of fluoride has been designed that uses a single coil for complex formation and extraction. The method involves the formation of lanthanum/alizarin complexone/fluoride complex and its extraction into hexanol containing N,N-diethylaniline. The concentration of fluoride is determined indirectly by introduction of the organic layer into the plasma and measurement of the emission intensity of the La II 333.75-nm line. The optimum experimental conditions for the determination are described. A coiled groove phase separator fitted with a grid and PTFE porous membrane was used in this work. The sampling rate was 36 samples per hour and the calibration graphs were linear from 0.03 to 1.3 µg/mL. The relative standard deviation found was 2.16% for 200 µL of 1µg/mL of fluoride. The method is selective and has been applied satisfactorily to the determination of fluoride in water samples.
Fluoride Water Spectrophotometry Sample preparation

"Expansion Of Dynamic Working Range And Correction For Interferences In Flame Atomic Absorption Spectrometry Using Flow Injection Gradient Ratio Calibration With A Single Standard"
Anal. Chem. 1991 Volume 63, Issue 2 Pages 151-159
Michael Sperling, Zhaolun Fang, and Bernhard Welz

Abstract: An algorithm, CLAIR, based on gradient ratio evaluation was derived (details given). The algorithm is capable of utilizing the total transformation in the transient signal for calibration and interference correction. With use of the algorithm, the entire working range of the spectrometer is calibrated by use of only one reference solution, thus avoiding problems due to curvature or instrumental drift. The algorithm also corrects for multiplicative interference effects. Results are presented for flow injection flame AAS of Ca in the presence of PO43-.
Calcium Spectrophotometry

"Double-injection Flow Injection Analysis Using Multivariate Calibration For Multi-component Analysis"
Anal. Chem. 1991 Volume 63, Issue 8 Pages 775-781
David A. Whitman, Mary Beth Seasholtz, Gary D. Christian, Jarda Ruzicka, and Bruce R. Kowalski

Abstract: The flow injection system described is based on the zone penetration technique (cf. Ruzicka and Hansen, Flow injection Analysis, 2nd edition Wiley and Sons, 1988, 63 and 258) and involves simultaneous injection of sample and reagent in a single flow line. Double injection was performed by use of a simple 8-port value wherein the sample occupied the leading injection loop and the reagent the second one. The analytes yielded overlapping but different concentration. profiles along the time axis and these were analyzed by multivariate calibration methods based on partial least-squares or principal component regression. Application of the method is illustrated by the simultaneous determination of Fe and Ni in a model plating bath solution Nickel was determined via its green aquo species whilst Fe was determined as its Fe(III)-SCN- complex. The proposed method uses only one-eight of the sample and reagent required for the single injection procedure described previously (cf. Anal. Chim. Acta, 1988, 214, 197).
Iron Nickel Spectrophotometry

"Non-linear Calibration Of Ion-selective Electrode Arrays For Flow Injection Analysis"
Anal. Chem. 1992 Volume 64, Issue 15 Pages 1721-1728
Robert J. Forster and Dermot Diamond

Abstract: An ion-selective electrode array, modelled by the Nikolskii - Eisenmann equation, was simplex-optimized for the simultaneous determination of Na, K and Ca by flow injection analysis. The array comprised three highly selective electrodes and a fourth, a multiple ionophore electrode, that responded selectively to the three cations, but to varying degrees. The response surface of each electrode in the array was determined by using mixed calibration solution, and the dependence of the model parameters on the analyte concentration. was studied. The advantages of the combination of selective and non-selective electrodes in the array compared with single-electrode measurements and sparingly selective electrode arrays are discussed. The determination of cations in real samples at low and high concentration. with coefficient of variation of 8 and 2.5%, respectively, is demonstrated by the analysis of mineral water and human plasma. The application of an ion-selective (ISE) array modeled via the Nikolskii-Eisenmann equation for the simultaneous determination of sodium, potassium, and calcium in flow injection analysis system is described. The array consists of three highly selective electrodes and a fourth sensor which responds selectively to the three cations but to differing degrees. The response surface of each electrode within the array is determined using mixed calibration solutions and this response modeled using simplex optimization. The dependence of the model parameters on analyte concentration. has been investigated. The kinetics of the selective response have been examined by modeling the potentiometric response of the array at short times following analyte injection and the application of this response for anal. investigated. The combination of sensors employed offers considerable advantage over existing single electrode measurements and arrays containing sparingly selective electrodes, such as prediction polling resulting in improved precision and accuracy, diagnosis of electrode performance without recalibration and accurate characterization of array response using simple models. The ability to determine sodium, potassium, and calcium in real samples at low and high concentrations. to within 8 and 2.5% error, respectively, is demonstrated using mineral water and human plasma samples.
Potassium Sodium Calcium Mineral Plasma Human Electrode Electrode Electrode Electrode Potentiometry

"Ultraviolet And Light Absorption Spectrometry"
Anal. Chem. 1994 Volume 66, Issue 12 Pages 445R-461R
J. A. Howell and L. G. Hargis

Abstract: Anal. applications of UV and visible absorption spectrometry are reviewed with 614 refs.
Spectrophotometry

"Kinetic Spectrophotometric Method For Analysing Mixtures Of Metal Ions By Stopped-flow Injection Analysis Using Partial Least-squares Regression"
Anal. Chem. 1994 Volume 66, Issue 18 Pages 2905-2911
M. Blanco, J. Coello, H. Iturriaga, S. Maspoch, and J. Riba

Abstract: Binary and tertiary mixtures of Co(II), Zn(II) and Fe(III) were analyzed using a stopped-flow injection manifold, in which they were merged with streams of 0.625 mM EGTA in 0.1 M Tris buffer of pH 8.05, water, and 1 mM 4-(2-pyridylazo)resorcinol (PAR). A diode-array detector recorded absorbances at various wavelengths simultaneously. In the first mode, the metal ion solutions were directly injected into the flow stream, where EGTA complexes were formed and the chelator was competitively displaced by PAR. In the second mode, metal-EGTA complexes were formed prior to injection into the flow system; only ternary mixtures were analyzed in this mode. The data from the spectrophotometer were reduced to the absorbances recorded at 500-540 nm at 15 reaction times from 10^-150 s and processed by PC. Partial least-squares (PLS) regression was used to resolve the mixtures on the basis of the differences in the rate of displacement of EGTA by PAR. The data from mode 2 showed that displacement of EGTA was pseudo first-order whereas in mode 1, the displacement rates from the Co and Zn complexes were the same but those for Fe were not first order. In both modes, PLS calibration allowed satisfactory measurement of the transition metal ions.
Cobalt(II) Iron(2+) Zinc(II) Spectrophotometry

"Ion-sensitive Electrodes In Flow Injection Analysis-improved Performance And Unique Applications"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 698-700
Wolfgang Frenzel

Abstract: A review is presented, with 28 references, of the incorporation of ion-sensitive electrodes in flow systems. Aspects discussed include kinetic discrimination, lowering of detection limits, indirect non-titrimetric determination, reverse flow injection analysis calibration, series differential detection and continuous monitoring.
Electrode Potentiometry

"Flow Injection Calibration Techniques"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 663-667
Julian Tyson

Abstract: A review is presented, with 28 references. Examples are described of the various manifolds and methods designed for this purpose, especially for use in conjunction with atomic spectrometry.
Spectrophotometry

"Expansion Of The Dynamic Range Of Flow Injection Analysis Systems For Complete Batch Process Monitoring"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 678-684
C. Thommen, M. Garn und M. Gisin

Abstract: Online monitoring of industrial processes requires a wide dynamic range, and methods to achieve this are discussed. Of two methods described in detail, the simpler involves combination of peak height measurement with electronic dilution or peak-width measurement, the latter being used when the concentration. is too high for peak height to be used. An example given is the determination of aromatic amines. For more precise measurements, gradient dilution can be used with time-variable zone sampling, as in the monitoring of glucose in fermentation processes.
Amines, aromatic Industrial

"Potential Of Modified Reverse Flow Injection Analysis For Continuous Monitoring And Process Control"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 668-674
Wolfgang Frenzel

Abstract: The transient detector response observed after injection of standard solution into a continuously flowing sample stream is a measure of the concentration. of standard added to the continuous sample concentration. Calibration of the monitoring system is discussed and compared with that of other systems. Full details are given for application of the technique in the photometric determination of Cl- in tap water, PO43- in surface water and the potentiometric determination of F-, and each analysis is discussed.
Chloride Phosphate Fluoride Surface Water Potentiometry Spectrophotometry

"New Possibility For The Calibration Of Potentiometric Determinations Under Flow Injection Conditions. 1. Theoretical Fundamentals"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 2 Pages 205-209
H. M&uuml;ller und J. Kramer

Abstract: The factors affecting the dispersion obtained in a flow injection system are discussed. A completely new method of calibration is proposed using the potential of the flow-gradient in FIA. For potentiometric determinations the Nernst equation is combined with the Gauss'ian gamma function. It is found that a simple expression can be used to calculate the concentration of a sample after injection of a standard without explicit knowledge of the Nernst factor. A microcomputer is used for the on-line calculations.
Potentiometry

"Individual And Sequential Flow Injection Spectrophotometric Determination Of Vanadium(V) And Titanium(IV)"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 8 Pages 905-909
Ala'ddin M. Almuaibed and Alan Townshend

Abstract: Sample solution containing VV or Ti(IV) (120 and 80 µL, respectively) was injected into a carrier stream of H2O2 - H2SO4 (2.2 mL min-1) and the absorbances of the red - brown and yellow peroxo-complexes formed were measured at 460 and 410 nm, respectively. For the determination of V, interference by Ti(IV) was overcome by incorporating an online mini-column (5 cm x 2.5 mm) of Dowex-50W (100 to 200 mesh) into the V manifold to remove the Ti complex. The injection valve was modified for determination of VV - Ti(IV) mixtures to introduce two samples sequentially into the reagent stream. One was passed through the cation-exchange mini-column (to measure V alone) and the other through an empty column (to measure V and Ti) before detection of both complexes at 460 nm. Calibration graphs were rectilinear up to 2 mM V and 3.5 mM Ti, with corresponding detection limits of 0.01 mM and 2.5 µM. Sample throughput was 75 h-1 and the coefficient of variation was 1% (n = 10). Sample solution containing VV or Ti(IV) (120 and 80 µL, respectively) was injected into a carrier stream of H2O2 - H2SO4 (2.2 mL min-1) and the absorbances of the red - brown and yellow peroxo-complexes formed were measured at 460 and 410 nm, respectively. For the determination of V, interference by Ti(IV) was overcome by incorporating an online mini-column (5 cm x 2.5 mm) of Dowex-50W (100 to 200 mesh) into the V manifold to remove the Ti complex. The injection valve was modified for determination of VV - Ti(IV) mixtures to introduce two samples sequentially into the reagent stream. One was passed through the cation-exchange mini-column (to measure V alone) and the other through an empty column (to measure V and Ti) before detection of both complexes at 460 nm. Calibration graphs were rectilinear up to 2 mM V and 3.5 mM Ti, with corresponding detection limits of 0.01 mM and 2.5 µM. Sample throughput was 75 h-1 and the coefficient of variation was 1% (n = 10).
Vanadium(V) Titanium(IV) Spectrophotometry

"Direct Determination Of Calcium, Magnesium, Sodium And Potassium In Water By Flow Injection Flame Atomic Spectroscopy, Using A Dilution Chamber"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 8 Pages 975-979
M. de la Guardia, V. Carbonell, A. Morales and A. Salvador

Abstract: The cited elements were determined in water using a dilution chamber to extend the calibration range and allow a single concentration. standard to be used for the calibration of each analyte. A double channel injector and the merging zone technique were used to add La solution to the samples (1:1) and reduce reagent consumption. Samples were analyzed by flow injection flame AAS, peak heights were measured at 422.67, 285.21, 589.00 and 766.49 nm for Ca, Mg, Na and K, respectively. Results agreed well with those obtained by a batch AAS procedure and gave better precision. Sensitivities were 0.0408, 0.046, 0.0122 and 0.20 ppm and detection limits were 2.5, 1.5, 7.0 and 0.5 ppm for Ca, Mg, Na and K, respectively. The sample throughput was ~180 samples h-1. The cited elements were determined in water using a dilution chamber to extend the calibration range and allow a single concentration. standard to be used for the calibration of each analyte. A double channel injector and the merging zone technique were used to add La solution to the samples (1:1) and reduce reagent consumption. Samples were analyzed by flow injection flame AAS, peak heights were measured at 422.67, 285.21, 589.00 and 766.49 nm for Ca, Mg, Na and K, respectively. Results agreed well with those obtained by a batch AAS procedure and gave better precision. Sensitivities were 0.0408, 0.046, 0.0122 and 0.20 ppm and detection limits were 2.5, 1.5, 7.0 and 0.5 ppm for Ca, Mg, Na and K, respectively. The sample throughput was ~180 samples h-1.
Calcium Magnesium Sodium Potassium Environmental Spectrophotometry

"Simultaneous-fluorimetric Methods For The Determination Of Ammonia And Urea By Use Of Flow Injection Configurations With Dual Injection Valves"
Fresenius J. Anal. Chem. 1990 Volume 336, Issue 6 Pages 490-493
Andr&eacute;s Izquierdo, Pilar Linares, M. D. Luque de Castro and Miguel Valcarcel

Abstract: With a parallel-valve configuration, two sample plugs (130 µL for NH3, 230 µL for urea) were simultaneously injected, one into a phosphate buffer (pH 8.0) stream which passed through a reactor containing immobilized urease (to form NH3 from urea) and the other into a borate buffer (pH 9.5) stream. The streams were merged before undergoing fluorimetric reaction with pre-mixed phthalaldehyde and 2-mercaptoethanol solution A delay between the arrival of the plugs at the detector was achieved by use of the enzyme reactor in conjunction with a delay coil in the phosphate stream. For the serial-valve configuration two sample plugs were injected into the phosphate buffer, and separated from each other by the enzyme reactor and the delay coil. Two peaks were obtained, the first giving NH3 concentration. and the second giving the NH3 originally present plus that formed from urea. Both configurations produced similar results, with rectilinear calibration ranges of 0.5 to 6.0 µg mL-1 (for NH3) and 1.0 to 10.0 µg mL-1 (for urea), recoveries of 94 to 107%, and a sampling rate of 60 h-1. The only serious interference was caused by Fe(II). The methods were applied to water samples.
Ammonia Urea Fluorescence

"Online Preconcentration Of Silver On Activated Alumina And Determination In Borehole Water By Flow Injection Atomic Absorption Spectrophotometry"
Fresenius J. Anal. Chem. 1990 Volume 336, Issue 3 Pages 201-204
P. P. Coetzee, I. Taljaard and H. de Beer

Abstract: Silver in borehole water is pre-concentrated on a polyethylene micro-column (3 cm x 1 mm) of activated alumina (basic form) connected to a flame AAS instrument (schematic diagram given). Sample (pH 4.0) is passed through the column for 3 to 6 min at 5 mL min-1 with water as carrier stream, elution is with 0.5 mL of 2 M HNO3 and regeneration is with 0.15 M NH4OH (2 min at 5 mL min-1). The effluent is directed to a nebulizer and analyzed by AAS at 328.1 nm. The calibration graph is rectilinear for up to 100 µg mL-1 of Ag, with coefficient of variation (n = 10) of ±5 and 18% for >10 and 5 µg l-1, respectively. The detection limit is 4 µg l-1. Sodium, Mg and Ca salts at 0.1 M to 0.5 M decrease the Ag signal by 10%.
Silver Borehole Spectrophotometry Sample preparation

"Kinetic Determination Of Creatinine In Biological Fluids By Stopped-flow Injection Analysis"
Fresenius J. Anal. Chem. 1990 Volume 338, Issue 6 Pages 752-754
Beatriz Fern&aacute;ndez-Band, Pilar Linares, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: Serum or diluted urine (130 µL) was injected into a 9 g L-1 NaCl solution and mixed partly along a 100-cm tube merging with the reagent stream. After a 25-cm reactor, the reacting plug reached the flow-cell, where the flow was halted 1 s after the residence time (delay time 28 s). A stop time of 35 s allowed the kinetic curve to be monitored at 500 nm. The pump was automatically started and the baseline was restored. All solution were kept at 25°C. The calibration graph was rectilinear from 3 to 150 µg mL-1 of creatinine. The coefficient of variation was 1.27% (n = 11). The kinetic measurements required no sample pre-treatment except for dilution of urine. The method compared favourably with the standard recommended procedure.
Creatinine Urine Spectrophotometry

"Determination Of Iron(II)-iron(III) And Iron(III)-nickel(II) By Two-component Potentiometric Complexometric Titration"
Fresenius J. Anal. Chem. 1992 Volume 342, Issue 1-2 Pages 54-57
Jolanta Kochana, Katarzyna Madej and Andrzej Parczewski

Abstract: The two-component complexometric potentiometric titration has been applied to the simultaneous determination of Fe(III) and Fe(II), and of Fe(III) and Ni(II) in solution. In each case the two analytes were determined by reading the end-points directly from the titration curve. The end-points are determined in a sense arbitrarily, but they are repeatable and easy to be detected precisely. However, the apparent (found) anal. results are biased. They are effectively correlated with the use of a set of two calibration equations (uncomplete second degree polynomials), which approximately the relationship between found endpoints and true concentrations of analytes in solution The regression coefficients in the equations are determined on the basis of titration data obtained for standard solutions whose compounds correspond to a 22 factorial.
Iron(2+) Iron(III) Nickel(II) Potentiometry

"A Flow System For Calibration Of Dissolved Oxygen Sensors"
Fresenius J. Anal. Chem. 1997 Volume 358, Issue 6 Pages 677-682
P. Jeroschewski A and D. zur Linden

Abstract: Well-defined oxygen standard solutions were obtained by the electrolysis of water in a coulometric oxygen generator. The generator was integrated into a flow system that includes the degassing of the carrier electrolyte, the generation of dissolved oxygen and the temperature control of the carrier electrolyte. The current efficiency of oxygen generation was found to be 100% by the Winkler titration method. Calibrations of a home made laboratory sensor and a WTW CellOx dissolved oxygen sensor have been made in a concentration range of 0.02 to 8 mg/L at temperatures from 5°C to 30°C. The calibration of the WTW sensor on water vapor saturated air was compared with the electrochemical calibration method. Both methods gave reliable results provided that the temperature equilibration between the sensor and the ambient air was successful.
Oxygen Sensor

"Liposome-based Flow Injection Enzyme-immunoassay For Theophylline"
Microchim. Acta 1990 Volume 100, Issue 3-4 Pages 187-195
Tai -Guang Wu and Richard A. Durst

Abstract: A peristaltic pump was used to supply, in 0.1 M Tris buffer (pH 7.2) as carrier, a standard solution of theophylline (I) or plasma sample, in the same buffer, to a column (17.8 cm x 2.5 mm) of glass beads coupled to monoclonal anti-theophylline antibodies. The injector (Rheodyne type 7010) then delivered a solution of liposomes that encapsulated horse-radish peroxidase and had been sensitized with 4-(1,3-dimethylxanthin-8-yl)butyric acid (II). Competition between I and II for the antibodies occured, and unbound liposomes were eluted for post-column reaction with H2O2 and 4-fluoriphenol. This reaction caused release of F-, which was determined with an Orion model 69-09 ion-selective electrode. The column was then washed with glycine - HCl solution to dissociate the antigen - antibody complex and reactivate the column. Calibration graphs are presented for two liposome compositions (10 and 20 miu mL-1 of enzyme activity). I can be detected over the concentration. range 0.2 to 4000 ng mL-1, i.e., a detection limit of 100 fmol in a 0.1 mL sample. For an activity of 10 miu mL-1, the coefficient of variation (n = 6) was 4.6% at the level of 4.3 ng mL-1. The assay takes ~10 min.
Theophylline Blood Plasma Immunoassay Electrode

"HPLC Post-column Derivatization Of Aromatic Amines Using N-methyl-9-chloroacridinium Triflate"
Microchim. Acta 1990 Volume 102, Issue 4-6 Pages 221-232
Myungsoo Kim and James T. Stewart

Abstract: Benzocaine (I) and butesin (II) in mobile phase were separated by HPLC on a column (25 cm x 4.6 mm) of ASI ODS (5 µm) with aqueous 80% methanol as mobile phase (1 mL min-1). Hydralazine (III), isoniazid (IV) and procainamide (V) in mobile phase were separated by HPLC on a column (10 cm x 4.6 mm) of Brownlee RP-8 (5 µm) with 100% methanol - aqueous phosphate buffer of pH 3 (1:1) as mobile phase (1 mL min-1). The column eluates were mixed with N-methyl-9-chloroacridinium triflate in acetonitrile (details given) and detected at 460 nm. Calibration graphs for I and II were rectilinear from 25 to 500 µM; coefficient of variation ranged from 1 to 6%. The limit of detection for I and II was 100 ng mL-1. Recoveries of III, IV and V were >97%, with coefficient of variation of 1.6, 0.5 and 1.4%, respectively.
Amines, aromatic HPLC

"Spectrophotometric Determination Of Carbaryl By Flow Injection Analysis"
Microchem. J. 1988 Volume 38, Issue 3 Pages 370-375
P. Y&aacute;&ntilde;ez-Sede&ntilde;o, C. Nova Nova and L. M. Polo D&iacute;ez*

Abstract: Sample solution (120 µL) was injected into the carrier stream (0.4% NaNO2) which was then mixed with 0.5% sulfanilic acid in a reaction coil (12 cm x 0.5 mm) before passing to a second coil (1.5 m x 0.8 mm) to be mixed with 0.4 M NaOH. The absorbance of the solution was measured at 515 nm. Carbaryl(I) was extracted from formulations with ethanol for 30 min, and a 5 mL portion of ethanolic extract was diluted to 500 mL before injection as above. To determine I in potable water, 20% H2SO4 was added to a 250 mL sample (to pH 5), 2.5 g of anhydrous Na2SO4 was dissolved in the solution, 35 mL of CH2Cl2 was added, the solution was shaken, and the aqueous phase was re-extracted with CH2Cl2 (25 ml). The organic extract was washed, dried on a column of Na2SO4, then evaporated to dryness, and the residue was dissolved in 25 mL of 1% ethanol for analysis as before. Calibration graphs were rectilinear over the ranges 10 to 40, 1 to 10 and 0.1 to 1 ppm of I, and the detection limit was 0.08 ppm. The coefficient of variation was 3.8% at the 0.5 ppm level. Recoveries were quantitative.
Carbaryl Water Spectrophotometry

"Spectrophotometric Determination Of Aniline By Flow Injection Analysis In A Non-aqueous Medium"
Microchem. J. 1989 Volume 39, Issue 1 Pages 20-24
Berman, R.J.;Clark, G.D.;Whitman, D.A.;Christian, G.D.

Abstract: Samples (25 µL) were injected into a carrier stream (2.5 mL min-1) of 0.1 M chloranil in dioxan - propan-2-ol (1:1), and the mixture passed through a PTFE reaction coil (3 m x 0.8 mm) before absorbance measurement at 543 nm. The calibration graph was rectilinear for up to 25 mM aniline; the detection limit was 0.23 mM. Sixty samples can be analyzed in 1 h. The reaction is not specific. Samples (25 µL) were injected into a carrier stream (2.5 mL min-1) of 0.1 M chloranil in dioxan - propan-2-ol (1:1), and the mixture passed through a PTFE reaction coil (3 m x 0.8 mm) before absorbance measurement at 543 nm. The calibration graph was rectilinear for up to 25 mM aniline; the detection limit was 0.23 mM. Sixty samples can be analyzed in 1 h. The reaction is not specific.
Aniline Spectrophotometry

"Flow Injection Analysis And Batch Procedures For The Routine Determination Of N-penicillamine"
Microchem. J. 1990 Volume 41, Issue 1 Pages 2-5
P. Vi&ntilde;as, J.A. Sanchez-Prieto, M.Hernandez Cordoba

Abstract: A capsule was dissolved in water to 250 mL and a suitable portion of the solution was treated with 1 mM Co(II) solution (2.5 ml) and 2 M ammonium acetate (2.5 ml). The mixture was diluted to 25 mL and the absorbance of the yellow complex was determined at 360 nm. Calibration graphs were rectilinear for 0.02 to 0.3 mM of penicillamine. The method was modified for flow injection analysis using peak-height or peak-width methods; in both cases the flow rates were maintained at 3.3 mL min-1. For the peak-height technique, calibration graphs were rectilinear for 0.1 to 2 mM; the sampling frequency was 150 samples h-1. For the peak-width method, response was rectilinear for 50 µM to 0.1M; this method was particularly useful for routine determinations.
Penicillamine N Pharmaceutical Spectrophotometry

"Spectrophotometric Determination Of Vanadium(V), Vanadium(IV), And Vanadium(III) With Pyrogallol In A Flow Injection System"
Microchem. J. 1990 Volume 42, Issue 3 Pages 319-322
B. Haghighi, N. Maleki, A. Massoumi, S. Razi and A. Sapavi

Abstract: Sample solution containing V (100 µL) were injected into a stream of acetate buffer solution (pH 6.0) that had been merged with a stream of pyrogallol (I) solution The I concentration. (1M), the length of the post-injection mixing coil (100 cm), the flow rates of the I and buffer streams (2 mL min-1) and the sample volume were optimized; the average sampling rate was 60 h-1. The absorbance of the resulting complex was monitored at 580 nm. The calibration graph (peak height) was rectilinear in the range 0 to 10 µg mL-1 and the limit of detection was 40 ng mL-1; there was no interference from any closely related ions. The method was applied to different synthetic samples, with good precision and excellent accuracy.
Vanadium(III) Vanadium(IV) Vanadium(V) Spectrophotometry

"Determination Of Glutathione In Biological Material By Flow Injection Analysis Using An Enzymic Recycling Reaction"
Anal. Biochem. 1988 Volume 174, Issue 2 Pages 489-495
F. A. M. Redegeld*, M. A. J. van Opstal, E. Houdkamp and W. P. van Bennekom

Abstract: Rat hepatocyte preparation or rat liver homogenate was deproteinized with HClO4. For determination of oxidized glutathione(I), N-ethylmaleimide was added; the excess was destroyed by alkaline hydrolysis (pH 11.2; 3 M potassium phosphate buffer) and HClO4 was added to neutralize. After centrifugation, the supernatant solution was injected into a carrier buffer (0.4 M potassium phosphate of pH 6.75) for flow injection analysis. The reagent solution (each at 0.2 mL min-1) were 1 mM 5,5'-dithiobis-(2-nitrobenzoic acid) in carrier buffer and 0.5 mM NADPH containing 3 iu mL-1 of glutathione reductase (in carrier buffer). The mixture flowed at 0.6 mL min-1 through a single-bead string reactor for enzymatic recycling before measurement of absorbance at 412 nm. The calibration graphs were rectilinear up to 200 and 400 pmol of oxidized and reduced I, respectively. The detection limit was 1 pmol. Glutathione was determined in isolated rat hepatocytes and results correlated well with those by spectrophotometry (r = 0.977). A sensitive and specific assay for glutathione using a recycling reaction followed by spectrophotometric detection in a flow injection analysis system is presented. The proposed method provides specific amplification of the response to glutathione by combined use of the enzyme GSSG reductase and the chromogenic reagent 5,5'-dithiobis(2-nitrobenzoic acid). Both oxidized (GSSG) and reduced (GSH) glutathione are detected, so that GSSG must be determined separately after alkylation of the GSH with N-ethylmaleimide. The sensitivity is controlled by the number of times the cycle occurs and therefore by the residence time of the sample in the reactor. This time depends on the reactor length and the flow rate. The influence of residence time, temperature, and enzyme concentration on the response has been studied and the optimum reaction conditions have been selected. The sample throughput is as high as 30 h-1 and the detection limit is 1 pmol GSH at a signal-to-noise ratio of 3. The method has been evaluated by the quantification of GSH and GSSG in isolated hepatocytes. A high correlation between the new flow injection analysis method and the original spectrophotometric batch assay has been found (slope = 1.039, intercept = 0.6, n = 216, r = 0.977). The main advantages of the proposed method are high sample throughout, high sensitivity, and good reproducibility.
Glutathione Liver Rat Spectrophotometry

"Determination Of Thiobarbituric Acid-reactive Substances In Oxidized Lipids By High Performance Liquid Chromatography With A Post-column Reaction System"
Anal. Biochem. 1989 Volume 182, Issue 1 Pages 116-120
Kazuaki Yoden* and Toshihiro Iio

Abstract: Free malonaldehyde (I) and other thiobarbituric acid-reactive substances were determined in oxidized lipids (prep. described) by HPLC on a column (15 cm x 6 mm) of Inertsil ODS-2 (5 µm) with linear gradient elution (0.7 mL min-1) from aqueous 50 to 100% methanol over 30 min, and held at 100% methanol for 15 min. The eluate was mixed (0.7 mL min-1) with 0.5% 2-thiobarbituric acid in 0.05 M HCl in a reaction coil (20 m x 0.4 mm) at 55°C and the resulting red pigment was determined fluorimetrically at 553 nm (excitation at 515 nm). The calibration graph was rectilinear up to 4 nM-I and the detection limit was 0.5 nM. The procedure was applied in the analysis of thermally oxidized methyl linoleate, the degradation products of methyl linoleate hydroperoxides and the oxidation products of rat liver microsomes.
Thiobarbituric acid Liver HPLC Fluorescence

"Flow Injection Analysis Of Serum Urea Using Urease Covalently Immobilized On 2-fluoro-1-methylpyridinium Salt-activated Fractogel And Fluorescence Detection"
Anal. Biochem. 1990 Volume 188, Issue 2 Pages 325-329
D. Narinesingh, R. Mungal and T. T. Ngo

Abstract: Serum samples were analyzed for their urea content using fluorescence flow injection analysis incorporating an immobilized urease bioreactor and a gas permeable separator. The urease was immobilized under mild and facile conditions to a hydrophilic 2-fluoro-1-methylpyridinium-activated support. The ammonia released as a result of urease-catalyzed urea hydrolysis diffused through a gas permeable membrane into a constant stream of o-phthaldehyde solution to form a highly fluorescent product with lambda ex at 340 nm and lambda em at 455 nm. Up to 25 serum samples can be analyzed per hour. The within-day coefficient of variation (CV) was 1.12% and the day-to-day CV was 1.25% for serum containing 10.50 mg urea nitrogen dl-1. The bioreactor shows excellent storage (at 4°C) and operational stabilities (at 37°C). Urea was determined in serum by flow injection analysis (illustrated) with urease immobilized on 2-fluori-1-methylpyridinium toluene-4-sulfonate-activated Fractogel. The ammonia released diffuses through a gas-permeable membrane into a stream of phthalaldehyde. The fluorescence of the resulting product is measured at 455 nm (excitation at 340 nm). Calibration graphs were rectilinear up to 1400 mg dl-1 and the detection limit was 0.1 mg dl-1. Recovery was 98 to 103% and coefficient of variation were 1.5%.
Urea Blood Serum Fluorescence

"Fluorometric Determination Of Urinary Kynurenic Acid By Flow Injection Analysis Equipped With A"
Anal. Biochem. 1990 Volume 190, Issue 1 Pages 88-91
Ken-ichi Mawatari, Fumio Iinuma and Mitsuo Watanabe

Abstract: A flow injection analysis involving a photochemical reaction and fluorometric detection has been developed for the determination of urinary kynurenic acid. Kynurenic acid was found to fluoresce on irradiation with ultraviolet light at pH 7.2 in the presence of hydrogen peroxide. This method was applied to flow injection analysis using a new procedure involving a 'bypass line' for the simultaneous determination of urinary kynurenic acid and background fluorescence. The calibration graph showed linearity over the range of 0.20 to 120 pmol. For pretreatment of urinary kynurenic acid, a PRE-SEP C18 cartridge was used. The mean recovery of kynurenic acid from urine was 94.5%. The content of urinary kynurenic acid was 13.0±2.68 µmol/day. There was good correlation (r = 0.9729) between values determined by flow injection analysis and high performance liquid chromatography. Urine, diluted 25-fold with 0.2 M Na2HPO4 - 0.1 M citric acid buffer (pH 3.2), was applied to a PRE-SEP C18 cartridge and kynurenic acid (I) was eluted with phosphate buffer solution (pH 7.2) containing 20% methanol. The eluate was subjected to flow injection analysis with 0.07 M phosphate buffer (pH 7.2) containing 25 mM H2O2 - methanol (8:2) as carrier solution (1.2 mL min-1). After injection into the carrier solution the stream was split; one part was passed through a photochemical reaction coil and the second part, for background correction, bypassed the reaction coil. Fluorescence detection was at 465 nm (excitation at 370 nm). The calibration graph was rectilinear for 0.20 to 120 pmol of I. Recovery was 94.5% and results correlated well (r = 0.973) with those by HPLC.
Kynurenic acid Urine HPLC Fluorescence

"Determination Of Amitriptyline With Bromocresol Purple And Flow Injection Analysis"
Anal. Lett. 1990 Volume 23, Issue 8 Pages 1371-1383
Martinez Calatayud, J.;Martinez Pastor, C.

Abstract: Bromocresol purple gave the best ppt. for the flow injection turbidimetric determination of amitriptyline. The different chemical and flow injection variables were optimized by the univariate method in a continuous-flow procedure. The calibration graph was rectilinear from 30 to 200 ppm of amitriptyline hydrochloride, the coefficient of variation (n = 20) was 1.4% and the injection rate was 39 samples h-1. Dextrose, glutamic acid, sucrose and lactose interfered. The procedure requires no liquid extraction, and was used as a control method in pharmaceutical analysis.
Amitriptyline Pharmaceutical Turbidimetry

"Chemiluminescent Determination Of Ascorbic Acid In Juices"
Anal. Lett. 1990 Volume 23, Issue 12 Pages 2273-2282
Kim, J.M.;Huang, Y.L.;Schmid, R.D.

Abstract: A highly sensitive and rapid chemiluminescent assay method for ascorbic acid (I) was developed. The stopped-flow-analysis method was applied in the measurement of ascorbate concentration. using 10 or 50 µM-H2O2, 0.5 mM luminol and 4 U L-1 of peroxidase to induce the chemiluminescence. The calibration graph was rectilinear from 0.1 to 16 µM-I and coefficient of variation (n = 4) was 2%. Interference was not present. The determination limit obtained is lower than that obtained by the method of Veazey and Nieman (cf. Anal. Chem., 1979, 51, 2092).
Ascorbic acid Fruit Chemiluminescence

"Extractable Sulfate-sulfur, Total Sulfur And Trace-element Determinations In Plant Material By Flow Injection Analysis. 2. Total Sulfur And Copper, Zinc, Manganese And Iron In Plant Material"
Anal. Lett. 1990 Volume 23, Issue 4 Pages 675-702
D. L. Heanes

Abstract: Oven-dried samples (200 to 500 mg) were digested (at 100 samples per day) with HNO3 containing HClO, NH4NO3 and CaCl2 in a Pyrex tube at 60°C to 220°C (details given). The cooled digest was diluted to 15 mL with water and a flow injection analysis (FIA) system was used for the turbidimetric determination of total S in the supernatant solution, with the use of aqueous 0.01% Brij 35 as carrier solution, aqueous 1% Na ascorbate as sample diluent, and 0.25% of Na2EDTA in 0.1 M NaOH and 11% of BaCl2.2H2O in 1% gum arabic as reagent solution (valve switch timing sequence given). The throughput rate was 120 samples h-1. Calibration graphs were rectilinear for 1 to 200 mg mL-1 of sulfate-S in 0.25 M HClO4. The detection limit was 8 mg kg-1 in plant material. In the determination of 100 mg L-1 of sulfate-S in 0.254HClO4 and the analysis of kale, lucerne hay and oat grain, the coefficient of variation was 0.7% (n = 10). The recovery of 0.2% of S in plants was 97 to 104%. There was no interference from 6% of Ca, 5% of Mg, Na or K, 2.5% of Si, or 0.5% of P or N. A procedure for the FIA of Zn, Mn, Cu and Fe with AAS detection was also described.
Sulfate Sulfur Copper Zinc Manganese Iron Vegetable Oat Lucerne Sample preparation Spectrophotometry Turbidimetry

"Evaluation Of Ultra-thin Ring And Band Micro-electrodes As Amperometric Sensors In Electrochemical Flow Cells"
Electroanalysis 1989 Volume 1, Issue 1 Pages 23-33
John W. Bixler*, Michael Fifield, Jordan C. Poler, Alan M. Bond, Wolfgang Thormann

Abstract: The electrodes (0.1 to 0.5 µm thick), on 2- or 4-mm borosilicate- or soda-glass rod, were produced by sputtering, by firing Pt or Au paint, or from Au foil, and were mounted in the working electrode port of a Metrohm EA1096 thick-layer wall-jet flow-through cell. An array of three vapor-deposited Au band electrodes (each 0.1 µm x 0.5 mm), mounted parallel to the flow direction in a thin-layer channel cell, was also constructed. These ultra-thin sensors, together with a jet-centred carbon micro-disc, were characterized by cyclic voltammetry, and were evaluated in the amperometric flow injection mode (vs. a non-aqueous Ag - Ag+ electode) for temporal stability, calibration sensitivity, background signal and flow rate dependence of the analytical signal by injection of ferrocene in acetonitrile containing 0.1 to 10 mM tetramethylammonium perchlorate. The detection limit of 3 to 6 nM obtained with Au-paint ring electrodes on borosilicate glass was an order of magnitude lower than that of any of the other electrodes tested, and analytical signals from the Au-paint and -foil rings, the band array and the carbon micro-disc had the best temporal stability.
Amperometry Voltammetry Electrode Electrode Sensor

"Flow Injection Amperometry Of Cysteine And Glutathione At An Electrode Modified With A Ruthenium-containing Inorganic Film"
Electroanalysis 1990 Volume 2, Issue 2 Pages 107-112
James A. Cox *, Thomas J. Gray

Abstract: A vitreous-carbon electrode modified with a thin film of Ru oxides (prep. described) promotes the diffusion-controlled oxidation of cysteine and glutathione at +0.92 V (vs. Ag - AgCl). In flow injection amperometry in 0.2 or 0.02 M K2SO4 (pH 2.0), log. - log. calibration graphs were rectilinear over three orders of magnitude, and detection limits (injection volume 7.5 µL) were 1 µM. Up to 60 samples h-1 could be analyzed, and there was no evidence of electrode fouling during use. The electrode exhibited no change in sensitivity after regular use during 2 weeks.
Cysteine Glutathione Amperometry Electrode

"Flow-reversal Injection Analysis For Improved Stripping Voltammetry"
Electroanalysis 1990 Volume 2, Issue 2 Pages 127-132
Joseph Wang *, Huang Huiliang, Wladyslaw Kubiak

Abstract: Repeated reversal of the flow direction during deposition in flow injection stripping voltammetry promotes improved plating efficiency and hence better detection limits. In the determination of Pb2+ at a Hg-coated carbon-fiber electrode, a 13-fold enhancement in response was obtained by application of 10 flow oscillations, which corresponded to a detection limit of 7 nM as compared with 90 nM with a once-through system. The calibration graph (15 oscillations) was rectilinear in the range 0.1 to 0.8 µM-Pb (injection volume 0.1 ml); at 0.5 µM (10 oscillations) the coefficient of variation (n = 10) was 6%. The better plating efficiency also permits use of smaller sample volume.
Lead(2+) Voltammetry Electrode

"Determination Of The Pesticide Guthion By Flow Injection Analysis With Amperometric Detection"
Electroanalysis 1990 Volume 2, Issue 6 Pages 487-492
J. Hern&aacute;ndez M&eacute;ndez, R. Carabias Mart&iacute;nez*, E. Rodr&iacute;guez Gonzalo, J. P&eacute;rez Trancon

Abstract: Guthion, a pesticide, was determined by flow injection analysis using single- and three-channel systems with and without a chemical reaction. The experimental variables involved in each case were investigated and optimized, and the analytical features of the two procedures were compared. A method based on the oxidation of anthranilic acid yielded in the alkaline hydrolysis of the pesticide at a glassy carbon electrode is proposed for its determination. The detection limit is 4.1 times 10^-7 M, and the relative standard deviation is 2.2% (n = 10) when the hydrolysis reaction takes place within the three-enamel manifold. The method is based upon the oxidation at a vitreous-carbon electrode of anthranilic acid (I) produced in the alkaline hydrolysis of the cited pesticide (II). A methanolic solution of I is injected (157 µL) into a 0.06 M acetic acid - 0.04 M Na acetate - 20% methanol carrier stream that is subsequently mixed with 0.4 M NaOH and passed through a 2-m reaction coil. Then 0.5 M acetic acid is added to the reaction mixture and the resulting solution is passed through a 49-cm tubular reactor and into the detector cell where I is determined amperometrically at +1.2 V (vs a Ag - AgCl electrode) at a wall-jet vitreous-carbon electrode. The calibration graph is rectilinear for 96.6 µM-II and the detection limit is 0.41 µM. At 38.6 µM the coefficient of variation was 2.2% (n = 10). By carrying out hydrolysis separately and using a single channel flow injection system the limit of detection is reduced to 18 nM-II. In this instance the calibration graph was rectilinear for 28.0 µM-II and for 0.84 µM-(II) the coefficient of variation was 2.5% (n = 10).
Pesticides Guthion Amperometry Electrode Electrode

"Amperometric Flow Injection Analysis Of L-glutamate Using An Immobilized-enzyme Reactor: Amplification By Substrate Recycling"
Electroanalysis 1990 Volume 2, Issue 7 Pages 563-565
Toshio Yao*, Naokazu Kobayashi, Tamotsu Wasa

Abstract: A column (5 mm x 4 mm i.d.) of LiChrosorb NH2 (10 µm) was activated by circulation of 5% glutaraldehyde solution in 0.05 M NaHCO3 for 1.5 h, then washed with 0.1 M phosphate buffer of pH 7.0 before co-loading with glutamate oxidase (8.5 iu) and alanine aminotransferase (118 iu) by circulation of the enzyme solution in the same buffer for 2 h at room temperature The resulting reactor was washed for 3 h with 0.1 M glycine buffer of pH 7.5, and was stored in the 0.1 M phosphate buffer at 5°C when not in use. The reactor was positioned between the injector and a Yanagimoto flow-through Pt electrode in the flow injection system described previously (Anal. Chim. Acta, 1990, 231, 121) for the determination of L-glutamate with use of 1 mM L-alanine in 0.1 M phosphate buffer (pH 7.2) as carrier solution and an applied potential of 0.5 V vs. Ag - AgCl. The reaction principle is described. At the optimum reactor temperature of 37°C and a flow rate of 0.3 mL min-1, the amplification factor was 24; the detection limit was 0.1 µM and the calibration graph was curvilinear. The method could also be used to determine 2-oxoglutarate.
l-Glutamate Amperometry Electrode Electrode

"Precise Analysis Of Silver By Flow Injection Analysis With Stripping Voltammetric Detection"
Electroanalysis 1990 Volume 2, Issue 2 Pages 133-137
Li Qun Zhang, Peter E. Sturrock*

Abstract: Sample solution was introduced into a carrier stream of 0.1 M Al(NO3)3 - 2 mM HNO3 by timed partial-loop injection from a 2 mL sample loop under computer control, and the solution passed into a wall-jet cell equipped with a Pt-disc working electrode, an annular Pt counter electrode concentric with the inlet jet, and an Ag - AgCl reference electrode, the salt bridge of which was concentric with the working electrode. After deposition at 0 V for 30 to 60 s, stripping was carried out by application of either a square-wave or staircase sweep between +0.1 and +0.7 V. The calibration graph was rectilinear for 80 nM to 40 µM-Ag+, and the coefficient of variation ranged from 0.12 to 0.78%. There was no interference from 4 µM-Cd, -Cu, -Fe, -Pb or -V. The method was developed as an indirect means of determining the current efficiencies of Hall cells on a short-term basis.
Silver Voltammetry Electrode

"Determination Of Sterigmatocystin In Fermentation Broths By Reversed-phase High Performance Liquid Chromatography Using Post-column Fluorescence Enhancement"
J. Chromatogr. A 1990 Volume 523, Issue 1 Pages 305-311
Frank L. Neely* and Curt S. Emerson

Abstract: Sterigmatocystin (I, fungal toxin often found in food) was separated from the broth by homogenization with methanol, filtration, extraction of I from the filter-cake with methanol and 0.45 µm re-filtration of the supernatant solution A portion of solution was subjected to HPLC in a column (25 cm x 4.6 mm) of Beckman Ultrasphere C18 (5 µm) with use of a guard column (1.5 cm x 3.2 mm) of Brownlee Newguard RP-18 (7 µm), a mobile phase (0.5 mL min-1) of aqueous 88% methanol, post-column derivatization (reaction coil diameter 0.01 in.) at 35°C with aqueous 5% AlCl3 (added at 0.5 mL min-1) and fluorimetric detection at 455 nm (excitation at 254 nm). The limit of detection was 0.09 ppm, with rectilinear calibration range from 0.1 to 15 ppm and coefficient of variation (n = 12) of 0.2% at 0.82 ppm. A TLC separation on Whatman LK-5D silica with a mobile phase of 1% acetic acid in CCl4 - CHCl3 (1:1) and fluorimetric detection of the same derivative is summarized.
Sterigmatocystin Fermentation broth HPLC Fluorescence Sample preparation

"Phthalaldehyde Post-column Derivatization For The Determination Of Gizzerosine In Fish Meal By High Performance Liquid Chromatography"
J. Chromatogr. A 1990 Volume 515, Issue 1 Pages 527-530
Hiroyuki Murakita and Takeshi Gotoh

Abstract: Fish meal (200 mg) was hydrolyzed with 2 mL of 6 M HCl at 110°C for 22 h, and the digest was filtered and evaporated. The residue was dissolved in 2 mL of 10 mM phosphate buffer (pH 2.6) and cleaned up on a Bond Elut C18 cartrige. Analysis was on a column (15 cm x 4 mm) of Shim-pack ISC-07/S1504, with 30 mM sodium borate buffer (pH 9.8) at 45°C as mobile phase (0.4 mL min-1). The eluate was mixed with 15 mM citric acid containing 0.08% of phthalaldehyde and 0.4% of poly(oxyethylene lauryl ether) (0.2 mL min-1), and detection was by fluorimetry at 410 nm (excitation at 320 nm). The limit of detection was ~0.5 ppm, and the calibration graph was rectilinear for 1000 ng. Recovery of 10 ppm was 98.2%, with a coefficient of variation (n = 5) of 1.5%. The method should be useful, but an unknown interferent was observed.
Gizzerosine Meal HPLC

"Determination Of Pseudouridine In Human Urine And Serum By High Performance Liquid Chromatography With Post-column Fluorescence Derivatization"
J. Chromatogr. A 1990 Volume 515, Issue 1 Pages 495-501
Yoshihiko Umegae, Hitoshi Nohta and Yosuke Ohkura

Abstract: Urine (100 µL) was mixed with 100 µL of 0.5 mM 5-fluorouridine (I; internal standard) and 800 µL of water. Serum (0.5 ml) was mixed with 0.5 mL of 0.05 mM I and 0.5 mL of 2 M HClO4, and the mixture was centrifuged at 1000 g and 4°C for 10 min. The supernatant solution (0.5 ml) was mixed with 65 µL of 2 M K2CO3 and re-centrifuged. An aliquot (100 µL) of either solution was analyzed by HPLC on a column (15 cm x 4.6 mm) of TSK gel ODS-80 (5 µm), with 2 or 4% of methanol in 10 mM phosphate (pH 5.0) as mobile phase (0.5 mL min-1). Detection was at 254 nm, and, after mixing the eluate with 2 mM NaIO4 and 20 mM 1,2-bis-(4-methoxyphenyl)ethylenediamine (each at 0.25 mL min-1), by fluorimetry at 470 nm (excitation at 340 nm). Calibration graphs were rectilinear for 0.5 to 50 nmol of pseudouridine in 100 µL of urine or 0.1 to 4 nmol of I in 0.5 mL of serum. Limits of detection were 40 and 8 nM, respectively.
Pseudouridine Urine Serum Human HPLC Fluorescence

"Determination Of Citrulline And Homocitrulline By High Performance Liquid Chromatography With Post-column Derivatization"
J. Chromatogr. B 1990 Volume 497, Issue 1 Pages 37-43
Ichiro Koshiishi, Yumiko Kobori and Toshio Imanari

Abstract: For determination of citrulline (I) in plasma, samples were extracted with trichloroacetic acid and subjected to HPLC on a column (15 cm x 4 mm) of TSK gel SCX with 50 mM citrate buffer containing 0.3 mM NaCl as mobile phase (0.4 mL min-1). The post-column colorimetric reaction was carried out with phthalaldehyde and N-(1-naphthyl)ethylenediamine; detection was at 520 nm. For homocitrulline (I) in urine, acidified samples were applied to a column of Amberlite CG-120 (H+ form) cation exchange resin; II was eluted with 0.1 M Tris - HCl buffer and subjected to HPLC as described. Both I and II were well separated with no interference from protein amino-acids or urea. Calibration graphs were rectilinear in the ranges 2.6 to 500 and 4.3 to 500 µM, respectively. Results indicated that the level of I in the plasma of uremia patients is higher than that in healthy plasma, and that II is excreted into healthy human urine but not into plasma.
Citrulline Homocitrulline Plasma Human Urine HPLC

"High Performance Liquid Chromatographic Determination Of Proteins By Post-column Fluorescence Derivatization With Thiamine Reagent"
J. Chromatogr. A 1990 Volume 518, Issue 1 Pages 141-148
Toshio Yokoyama, Toshio Kinoshita

Abstract: Proteins in the 70% (NH4)2SO4 fraction of Escherichia coli cell debris were separated on a column (30 cm x 7.5 mm) of TSKgel-G3000SW, with 0.1 M phosphate buffer (pH 7.5) containing 0.1 M Na2SO4 as mobile phase (0.8 mL min-1). The column eluate was mixed with a stream (0.2 mL min-1) of hypochlorite reagent (NaOCl solution containing 0.05 M phosphate buffer of pH 7.5 and 0.1% of Brij-35, adjusted to pH 7.5 and 0.8% available Cl, and chlorination was performed online at 70°C in a PTFE reaction coil. The reaction stream was then mixed online with thiamine reagent (0.2 mL min-1, comprising 4% NaNO2 - 0.02% of thiamine hydrochloride in 0.05 M phosphate buffer of pH 7.5), thiochrome was produced in a second reaction coil at 70°C, and the fluorescence generated was monitored at 440 nm (excitation at 370 nm). Calibration graphs for five proteins were rectilinear from 20 ng to 2 µg injected, and the detection limit of bovine serum albumin was 10 ng. Ionic surfactants did not interfere.
Fluorescence HPLC

"Calibration Principles For Flow Injection Analysis-capillary Electrophoresis Systems With Electrokinetic Injection"
J. Chromatogr. A 1998 Volume 808, Issue 1-2 Pages 219-227
Petr Kubana, Kirsi Tennbergb, Robert Tryzella and Bo Karlberga,*

Abstract: The utility of different calibration techniques in flow injection analysis-capillary electrophoresis systems based on electrokinetic injection has been studied in detail and compared. Best results were obtained with the internal standard method or by applying the conductivity corrected peak area method. These methods yielded a relative error of prediction of less than 6% and can be recommended for quantitative analysis.
Electrophoresis

"High Performance Liquid Chromatographic Analysis Of Unchanged Cis-diamminedichloroplatinum (cisplatin) In Plasma And Urine With Post-column Derivatization"
J. Chromatogr. B 1990 Volume 529, Issue 1 Pages 462-467
Masafumi Kinoshita, Naomi Yoshimura and Hiroyasu Ogata, Daijiro Tsujino, Toshiaki Takahashi, Satoru Takahashi, Yuji Wada and Kazuhiko Someya, Tetsuro Ohno, Keisou Masuhara and Yoshio Tanaka

Abstract: Plasma was ultra-filtered and analyzed directly. Urine was centrifuged and diluted 1:10 before analysis. HPLC was carried out on a column (15 cm x 4.6 mm) of Hitachi No. 3013-N anion-exchange resin (5 µm), with a Guard-Pak CN pre-column and acetonitrile - 10 mM NaCl (17:3) as mobile phase (0.7 mL min-1). The eluate was mixed with 26 µM-K2Cr2O7 (0.14 mL min-1) and 6.6 mM NaHSO3 (0.7 mL min-1), and cisplatin was determined as Pt by AAS at 265.9 nm (heating program given). The limit of detection was 80 ng mL-1 and the calibration graph was rectilinear for 30 µg mL-1. Recovery was 95.0 to 104.0% from plasma and 98.0 to 103.8% from urine, with corresponding coefficient of variation of 4.9 to 7.9% and 3.0 to 5.5%. The method is applicable to pharmacokinetic studies.
Blood Plasma Urine HPLC

"FIA - Extraction Applied To The Limit Test For Heavy Metals"
J. Pharm. Biomed. Anal. 1989 Volume 7, Issue 8 Pages 937-945
Lars-G&ouml;ran Danielsson* and Zhao Huazhang

Abstract: Heavy metals in various samples were determined by flow injection extraction - spectrophotometry (e.g., at 274 nm) as their diethyldithiocarbamate complexes. Analytical parameters were chosen such that the sensitivities for toxic metals were enhanced compared with those for less toxic ones; e.g., at pH 3.5 in the presence of 3 mM EDTA the response to Fe, Mn, Ni and Zn was suppressed, but that to Pb was not. Calibration was effected with standard Pb solution, and the heavy metal content was calculated as Pb. The system was more sensitive than the standard procedure based on precipitation of colloidal sulfides. Relative responses for various ions at pH 3.5 and 4.7 in the presence and absence of EDTA are reported, as are results obtained on analytical-grade salts, pharmaceutical raw materials and household commodities. A method is presented that allows rapid determination of the total concentration of heavy metals in a sample. The method is based on FIA-extraction and photometric measurement of the metals as their dithiocarbamate complexes. The analytical parameters have been chosen such that the sensitivities for toxic elements are enhanced compared with those of less toxic heavy metals. The sampling capacity of the system is 40 samples h-1 and the repeatability (RSD) is 1.9% at 0.1 mg 1-1. Raw materials for the production of pharmaceuticals as well as analytical grade salts and household commodities have been tested.
Metals, heavy Lead Inorganic compound Pharmaceutical Commercial product Spectrophotometry Sample preparation

"Determination Of Penicillin In Pharmaceutical Formulations By Flow Injection Analysis Using An Optimised Immobilised Penicillinase Reactor And Iodometric Detection"
J. Pharm. Biomed. Anal. 1990 Volume 8, Issue 1 Pages 49-60
M. A. J. van Opstal, R. Wolters, J. S. Blauw, P. C. van Krimpen, W. P. van Bennekom and A. Bult

Abstract: An automated assay for the determination of penicillin in formulations suitable for use in pharmaceutical quality control is presented. The method is based on the classical iodometric penicillin assay which is incorporated in a flow injection analysis (FIA) system. The required hydrolysis is performed online by using an immobilized penicillinase reactor. Packed-bed and single-bead-string enzyme reactors are compared. It turns out that a packed-bed penicillinase reactor (10 cm x 1.5 mm i.d.) provides complete hydrolysis within short residence time, while only little back-pressure is generated. This enzyme reactor is stable for at least 9 months. Enzymatic hydrolysis of the β-lactam ring results in the formation of the corresponding penicilloic acid, which consumes iodine. The iodine consumption is determined colorimetrically by measuring the decrease of the absorbance of the blue colored iodine/starch complex. The optimum reactor length and flow rate for the colorimetrical detection reaction are determined. The optimized method is applied to the assay of penicillin in formulations and the results are compared with the 'true' results obtained with a reference method: a mercurimetric titration. The reliability of the flow injection method is evaluated quantitatively by determining the maximum total error (MTE). The reliability is shown to be highest when measuring at a 0.3-mM level. Eight formulations including capsules, tablets and injectables containing penicillin G, amoxicillin or flucloxacillin are assayed. The MTE does not exceed the 6% level and the most probable MTE is between 1.5 and 3.5%. A 30 µL portion of aqueous penicillin (I) solution was injected into a carrier stream (0.3 mL min-1) of 0.2 M potassium phosphate buffer (pH 6.5) and pumped into a packed-bed immobilized β-lactamase reactor (10 cm x 1.5 mm). The penicilloic acid formed was passed into a single-bead-string reactor (25 cm x 1.5 mm) and mixed with a reagent stream (0.7 mL min-1) of aqueous 0.15% starch solution - (0.5 mM I in 0.5 mM KI) - phosphate buffer (1:1:3). The decrease in absorbance of the blue iodine - starch complex was measured at 590 nm. The calibration graph was rectilinear from 0.1 to 0.5 mM I; the detection limit was 0.025 mM. Results compared well with those obtained by mercurimetric titration. Results are presented for the determination of I in eight formulations, including capsules, tablets and injectables.
Penicillin Pharmaceutical Pharmaceutical Pharmaceutical Spectrophotometry

"Rapid Determination Of Benzalkonium Chloride In Pharmaceutical Preparations With Flow Injection Liquid-liquid Extraction"
J. Pharm. Biomed. Anal. 1990 Volume 8, Issue 3 Pages 243-252
J. J. Halvax*, G. Wiese, J. A. Arp, J. M. P. Vermeer, W. P. Van Bennekom and A. Bult

Abstract: Benzalkonium chloride was assayed by online extraction of the benzalkonium ion with picrate to chloroform. The absorbance of picrate was measured. The extractions were performed with a home-made flow injection extraction unit. Calibration curves (1.5-180 x 10^-4% w/v) were straight lines (r = 0.9993) and the relative standard deviation of a series of injections was less than or equal to 2%. Pharmaceutical benzalkonium preparations, containing xylometazoline, timolol, phenylephrine or carbachol could also be assayed. The method was compared with a modified HPLC assay. A flow injection extraction unit is described; the determination is based on the ion-pair extraction of benzalkonium chloride (I) with picrate. Sample solution was mixed with 0.4 mM picrate buffer in the mixing coil of the apparatus followed by extraction of the resulting ion-pair into CHCl3 and measurement of absorbance at 370 nm. The calibration graph was rectilinear from 1.5 to 1800 ppm of I and was prepared from peak-height measurements. The influence of flow rates, the extraction behavior of the I - picrate complex and the adsorption of I on the tubing walls of the apparatus are discussed. The possible interference from other drugs is discussed. Pharmaceutical I preparations containing xylometazoline, timolol, phenylephrine or carbachol were also analyzed.
Benzalkonium chloride Drugs Pharmaceutical Spectrophotometry Sample preparation

"Spectrophotometric Determination Of Adrenaline With An Oxidative Column In A FIA Assembly"
J. Pharm. Biomed. Anal. 1990 Volume 8, Issue 8-12 Pages 663-666
A. Kojo and J. Martinez Calatayud*

Abstract: A single channel FIA assembly is proposed for the spectrophotometric determination of adrenaline, the aqueous sample solution is directly injected into the carrier stream leading the sample through a manganese dioxide column at 80°C, and on to the spectrophotometer flow-cell. The calibration graph is linear up to 17 ppm of adrenaline. The influence of other substances has been studied and the method has been applied to the determination of adrenaline in a pharmaceutical formulation. Sample solution (348.8 µL) was injected into a carrier stream (0.55 mL min-1) of distilled and de-areated water and passed through a column of MnO2, the carrier solution, sample loop and column were maintained at 80°C. The absorbance of the oxidized sample was measured at 300 nm. The calibration graph was rectilinear up to 17 ppm of adrenaline and the detection limit was 0.05 ppm. Coefficient of variation was 0.19% (n=11). Sample throughput was 45 h-1. Interference was present from procaine, amethocaine and picric acid.
Adrenaline Pharmaceutical Spectrophotometry

"FIA - Fluorimetric Determination Of Thiamine"
J. Pharm. Biomed. Anal. 1990 Volume 8, Issue 8-12 Pages 667-670
J. Martinez Calatayuda,*, C. Gomez Benitob and D. Gaspar Gimeneza

Abstract: Sample solution (137.3 µL) was injected into a carrier stream (0.74 mL min-1) of Na2CO3 - boric acid (pH 10) into a coil column (225 cm length) containing immobilized hexacyanoferrate on an ion-exchange resin (cf., Calatayud and Sagrado Vives, Ibid., 1989, 7, 1165) and the fluoresence of the eluate was measured at 440 nm (excitation at 368 nm). Calibration graphs were rectilinear from 0.1 to 4.0 ppm of thiamine. Coefficient of variation was 1.8%. Sample throughput was 28 h-1. Other vitamins, e.g. riboflavin, nicotinamide, pyridoxin, and certain other substances, e.g. caffeine, gave errors of up to 4.3%. A flow injection fluorimetric determination of thiamine is reported. The procedure is based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anionic exchange resin; the fluorescence is monitored in aqueous basic solution. Concentrations of the vitamin of 0.1-4 ppm have been determined; the relative standard deviation was 1.8%. The injection rate was 28 samples/h. The influence of other substances and the determination of the drug in a pharmaceutical formulation are also reported.
Thiamine Pharmaceutical Fluorescence Ion exchange

"Polypyrrole, A New Possibility For Covalent Binding Of Oxidoreductases To Electrode Surfaces As A Base For Stable Biosensors"
Sens. Actuat. B 1990 Volume 1, Issue 1-6 Pages 537-541
W. Schuhmann, R. Lammert, B. Uhe and H. -L. Schmidt

Abstract: Pyrrole was electropolymerized on the surface of a Pt or graphite electrode, the polypyrrole film was nitrated with Cu(NO3)2.3H2O solution in acetic anhydride, and the nitro-groups were electroreduced to amino-groups to which glucose oxidase was bound after carobodi-imide activation. The resulting enzyme electrodes were compared with those prepared by immobilizing glucose oxidase on carbodi-imide-activated electro-oxidized graphite. The polypyrrole-based electrodes showed times to steady-state current 30 s in static and ~10 s in flow injection systems, and also showed good stability. The detection limit was ~5 µM-glucose (cf. ~1 µM for the oxidized graphite electrodes) and calibration graphs were rectilinear over three decades of concentration. Such electrodes can be used for 700 glucose determinations in a flow system.
Electrode Electrode Sensor

"An ISFET-Based Flow Injection Analysis System For Determination Of Urea - Experiment And Theory"
Sens. Actuat. B 1990 Volume 1, Issue 1-6 Pages 433-437
G. K. Chandler, J. R. Dodgson and M. J. Eddowes

Abstract: Preliminary work is presented on an ISFET-based flow injection analysis system for urea determination, which avoids the need for compromise between speed of response and sensitivity found in integrated EnFETs. The response is linear for 30 µL samples in the range 0-25 mM urea; the response time is around 30 s. Theory which calculates the distribution of protons between the various buffers present, assuming 100% conversion of urea, gives a good description of the response and allows optimization of the system to reduce interference by sample buffer and pH variations.
Urea Field effect transistor

"Peristaltic Pumps - Fourier Transforms: A Coupling Of Interest In Continuous-flow Flame Atomic Absorption Spectrometry"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1761-1768
I. L&oacute;pez-Garc&iacute;a, M. S&aacute;nchez-Merlos, P. Vi&ntilde;as and M. Hern&aacute;ndez-C&oacute;rdoba*

Abstract: The modulation imposed by the peristaltic pulses is Fourier-transformed into a frequency spectrum; the amplitude observable at the known pulse frequency can then be distinguished from noise signals. The module of the signal at a frequency of nomega/60 can be used as the analytical signal to lower the limit of determination by a factor of 5-6 with respect to that obtainable by aspiration. Concentrations that are too high to be measured with direct aspiration can be measured by including an auxiliary channel in the manifold to compensate for the difference between the pumping rate and the nebulizer uptake rate and using the amplitude as the analytical signal. Only a single standard solution analyzed under different conditions is required for calibration.
Spectrophotometry

"Flow Injection System For The Simultaneous Determination Of Two Components In A Single Injection And With A Single Detector"
Anal. Sci. 1989 Volume 5, Issue 2 Pages 221-223
T. YAMANE and E. GOTO

Abstract: A flow injection system is described and illustrated that is based on synchronized injection of a large volume of sample and a small volume of reagent into separate carrier streams which then merge at a confluence point. This mixture is then mixed with a chromogenic reagent stream before passing to the reaction coil and then to the detector. The application of the system is illustrated with the determination of Fe(II) and Fe(III) by using ascorbic acid as reagent, 1,10-phenanthroline as chromogenic reagent and detection at 526 nm. Calibration graphs were rectilinear up to 0.1 mM Fe(II) in solution containing 20 µM-Fe(III) and up to 0.1 mM Fe(III) in solution containing 20 µM Fe(II). The coefficient of variation for 10 µM Fe(II) and Fe(III) were 0.5 and 0.9%, respectively.
Iron

"Hydride-generation System With A Hydrogen Separation Membrane For Low-power Inductively Coupled Plasma Emission Spectrometry"
Anal. Sci. 1990 Volume 6, Issue 2 Pages 195-199
H. TAO, A. MIYAZAKI and K. BANSHO

Abstract: A hydrogen separation membrane module is described consisting of hollow aromatic polyimide fibers. The module, operated at ~90°C, was connected to a continuous-flow hydride generator (diagram given) for removal of H before analysis of the hydrides by ICP-AES with Ar as carrier gas. Detection limits obtained for As, Ge, Hg, Sb and Sn are tabulated. The coefficient of variation were 1% at 50 ng mL-1 of each element. Calibration graphs were rectilinear from the detection limit to 100 µg mL-1. Online pre-concentration with use of the module could not be carried out with He instead of Ar as carrier gas beause He permeated the membrane reducing its flow rate.
Arsenic Germanium Antimony Tin Spectrophotometry

"Spectrophotometric Determination Of Calcium With Dicyclohexano-24 Crown-8 And Propyl Orange By Solvent Extraction/flow Injection Method"
Anal. Sci. 1990 Volume 6, Issue 2 Pages 215-220
S. MOTOMIZU, M. OSHIMA, N. YONEDA and T. IWACHIDO

Abstract: The optimum conditions for the cited determination (flow diagram of apparatus given) were: an injection volume of 100 µL; water as carrier stream (0.8 mL min-1); 0.5 mM propyl organge - 0.1 mM LiOH as reagent solution (0.8 mL min-1); 2 mM dicyclohexano-24-crown-8 in benzene - chlorobenzene (1:1) as extractant; a PTFE extraction coil (2 m x 0.5 mm) and detection at 420 nm. The calibration graph was rectilinear up to 0.1 mM Ca and the detection limit was 0.2 µM. The coefficient of variation was 1% at 50 µM-Ca. Results for determination of Ca in river water agreed well with those by EDTA titration. The system can be applied in the determination of Sr and Ba if interference by Ca is accounted for.
Calcium River Spectrophotometry Sample preparation

"Flow Injection Extraction-spectrophotometric Determination Of Copper With Dithiocarbamates"
Anal. Sci. 1990 Volume 6, Issue 3 Pages 415-420
J. SZPUNAR-LOBINSKA and M. TROJANOWICZ

Abstract: Several dithiocarbamates were investigated as reagents for the determination of Cu, and a flow injection method was developed. Sample solution (300 µL) in aqueous NH3 buffer (pH 8.5) as carrier solution was mixed with 0.05% Pb diethyldithiocarbamate in CHCl3, and passed through a coil (400 cm x 0.5 mm). The phases were separated in a membrane separator, and the absorbance of the organic phase was measured at 436 nm. The detection limit is 0.04 ppm of Cu, and the calibration graph is rectilinear up to 2 ppm. The method was applied to water and plants; results were precise and accurate.
Copper Vegetable Vegetable River Spectrophotometry Sample preparation

"Potentiometric Determination Of Reducing Sugars As Borate Complexes Using Hexacyanoferrate(III) - Hexacyanoferrate(II) Potential Buffer And Its Application To Liquid Chromatography"
Anal. Sci. 1990 Volume 6, Issue 5 Pages 777-779
H. OHURA, T. IMATO, S. YAMASAKI and N. ISHIBASHI

Abstract: A system of flow injection analysis with HPLC (diagram given) for the determination of mixed reducing sugars (mono- and di-saccharides) was described with use of a flow-through type oxidation-reduction potential electrode detector cell and a potentiometer. A potential buffer solution comprising 0.1 M [Fe(CN)6]3- - 0.1 M [Fe(CN)6]4- and containing 1 M NaOH was pumped at 0.45 mL min-1 and the 0.5 M borate reagent solution was pumped at 0.5 mL min-1. Sample solution (20 µL) was injected into the borate stream and carried through an anion-exchange column (15 cm x 4.6 mm) of TSK-Gel, Sugar AXI, TOSO for separation at 60°C. The column effluent was merged with the potential buffer solution and the composition change of the buffer caused by reduction of [Fe(CN)6]3- was measured. The calibration graph was almost rectilinear for 2.5 to 10 µM of the mixed saccharides. The coefficient of variation was 1.5% (n = 5) for a 10 µM mixture of cellobiose, maltose and lactose. Detection limits were 0.4 to 2 µM. Sensitivity was similar to or better than amperometric, fluorimetric and spectrophotometric detection methods.
Sugars, reducing Potentiometry HPLC Electrode Ion exchange

"Determination Of The Sulfate Ion Concentration In Rain Water By Flow Injection Analysis Incorporated With A Barium Chloranilate Reaction Column"
Anal. Sci. 1990 Volume 6, Issue 5 Pages 711-714
K. YAKATA, F. SAGARA, I. YOSHIDA and K. UENO

Abstract: Rain water, diluted 1:1 with ethanol, was injected into a carrier solution of aqueous 0.5% NH4Cl - ethanol (1:1; 1.9 mL min-1) and passed through a cation-exchange column (5 cm x 4.6 mm) of Muromac 50W-X 4 (100 to 200 mesh; NH4+ form) and a reaction column (same dimensions) of Ba chloranilate powder (120 mesh). The absorbance of the eluate was monitored at 530 nm. The calibration graph was rectilinear for 4 to 100 ppm of SO42-. Sample throughput was 1 min-1. The results agreed well with those obtained by the standard manual method.
Sulfate Rain Ion exchange

"Flow Injection Determination Of Trace Amounts Of Hydrogen Peroxide With Thio-Michler's Ketone"
Anal. Sci. 1990 Volume 6, Issue 7 Pages 149-150
K. TOEI, T. TAMARU and M. ZENKI

Abstract: Samples (0.13 ml), containing 0.02 to 1 ppm of H2O2, are injected into a carrier stream comprising 25 mM NaI - 0.5 mM ammonium molybdate - 0.2% of Na polystyrene sulfate. This is mixed with a reagent solution comprising 45 µM-4,4'-bis(dimethylamino)thiobenzophenone (I) - 1.3% of Triton X-100 - 13% of methoxyethanol - 0.05 M formate buffer (pH 3.5) in a reaction coil maintained at 30°C. The color change of I (thio-Michler ketone) is measured at 660 nm. Samples could be analyzed at a rate of 42 h-1. The calibration graph was rectilinear over the cited range. The system could be used to determine glucose indirectly, by incorporation of glucose oxidase. The calibration graph was rectilinear for 80 mg l-1. The method was used to determine glucose in urine. Samples (0.13 ml), containing 0.02 to 1 ppm of H2O2, are injected into a carrier stream comprising 25 mM NaI - 0.5 mM ammonium molybdate - 0.2% of Na polystyrene sulfate. This is mixed with a reagent solution comprising 45 µM 4,4'-bis(dimethylamino)thiobenzophenone (I) - 1.3% of Triton X-100 - 13% of methoxyethanol - 0.05 M formate buffer (pH 3.5) in a reaction coil maintained at 30°C. The color change of I (thio-Michler ketone) is measured at 660 nm. Samples could be analyzed at a rate of 42 h-1. The calibration graph was rectilinear over the cited range. The system could be used to determine glucose indirectly, by incorporation of glucose oxidase. The calibration graph was rectilinear for 80 mg l-1. The method was used to determine glucose in urine.
Hydrogen peroxide Glucose Urine Spectrophotometry

"Rapid Microdetermination Of Hydroxyproline In Biomedical Samples By Flow Injection Analysis Using Cysteine As An Antioxidant"
Anal. Sci. 1990 Volume 6, Issue 1 Pages 39-44
K. UCHIDA, M. TOMODA, T. SHIBATA, S. IKEUCHI, T. HASEBE, T. MIWA, T. NOMOTO, K. FUKUSHIMA, S. SAITO and S. INAYAMA

Abstract: Tissue samples are hydrolyzed with 6 M HCl, the mixtures are freeze-dried, and the residues are dissolved in 0.01 M cysteine. Portions are injected into a stream of chloramine T solution (0.7 g L-1 in borate buffer of pH 8.7). Passage through a heating coil at 100°C causes hydroxyproline (I) to be oxidized and decarboxylated to pyrrole. Treatment with a solution of Ehrlich reagent (4-dimethylaminobenzaldehyde) in 10% H2SO4 and 10% Triton X-100 gives a colored product, which is detected at 560 nm. The calibration graph is rectilinear in the range 1 to 80 µg mL-1 of I. Optimization experiments are described especially for concentration. of chloramine T (oxidant) and cysteine (color stabilizer). The method, which avoids use of organic solvents, allows 100 samples to be analyzed in ~5 h. Recoveries of I are 94.8 to 103.7%. Results agreed well with those from a batch method.
Hydroxyproline Skin Spectrophotometry

"Flow Injection Analysis Combined With Atomic Absorption Spectrometry"
Anal. Proc. 1984 Volume 21, Issue 10 Pages 377-378
Julian Tyson

Abstract: In this review, matrix effects, sample pre-treatment and calibration are discussed. (12 references).
Spectrophotometry

"Extended Range Calibrations By Flow Injection Analysis"
Anal. Proc. 1986 Volume 23, Issue 8 Pages 304-305
Julian F. Tyson

Abstract: The calibration range in flow injection analysis is extended by measuring peak width instead of peak height. The upper working limit for flow injection determination of, e.g., NH4+ in a 40 µL sample (manifold described) is increased from 200 to 16,000 ppm. With use of a Tecator 5020 flow injection analyzer., 30 injections h-1 are possible. The coefficient of variation at 125 and 4000 ppm were 1.8 and 0.3%, respectively.
Ammonium Spectrophotometry

"A Semi-continuous Flow Method For The Trace Analysis Of Dissolved Inorganic Antimony"
Anal. Proc. 1989 Volume 26, Issue 1 Pages 32-34
A. T. Campbell and A. G. Howard

Abstract: A 5 mL sample is mixed with 0.5 mL of 1 M KI pre-reductant, and masking agents (if required), and placed in the continuous-flow system (details and diagram given). The solution is acidifed with HCl for determination of total Sb, or mixed with acetate buffer of pH 5.0 for determination of Sb(III), segmented with air, and treated with aqueous 2% NaBH4; the products are swept through a delay coil and stripped from solution in a gas - liquid separator. Stibine is condensed in a cryogenic trap at -196°C, liquid N is then removed and the trap is warmed to room temp., before atomization of stibine and AAS detection at 217.6 nm. Calibration graphs are rectilinear for up to 3 ng of Sb(III) or total Sb, with a detection limit of 24 ng L-1 of total Sb (for a 5 mL sample). Interfering ions are tabulated. The method is applied in determination of total Sb in natural water.
Antimony(3+) Antimony, total Environmental Spectrophotometry

"Enzymic Amplification Reactions: Flow Injection Determination Of NAD+ With Immobilized Alcohol Dehydrogenase And Malate Dehydrogenase"
Anal. Proc. 1989 Volume 26, Issue 2 Pages 56-57
Al'addin M. Almuiabed, Alan Townshend

Abstract: An enzyme cycling flow procedure is described, with diagrams, for determination of NAD+ with use of a column of co-immobilized alcohol dehydrogenase and malate dehydrogenase (I). Detection is at 340 nm after enzymatic reaction on a further column of I, or at 600 nm after acetaldehyde - diethylamine colorimetric reaction. Calibration graphs were rectilinear up to 6 µM-NAD+ with use of either reaction, and the detection limits were both 0.6 µM. The coefficient of variation (n = 10) was 2% for 2.4 µM-NAD+ in either method. An enzyme cycling flow procedure is described, with diagrams, for determination of NAD+ with use of a column of co-immobilized alcohol dehydrogenase and malate dehydrogenase (I). Detection is at 340 nm after enzymatic reaction on a further column of I, or at 600 nm after acetaldehyde - diethylamine colorimetric reaction. Calibration graphs were rectilinear up to 6 µM-NAD+ with use of either reaction, and the detection limits were both 0.6 µM. The coefficient of variation (n = 10) was 2% for 2.4 µM-NAD+ in either method.
Nicotinamide adenine dinucleotide oxidized

"Chemiluminescence Detection Of A Benzodiazepine"
Anal. Proc. 1989 Volume 26, Issue 11 Pages 368-369
Anthony R. J. Andrews, Alan Townshend

Abstract: Seven benzodiazepines (concentration. 1 mM) were examined for chemiluminescence in a flow injection system with various oxidizing and reducing reagents and water as carrier. Only loprazolam (I), with acidic KMnO4 as reagent, gave a measurable response. Optimum conditions for the determination of I were; water as solvent, 0.94 M formic acid, adjusted to pH 0.9 with HCl, as carrier, 0.2 mM KMnO4 as reagent, and a flow rate of 1.3 mL min-1 in the sample and reagent lines. The calibration graph was rectilinear from 0.01 to 5 mM I, and the detection limit was 7 µM. Of 12 metal ions examined, only Fe(II) and Mn(II) interfered. The method could be used to determine I in tablets; excipients did not interfere.
Loprazolam Benzodiazepine, derivatives Pharmaceutical Chemiluminescence

"Flow Injection Analysis Automation With Fluorimetric Detection And Its Application To Vanadium Determination In Petroleum Derivatives"
Analusis 1990 Volume 18, Issue 8 Pages 491-496
Forteza, R.;Oms, M.T.;Cardenas, J.;Cerda, V.

Abstract: A fully automatic fluorimetric FIA system was used to monitor the catalytic auto-oxidation of Na 4,8-diamino-1,5-dihydroxyanthraquinone 2,6-disulfonate (I) by VV with excitation at 524 nm and emission at 582 nm. The FIA system contained an injection module, a manifold constructed from PTFE tubing (i.d. 0.5 mm), a Perkin-Elmer LS5 fluorimeter and an IBM PC. The sample stream was reacted with a stream of 6N-HCl containing 50 µL of injected 0.1 mM I (0.80 mL min-1 each) in a 4-m straight reactor at 30°C. Calibration graphs were rectilinear for 0.2 to 0.8 and 0.8 to 2 mg L-1 of VV. For 0.4 mg L-1 of VV, the coefficient of variation was 1% (n = 17). The tolerance limits of eighteen ions in the determination of 0.5 mg L-1 of VV are tabulated, the most serious interference being observed for Fe3+, Ce4+ and Al3+. The method was applied to Boscan crude and heavy gas oil samples (procedures described).
Vanadium Crude Gas Fluorescence

"Calibrant Solutions For Continuous-flow Urate Analysis: Interference By Formaldehyde"
Ann. Clin. Biochem. 1980 Volume 17, Issue 6 Pages 323-327
R Beetham P G Sanders

Abstract: The use of formaldehyde to preserve aqueous urate calibration solutions has been recommended since 1913, but it interferes in some commonly used methods. At a pH below 8.5 formaldehyde affects the rate of dialysis of urate in Technicon AutoAnalyzer systems. This effect has been studied by variation of the pH at which dialysis takes place. The interference is attributed to the formation of pH-dependent addition products between uric acid and formaldehyde, which have been examined by thin-layer chromatography and mass spectrometry. Recovery experiments on protein-containing solutions show that a purely aqueous urate calibrant solution is satisfactory for use in AutoAnalyzer systems.
Urate Uric acid Clinical analysis

"A New Method For The High Performance Liquid Chromatographic Determination Of TA-870, A Dopamine Prodrug"
Biomed. Chromatogr. 1990 Volume 4, Issue 5 Pages 181-187
Masayoshi Yoshikawa, Hiroshi Endo, Kumiko Hoshino, Yoichi Sugawara, Osasi Takaiti, Susumu Kanda, Kazuhiro Imai

Abstract: A new method for the high performance liquid chromatographic (HPLC) determination of N-(N-acetyl-L-methionyl)-O,O-bis(et hoxycarbonyl)dopamine (TA-870), a dopamine prodrug, in biological fluid has been developed. In order to measure with an electrochemical detector (ECD), TA-870 was passed first through an immobilized carboxylesterase column to be converted to the electrochemically active deethoxycarbonylated TA-870 (DEC-TA-870). The properties of this carboxylesterase immobilized on Sepharose 4B were examined by this flow injection system. Hydrolysis of TA-870 with this immobilized carboxylesterase was a maximum at pH 7-8 and 50°C, and the activity decreased in the presence of organic solvent such as acetonitrile. For the determination of TA-870 in biological fluids, an HPLC-immobilized enzyme-ECD system using a column-switching technique was developed. The blood was deproteinized with ethanol, and TA-870 in the ethanol extracts was adsorbed in Bond Elut C18. The dichloromethane eluate from Bond Elut C18 was injected into the HPLC system. The HPLC apparatus was composed of three pumps, two separation columns (LiChrosorb Si 60 and µBondasphere), a trap column (Bond Elut), an enzyme column, ECD and the column-switching system. The calibration curve for TA-870 in blood was linear in the range from 2 to 200 ng/mL. This new assay method might be useful also for the determination of other catechol ester compounds.
Drugs N-(N-acetyl-L-methionyl)-O,O-bis(ethoxycarbonyl)dopamine Blood HPLC

"Flow Injection Analysis For Trace Amounts Of Silicon On Spectrophotometric Determination Of Molybdosilicic Acid"
Bunseki Kagaku 1988 Volume 37, Issue 10 Pages T115-T119
Motomizu, S.;Korechika, K.

Abstract: Sample solution (320 µL) was injected into a carrier stream (0.7 mL min-1) of water, which was mixed with reagent solution (0.7 mL min-1), containing 6 mM Mo(VI) and 75 mM H2SO4, in a 9-m coil in air at 100°C. The reaction mixture passed through a cooling coil (1 m x 0.5 mm) in a water bath at 20°C, and molybdosilicic acid was measured by its absorbance at 350 nm. The calibration graph was rectilinear for 10 to 1000 ppb of Si. The detection limit was 2 ppb. In determination of 10 and 60 ppb of Si, coefficient of variation (n = 6) were 4 and 0.5%, respectively. Thirty samples could be analyzed in 1 h.
Silicon Geological Spectrophotometry

"Application Of FIA For Process Control Of Wet Non-ferrous-metal Refinement"
Bunseki Kagaku 1988 Volume 37, Issue 11 Pages T171-T175
Shimizu, H.;Murakami, M.

Abstract: Flow injection analysis with spectrophotometry or fluorimetry was applied to the determination of Cd, Cu(II), Fe(III), and Ga. Sample solution (25 µL) was injected into a carrier stream (0.65 to 0.7 mL min-1) to mix with the reagent solution (same flow rate) in the reaction coil, which was connected to a flow cell (18 µL) of a spectrophotometer. The carrier and reagent solution (respectively) were : (i) for Cu(II), acetate buffer (pH 5) and 10 µM-4-methyl-5-(sulfoaminoethyl)-2-(thiazol-2-ylazo)benzoic acid, (ii) for Fe(III), water and 2 M HCl and (iii) for Cd, sodium citrate (9 g) - potassium sodium tartrate (5 g) in 500 mL of 0.2 M NaCl, and 0.5 mM cation. Lumogallion and polyoxyethylene glycol dodecyl ether were used as fluorescent reagent and sensitizer, respectively, for the determination of Ga. The absorbance of the complexes of Cu(II), Fe(III) and Cd were measured at 585, 440 and 447 nm, respectively. The fluorescent adduct of Ga was determined at 560 nm (excitation at 485 nm). Interference from Mn(II), Co(II), Cr(III), Cr(VI) and Ni(II) was observed with the determination of Cd. Bivalent Fe, Ca, As(V) and SO42- interfered in the determination of Ga, but Zn, Cd, Fe(II), In and As(III) did not interfere. Calibration graphs were rectilinear for 0 to 5 µg mL-1 of Cu(II), 0 to 10 g L-1 of Fe(III), 0 to 1 mg L-1 of Cd and 0 to 3 µg mL-1 of Ga. The results agreed well with those obtained by AAS for Cu(II) or Cd, or by titration of Fe(III) with KMnO4.
Cadmium Copper Iron Gallium Industrial

"Chemically Amplified Detection Of Nicotinamide-adenine Dinucleotides In A Flow Injection System With Immobilized-enzyme Reactors"
Bunseki Kagaku 1989 Volume 38, Issue 3 Pages 109-114
Yao, T.;Matsumoto, Y.;Wasa, T.

Abstract: Immobilized reactors containing glucose-6-phosphate dehydrogenase (I) and I - dihydrolipoamide dehydrogenase were used to improve detection of nicotinamide-adenine dinucleotides in a flow injection system containing a vitreous-carbon electrode for amperometric detection. In the former reactor, amplified response was achieved by enzyme reaction - chemical reaction recycling in the presence of 2 mM glucose 6-phosphate (II) and 0.2 mM phenazine methosulfate in carrier solution (0.1 M carbonate buffer of pH 8.5). In the latter reactor, response was amplified by enzyme reaction - enzyme reaction recycling in the presence of 2 mM II and 0.5 mM Fe(CN)63- in 0.1 M carbonate buffer of pH 7.5. Calibration graphs for the two reactors were rectilinear for 0.02 to 10 and 0.05 to 10 nmol injected, respectively. Corresponding detection limits for dinucleotides were ~6 and ~20 pmol. Response amplification factors increased at lower flow rates. Immobilized reactors containing glucose-6-phosphate dehydrogenase (I) and I - dihydrolipoamide dehydrogenase were used to improve detection of nicotinamide-adenine dinucleotides in a flow injection system containing a vitreous-carbon electrode for amperometric detection. In the former reactor, amplified response was achieved by enzyme reaction - chemical reaction recycling in the presence of 2 mM glucose 6-phosphate (II) and 0.2 mM phenazine methosulfate in carrier solution (0.1 M carbonate buffer of pH 8.5). In the latter reactor, response was amplified by enzyme reaction - enzyme reaction recycling in the presence of 2 mM II and 0.5 mM Fe(CN)63- in 0.1 M carbonate buffer of pH 7.5. Calibration graphs for the two reactors were rectilinear for 0.02 to 10 and 0.05 to 10 nmol injected, respectively. Corresponding detection limits for dinucleotides were ~6 and ~20 pmol. Response amplification factors increased at lower flow rates.
Nicotinamide adenine dinucleotide oxidized Amperometry

"Spectrophotometric Determination Of Quaternary Ammonium Ions Based On Micelle Extraction Of Ion Associates"
Bunseki Kagaku 1989 Volume 38, Issue 5 Pages 205-210
Hosoi, Y.;Motomizu, S.

Abstract: The effects of pH and surfactant concentration. on the micelle extraction of ion association complexes of alkylammonium ions and tetrabromophenolphthalein ethyl ester (I) were studied. A flow injection system is described, in which sample solution (120 µL) is injected into a carrier solution (0.8 mL min-1) of water and mixed in a reaction coil (1 m x 0.5 mm) with reagent solution (0.8 mL min-1) consisting of 20 µM-I and 0.02% of Triton X-100 in 0.2 M acetate buffer of pH 4.0. Detection is at 605 nm. Calibration graphs for several quaternary ammonium compounds cover the range up to ~10 µM.
Quaternary Ammonium Ion Spectrophotometry Sample preparation

"Determination Of Calcium By FIA With Glyoxal Bis-(2-hydroxyanil)"
Bunseki Kagaku 1989 Volume 38, Issue 9 Pages T129-T133
Zenki, M.;Kogawa, H.;Nose, K.;Toei, K.

Abstract: Calcium was determined in natural waters by the cited method. Glyoxal bis-(2-hydroxyanil) reagent (0.05%), 0.2 M NaOH and water were used as reagent, buffer and carrier solution, respectively, and were propelled (0.6 mL min-1) by plunger micropumps. Sample solution (290 µL) was injected into the carrier solution, mixed with reagent solution and then passed to a PTFE reaction coil (8 m x 0.5 mm). The absorbance of the red solution obtained was measured at 520 nm. The calibration graph was rectilinear for up to 1.2 ppm of Ca and the detection limit was 5 ppb. The coefficient of variation (n = 10) were 1.2 and 0.22% at 0.4 and 1 ppm of Ca, respectively. Results agreed well with those obtained by AAS. Calcium was determined in natural waters by the cited method. Glyoxal bis-(2-hydroxyanil) reagent (0.05%), 0.2 M NaOH and water were used as reagent, buffer and carrier solution, respectively, and were propelled (0.6 mL min-1) by plunger micropumps. Sample solution (290 µL) was injected into the carrier solution, mixed with reagent solution and then passed to a PTFE reaction coil (8 m x 0.5 mm). The absorbance of the red solution obtained was measured at 520 nm. The calibration graph was rectilinear for up to 1.2 ppm of Ca and the detection limit was 5 ppb. The coefficient of variation (n = 10) were 1.2 and 0.22% at 0.4 and 1 ppm of Ca, respectively. Results agreed well with those obtained by AAS.
Calcium Environmental

"Indirect Spectrophotometric Determination Of Fluoride By FIA Using Arsenazo III - Uranium Complex"
Bunseki Kagaku 1989 Volume 38, Issue 9 Pages 424-428
Zenki, M.;Sai, K.;Ye, Y.;Toei, K.

Abstract: Lanthanum (III), Th(IV) and U(VI) complexes of arsenazo III were evaluated as reagents. Optimum arsenazo III concentration, metal ion concentration, pH, reaction coil length and sample volume were investigated. The U(VI) complex was preferred. A 48 µM-arsenazo III solution (pH 2.8) was used as reagent solution Sample solution (196 µL) was injected into water (carrier solution); PTFE tubing (20 cm x 0.5 mm) was used as the reaction coil. The absorbance was measured at 606 nm. Cation interference was eliminated with use of a cation-exchange column. The calibration graph was rectilinear up to 1.5 ppm of F- and the detection limit was 50 ppb. The coefficient of variation was 0.45% for 0.5 ppm of F- (n = 10). The method was applied in determination of F- in well waters. Lanthanum (III), Th(IV) and U(VI) complexes of arsenazo III were evaluated as reagents. Optimum arsenazo III concentration, metal ion concentration, pH, reaction coil length and sample volume were investigated. The U(VI) complex was preferred. A 48 µM-arsenazo III solution (pH 2.8) was used as reagent solution Sample solution (196 µL) was injected into water (carrier solution); PTFE tubing (20 cm x 0.5 mm) was used as the reaction coil. The absorbance was measured at 606 nm. Cation interference was eliminated with use of a cation-exchange column. The calibration graph was rectilinear up to 1.5 ppm of F- and the detection limit was 50 ppb. The coefficient of variation was 0.45% for 0.5 ppm of F- (n = 10). The method was applied in determination of F- in well waters.
Fluoride Environmental Spectrophotometry

"Potentiometric FIA Of Acids And Bases In Nonaqueous Solvents And Its Application To Lubricating Oils"
Bunseki Kagaku 1990 Volume 39, Issue 2 Pages 109-114
Katafuchi, A.;Imato, T.;Yagi, J.;Takahara, K.;Ishibashi, N.

Abstract: Sample (200 µL) was injected into an ethanol stream and merged with 5 mM tetrabutylammonium butyrate - 5 mM butyric acid buffer solution containing 0.1 M LiCl. The change in pH was measured with use of a glass electrode. The method was applied in the determination of organic acids and aliphatic and aromatic amines. Calibration graphs covered the range 0 to 5 mM. The coefficient of variation was 0.5% and the analysis time was 40 samples h-1. The method was also applied in the determination of the alkalinity of lubricating oils.
Acids, organic Amines, aliphatic Amines, aromatic Alkalinity Oil Potentiometry Electrode

"Spectrophotometric Flow Injection Analysis Measurement Of Ethanol Content In Distilled Alcoholic Beverages Using Sulfonazo-III-barium Complex"
Bunseki Kagaku 1990 Volume 39, Issue 10 Pages 597-599
Zenki, M.;Sakita, E.;Hironaka, T.;Toei, K.

Abstract: Sample solution (180 µL) was injected into a carrier stream (0.5 mL min-1) of water and reacted with a reagent solution (0.5 mL min-1) of 0.01 M acetate buffer (pH 3.5) containing 0.1 mM sulfonazo III and 40 µM of Ba2+ with detection at 640 nm. The calibration graph was rectilinear up to 50% of ethanol. Coefficients of variation (n = 5) for 10 and 30% ethanol were 0.51 and 0.87%, respectively. The results obtained agreed well with certified values.
Ethanol Beverage Spectrophotometry

"Determination Of Serum Urea Using An Open-tubular Immobilized-enzyme Reactor"
Bunseki Kagaku 1990 Volume 39, Issue 11 Pages 755-760
Yasuda, K.;Takata, Y.

Abstract: An open-tubular enzyme reactor, consisting of urease immobilized on the inner surface of aminosilanized silicone rubber tubing, and an ammonium-selective electrode using nonactin were prepared and connected sequentially for the determination of serum urea by a flow injection method. The optimum conditions were: a sample size of 20 µL; a pH of 6.5 and a carrier solution flow rate of 1.0 mL min-1. The calibration range was from 2.0 to 300 mM urea and results correlated well with those obtained by colorimetry.
Urea Blood Serum Electrode

"Determination Of Oxalate By Flow Injection Analysis (FIA) With Electrogenerated Chemiluminescence Detection"
Bunseki Kagaku 1990 Volume 39, Issue 6 Pages 323-326
Uchikura, K.

Abstract: Sample (10 µL) was injected into the carrier stream of water (0.3 mL min-1) and mixed with reagent solution (0.8 mL min-1) of 10 mM H2SO4 containing 0.12 mM tris(bipyridyl)ruthenium dichloride (I). The oxidation potential of the working electrode in the home-made electrochemical reactor, in which tris(bipyridyl)ruthenium3+ was continuously generated from I, was maintained with a potentio-galvanostat. Calibration graphs were rectilinear up to 16 pmol of oxalate. The detection limit was 0.3 pmol and the coefficient of variation was 2.3% (n = 5). The method was applied to the determination of oxalate in urine. Relative chemiluminescence intensities are tabulated for >30 compounds; tryptophan interferes.
Oxalate Urine Chemiluminescence

"Hydroxylaminolysis Of β-lactams And Its Use For The Determination Of Penicillins By Flow Injection Analysis"
Cesk. Farm. 1990 Volume 39, Issue 2 Pages 77-79
Karlicek, R.;Solich, P.

Abstract: A three-stream (0.6 mL min-1 each) system was used, containing three coils in series, of length 25, 50 and 100 cm (A, B and C, respectively). A sample (85 µL) was injected into a stream of reagent solution of pH 6.2 composed of 0.1 M hydroxylammonium chloride and 0.15% Brij-35 in aqueous 25% ethanol, the mixture was passed through reaction coil A (for hydrolysis of β-lactam rings), then acidified to pH ~1 by mixing with a stream of 0.5 M H2SO4 in coil B, merged with solution comprising 12.8 g of (NH4)2Fe(SO4)2 and 1 mL of 15% Brij-35 in 100 mL of 0.05 M H2SO4 - ethanol (3:1), and passed through coil C. The absorbance of the colored complex formed with Fe(III) was measured at 505 nm. Calibration graphs were rectilinear for 0.25 to 3 mg mL-1 of ampicillin, benzylpenicillin, procaine penicillin or phenoxymethylpenicillin, and the detection limits were ~0.1 mg mL-1. The coefficient of variation (n = 6 to 10) were 1.5% for ~1 mg mL-1 of individual penicillins. The method is suitable for analysis of pharmaceuticals; throughput is 50 h-1.
Penicillins Ampicillin Benzylpenicillin Penicillin procaine Phenoxymethylpenicillin Pharmaceutical Spectrophotometry

"Multivariate Approach For The Simultaneous Determination Of Total Biomass And Glucose From A Yeast Fermentation By Sequential Injection Analysis"
Chem. Anal. 1995 Volume 40, Issue 4 Pages 455-471
Baxter, P.J.;Christian, G.D.;Ruzicka, J.

Abstract: The sequential injection system (diagram given) was incorporated into the circulation line of the fermentation unit. Samples (50 µL) of fermentation liquor were carried to a flow cell (Analyst, 1994, 119, 1807) in Trinder reagent (2 ml/min). The flow and stirring were stopped for 3.5 min, resumed for 20 s to dilute the sample, then stopped again while spectra were recorded from 402-800 nm with 2 nm resolution. The flow cell was then rinsed with 6 mL carrier. The assay time was 8 min. A calibration set of samples in which glucose was determined using a manual Trinder assay, and biomass was determined by the dry weight method, was used to calculate linear partial least squares calibration models. The models had excellent predictive ability for 1 g/kg biomass (average errors 3.68-6.15%). The predictive ability for 10 mg/dl glucose was less good, but identification of pulse spikes in the fermentation broth was possible.
Biomass Glucose Fermentation broth Spectrophotometry

"Determination Of Magnesium By Flame AAS Detection With Flow Injection Analysis"
Chem. Pap. 1990 Volume 44, Issue 3 Pages 339-346
Kuban, V.;Komarek, J.;Cajkova, D.;Zdrahal, Z.

Abstract: The single-channel experimental arrangement (cf. Gallego et al., Atomic Spectrosc., 1985, 6, 16) included a capillary dispersing flow injection system of PTFE capillaries with a pulse-free flow of carrier medium provided by hydrostatic pressure, a rotatory loop injector, and an AAS instrument with a Mg hollow cathode lamp and an acetylene - air flame at a slot burner. The sample of an aluminate luminophore (Ba0.9Mg2Al16O27Eu0.1) was fused with Na2CO3 and Na2B4O7, the melt was dissolved in warm 2 M HCl, and the solution was diluted to be 0.1 M in HCl before injection (20 µL volume) into 1% sulfosalicylic acid solution as carrier. The effects of carrier medium, injected sample volume, length of dispersion coil and flow rate on the absorption signal were evaluated. Calibration procedures based on peak heights, peak areas or peak widths at constant height gave rectilinear graphs up to 1.5, 2.0 and 1000 µg mL-1, respectively, of Mg in the injected solution. A reverse standard-additions method gave good precision and overcame the effects of interfering substances. Recovery of 2.5 µg mL-1 of Mg added to luminophore solution was quantitative; for 125 µg mL-1 the repeatability was 2.5% (n = 10).
Magnesium Spectrophotometry

"Simultaneous Determination Of 2-deoxyglucoseSimultaneous Determination Of 2-deoxyglucose"
Chem. Pharm. Bull. 1990 Volume 38, Issue 4 Pages 963-965
Umegae, Y.;Nohta, H.;Ohkura, Y.

Abstract: Sample solution (0.1 ml) was injected on to a TSK gel Sugar AXG column (15 cm x 4.6 mm) operated at 60°C with 1 M borate buffer (pH 9.0) as mobile phase (0.4 mL min-1). The effluent was mixed with 15 mM meso-1,2-bis-(4-methoxyphenyl)ethylenediamine in aqueous 30% ethanol - 0.6 M NaOH (0.3 mL min-1) and passed through a reaction coil (20 m x 0.5 mm) at 140°C and a cooling coil (1 m x 0.5 mm), and the fluorescence was measured at 460 nm (excitation at 330 nm). Calibration graphs were rectilinear for up to 100 nmol injected, the detection limits for 2-deoxy-D-ribose, 2-deoxyglucose (I), rhamnose, L-fucose and glucose (II) were 21, 26, 27, 18 and 28 pmol, respectively, and the respective coefficient of variation (n = 10) at 1 nmol were 1.7, 1.5, 2.1, 1.5 and 1.9%. The method was applied to determine I and II in deproteinized serum, with L-fucose as internal standard.
Glucose 2-Deoxyglucose Serum Rat HPLC Fluorescence

"Measurement Of Transient Signals In Flame Atomic Absorption Spectrometry - A Theoretical Approach"
Chem. Pap. 1991 Volume 45, Issue 1 Pages 69-74
E. BEINROHR

Abstract: The measurement of peak height and peak area of transient signals in flame atomic absorption spectrometry was compared from the point of view of calibration, dynamic response range and versatility. Theoretical considerations imply that the measurement of peak area enables a simple and universal quantitation due to the direct proportionality of peak area to the absolute amount of analyte entering the nebulizer. At instrumental parameters kept constant peak area does not depend on the concentration profile of the sample solution entering the nebulizer.
Metals, heavy Spectrophotometry

"Fast Online Digital Filtering"
Chemom. Intell. Lab. Syst. 1989 Volume 6, Issue 3 Pages 191-201
Sarah C. Rutan

Abstract: Fast online digital filtering techniques permit accurate estimation of chemically interesting parameters from noisy measurements in real time. With the use of appropriate hardware and programming languages, both recursive and nonrecursive filtering algorithms can be used to smooth spectral data, determine calibration parameters for a FIA system, or help in the analysis of kinetic data. The traditional nonrecursive, Savitzky-Golay smoothing filter and the Bromba-Ziegler rccursive implementation for spectral smoothing are discussed. ln addition, the use of the recursive Kalman filter algorithm for parameter estimation for both linear and nonlinear problems is described Fast online digital filtering techniques permit accurate estimation of chemically interesting parameters from noisy measurements in real time. With the use of appropriate hardware and programming languages, both recursive and nonrecursive filtering algorithms can be used to smooth spectral data, determine calibration parameters for a FIA system, or help in the analysis of kinetic data. The traditional nonrecursive, Savitzky-Golay smoothing filter and the Bromba-Ziegler rccursive implementation for spectral smoothing are discussed. ln addition, the use of the recursive Kalman filter algorithm for parameter estimation for both linear and nonlinear problems is described

"Investigation Of The Error Structure Of The Calibration Curve For Periodate Determination By Flow Injection Analysis And Chemiluminescence Detection"
Chemom. Intell. Lab. Syst. 1991 Volume 12, Issue 1 Pages 39-47
N. P. Evmiridis* and E. M. Papamichael

Abstract: Experimental data on periodate determination by flow injection analysis and chemiluminescence detection is fitted to a model equation using the pattern search method. A large number of parameter estimates are obtained from simulated data generated by means of a computer program implemented by a random number generator and their parameter estimate means and variances are compared with the set of parameters obtained from the experimental data. The %-bias, %-excess variance, skewness and excess kurtosis, of the parameter estimates from the simulation study are also calculated to determine the effect of errors on the parameter values. The procedure was followed for different criteria of convergence of the fitting routine and type of errors in the response value and outliers selected at random. The statistical parameters of the model equation parameter estimates are compared in relation to the various convergence criteria for best performance.
Chemiluminescence

"Design Of Experiments For A Precise Estimation Of The Calibration Curve Of Periodate In Its Determination By Flow Injection Analysis And Chemiluminescence Detection"
Chemom. Intell. Lab. Syst. 1995 Volume 30, Issue 2 Pages 227-237
Emmanuel M. Papamichaela, Nickolaos P. Evmiridisb,*, Nickolaos Thanasouliasb and Despina Stefanoua

Abstract: A design of experiments method based on the criterion of D-optimality is presented. It is applied to the estimation procedure of the parameters of a periodate calibration curve described by a model equation of the form y = ax(2)/(bx + c root x + 1) and giving the maximum possible precision using three experimental measurements. The use of four or five experimental measurements for producing the calibration curve was not found more advantageous than that of three. Simulated data were generated, for the three optimal points, and a large number of parameter estimates were obtained under constant and/or relative errors (in y) showing a robust behaviour. The %-bias and the %-excess variance based on the simulated data were found to be non-significant. An experimental design method based on the D-optimality principle was developed. The method was applied to the estimation of the calibration curve of periodate. The use of three optimal-design points were found to be as good as the use of four or five points. The advantages of the method are discussed and parameter estimates obtained with the optimal experimental design exhibited %-bias and %-excess variance based on the simulated data which were not significant. (10 references)
Periodate Chemiluminescence

"Gradient Techniques In Flow Injection Analysis: State Of The Art And Unexplored Possibilities"
Chim. Oggi 1989 Volume 7, Issue 3 Pages 87-91
LUQUE DE CASTRO M. D.

Abstract: A review is presented including sections on flow injection titration, gradient-dilution, pH-gradient and merging-zone techniques and automated calibration methods. (93 references).

"Automated Determination Of Cholinesterase Activity In Plasma And Erythrocytes By Flow Injection Analysis, And Application To Identify Subjects Sensitive To Succinylcholine"
Clin. Chem. 1989 Volume 35, Issue 1 Pages 77-80
P Laine-Cessac, A Turcant and P Allain

Abstract: The cited determination was carried out with use of a flow injection system incorporating a robotic sample preparation and injection unit, a spectrophotometer and an Apple computer. Plasma or haemolysate (5 µL) was mixed with 0.1 M phosphate buffer (pH 7.5) and 10 µL of substrate solution (succinylcholine, butyrylcholine or acetylcholine) and the mixture was heated at 30°C for 20 min. The reaction was stopped by the addition of 10 µL of physostigmine. The choline formed was determined by addition of a color reagent, containing choline oxidase (forming H2O2), peroxidase, phenol and 4-aminoantipyrine and, after further heating, the absorbance was measured at 500 nm. The calibration graph was rectilinear for 0.5 to 4 mM choline. The results using the three substrates correlated well (r 0.94), and the between-day coefficient of variation for plasma analysis was 7% (n = 12). The preferred substrate is succinylcholine. The use of the flow injection system decreases the volume of reagent and sample solution required by a factor of ten.
Enzyme, cholinesterase Succinylcholine Blood Plasma Cell Spectrophotometry Clinical analysis

"Heterogeneous Enzyme Immunoassay Of α-fetoprotein In Maternal Serum By Flow Injection Amperometric Detection Of 4-aminophenol"
Clin. Chem. 1990 Volume 36, Issue 11 Pages 1941-1944
Y Xu, B Halsall and WR Heineman

Abstract: A sandwich-type heterogeneous enzyme immunoassay with flow injection analysis for α-fetoprotein (AFP) in human serum has been developed. 4-Aminophenol, the product of enzymatic reaction, is detected amperometrically. The interassay CV for this electrochemical enzyme immunoassay was less than 8.2%, with a minimum detection limit for AFP of 0.163 µg/L. The calibration curve had a linear range of 0.316-100 µg/L. Studies with 48 human maternal serum samples, comparing results by this method with those by a commercial kit, showed a good correlation (r = 0.961). This procedure provides an alternative method for determining low concentrations of AFP in human maternal serum.
α-Fetoprotein 4-Aminophenol Serum Human Immunoassay Amperometry Clinical analysis

"Fluorometric Determination Of Carnitine In Serum With Immobilized Carnitine Dehydrogenase And Diaphorase"
Clin. Chem. 1990 Volume 36, Issue 12 Pages 2072-2076
K Matsumoto, Y Yamada, M Takahashi, T Todoroki, K Mizoguchi, H Misaki and H Yuki

Abstract: A fluorometric flow injection method for determining carnitine with use of immobilized enzymes carnitine dehydrogenase (EC 1.1.1.108) and diaphorase (EC 1.8.1.4) was developed and applied to the assay of carnitine in serum of patients treated with valproic acid. After fractionation and hydrolysis of carnitines in serum samples by perchloric acid and potassium hydroxide, liberated carnitine was converted to resorufin by immobilized carnitine dehydrogenase and diaphorase in the presence of β-NAD+ (1.0 mmol/L), resazurin (12.5 µmol/L), and Tris acetate (0.6 mol/L, pH 9.0) at 37°C. The fluorescence intensity of resorufin was monitored at lambda Ex 560 nm and lambda Em 580 nm. The calibration curve was linear for carnitine amounts from 0.1 to 1.0 nmol. Quantitative analytical recovery and satisfactory within- and between-run imprecision of carnitine in each carnitine fraction were obtained. Interference by bilirubin, serum albumin, and hemoglobin was negligible. Carnitine deficiencies were detected in about 20% of the valproic acid-treated patients (n = 198). The present method should be useful for monitoring carnitine deficiencies in clinical laboratories.
Carnitine Blood Serum Fluorescence Clinical analysis

"Flow Injection System Based On The Sandwich Technique For Saving Expensive Reagents"
Clin. Chim. Acta 1991 Volume 203, Issue 1 Pages 67-76
Alberto N. Araujo, Jos&eacute; L. F. C. Lima, Juli&aacute;n Alonso-Chamarro*, Jordi Bartrol&iacute; and Manel Poch

Abstract: We report the application of a sandwich technique in flow injection systems which afford low consumption of expensive reagents and two reagent recirculation systems. The potential applicability of the technique thus developed was assessed by determining glucose in serum samples by the enzymatic glucosidase/peroxidase method. It was possible to perform up to 450 determinations with the same amount of reagent used to perform 50 determinations by batch procedures. The sampling rate was 80 determinations per hour with a 0.9% relative standard deviation. Serum was subjected to flow injection analysis with mixing with phosphate buffer solution (pH 7.4) and 11 mM phenol - 0.8 mM 4-aminoantipyrine - peroxidase (900 iu l-1) - glucose oxidase (15,000 iu l-1) and detection at 520 nm. An eight-port injection valve (cf. Alonso et al., Anal. Chim. Acta, 1987, 199, 191) was used to reduce reagent consumption along with a recycling system for the enzyme reagent solution The within-batch coefficient of variation (n = 10) was 0.9%. The method was used to perform 450 determinations with the same amount of reagent used to perform 50 determinations by the batch procedure. The sampling rate was 80 determinations h-1. The results compared well with those obtained using a Hitachi 735 batch analyzer..
Glucose Serum Human Spectrophotometry Clinical analysis

"Bi-enzyme Reactor For Electrochemical Detection Of Low Concentrations Of Uric Acid And Glucose"
Clin. Chim. Acta 1995 Volume 239, Issue 2 Pages 153-165
Ottilia Elekes, Danila Moscone, Kor Venema and Jakob Korf*

Abstract: Human serum (4 µL) was diluted 50- to 100-fold with PBS of pH 7.4 containing 2 mM EDTA and 0.5 mM ferrocenemonocarboxylic acid (buffer A), then left for >6 min before analysis. Portions (2.5 µL) were injected into buffer A and carried at 150 µL/min to a sandwich-type enzyme reactor kept at 30°C containing either uricase and horseradish peroxidase or horseradish peroxidase and glucose oxidase physically co-immobilized between cellulose nitrate filters. The reduction current was measured using a vitreous C electrode held at 0 mV vs. Ag/AgCl and a PTFE/C counter electrode. The calibration graphs were linear for up to 200 µM-uric acid and 1 mM glucose; the detection limits were 30 and 60 nM, respectively. The recoveries of uric acid and glucose were 98-102% and 98-109%, respectively, the within-run RSD were 2% and 3%, respectively (n = 10), and the between-day RSD were 4% and 3%, respectively (n = 10). The results agreed with those obtained using conventional clinical laboratory methods. Sample throughput was 60/h. An enzyme-based flow injection amperometric analysis system for monitoring of uric acid and glucose is described. The oxidase and peroxidase enzymes are physically coimmobilized in a sandwich-type reactor and ferrocene serves as a mediator. The assays are based on the measurement of a reduction current resulting from the enzymatic reactions, at a glassy carbon electrode held at 0.00 mV (vs. Ag/AgCl). The high selectivity (ascorbic acid did not interfere) is coupled to high sensitivity (a detection limit of 30 and 60 nmol/l for uric acid and glucose, respectively; signal/noise = 3) and good stability (the enzymes remained active for more than 6 weeks at 30°C). The usefulness of the assay in clinical chemistry is illustrated by the measurement of human serum uric acid and glucose concentration. The results obtained were in fairly good agreement with those obtained using conventional hospital laboratory methods.
Glucose Uric acid Serum Human Amperometry Electrode Clinical analysis

"Chloride Analysis Of Soil Leachate Using The TRAACS 800 Analyzer"
Commun. Soil Sci. Plant Anal. 1990 Volume 21, Issue 13-16 Pages 1689-1693
Tel, D.A.;Heseltine, C.

Abstract: Soil samples were extracted with 0.1 M NaNO3, 0.1 M HNO3 or water by shaking for 10 min or setting the solution aside overnight. The extract was passed through a 12-in. dialyser to remove interferents before continuous-flow reaction with Hg(SCN)2, methanol, HNO3 and Fe(NO3)3 and measurement of Fe(SCN)3 formed at 480 nm. Calibration graphs were rectilinear from 4 to 400 and 40 to 4000 mg L-1 of Cl-. The coefficient of variation (n = 30) was 0.34% at 100 mg of Cl- and 0.30% at 1 g L-1 of Cl-.
Chloride Environmental

"Simultaneous Determination Of Calcium And Potassium, Magnesium And Sodium, And Potassium And Sodium In Wine Using Flow Injection Analysis Manifolds With A Dialysis Unit"
Connaiss. Vigne Vin 1990 Volume 24, Issue 4 Pages 167-176
J.L.F.C. LIMA, A.O.S.S. RANG EL, M.M. ROQUE DA SILVA

Abstract: A dialysis unit was incorporated into a flow injection analyzer. manifold in order to achieve the large dilutions required for analysis and to halve the stream to allow simultaneous determination of two cations. Schematic diagrams are presented to give full details of reagents, flow rates and mixing times for the determination of Mg and Ca, using AAS detection, and K and Na using flame photometric detection. Calibration graphs were rectilinear from 5 to 300, 9 to 1500, 7 to 120 and 3 to 180 mg L-1 for Na, K, Mg and Ca, respectively. The coefficient of variation (n = 10) were 1% for Ca and Mg and 6% for Na and K. Sample throughput was 120 h-1. Results are presented for the analysis of a number of wines and agree well with those obtained by standard procedures.
Potassium Calcium Magnesium Sodium Wine Spectrophotometry

"Flow Injection Techniques In Atomic Spectroscopy"
Fenxi Huaxue 1986 Volume 14, Issue 7 Pages 549-556
Fang, Z.L.

Abstract: A review is presented of the application of flow injection systems in AAS and in ICP spectrometry, with consideration of sampling, calibration and pre-concentration procedures and hydride-generation and cold vapor AAS techniques. (47 references).
Spectrophotometry Spectrophotometry Spectrophotometry Spectrophotometry

"Application Of Flow Injection Analysis To Clinical Chemistry. Determination Of Creatinine In Serum"
Fenxi Huaxue 1988 Volume 16, Issue 12 Pages 1116-1118
Xia, B.;Liu, S.

Abstract: A flow injection system is described, in which creatinine(I) is determined with use of picric acid as chromogenic reagent; the absorbance is measured at 505 nm. The calibration graph is rectilinear from 1 to 20 mg L-1 of I in serum or urine. The coefficient of variation (n = 10) is 1.8%. Sixty samples can be analyzed in 1 h.
Creatinine Blood Serum Urine Clinical analysis Spectrophotometry

"Determination Of Trace Platinum By Flow Injection Analysis - Adsorptive Stripping Voltammetry And Catalytic Polarographic Hydrogen Wave"
Fenxi Huaxue 1990 Volume 18, Issue 1 Pages 20-24
Wei Guizhen Lu Zongpeng* Alan M.Bond

Abstract: Platinum solution (0.1 µg mL-1; 100 µL) is injected into the flow injection analyzer. and reacts in a stream (0.27 mL min-1) of 0.002% hydrazine sulfate - 0.36 M H2SO4 and 0.04% formaldehyde - 0.36 M H2SO4. Detection is by adsorptive stripping voltammetry at -0.3 V for 60 s and measurement of the catalytic hydrogen wave at -0.8 V. Recoveries were 93.7 to 100% with a coefficient of variation of 5%. The calibration graph was rectilinear for 10 pg to 1 ng of Pt. Twenty samples can be run per hour. The method was applied in the analysis of urine, fish meal, milk powder, ox liver, minerals and organoplatinum compounds.
Platinum Urine Powder Liver Geological Meal Voltammetry Polarography

"Studies On Flow Injection Analysis Of Platinum Metals. 4. Iridium - Potassium Iodate - α-naphtholphthalein System"
Fenxi Huaxue 1990 Volume 18, Issue 3 Pages 237-239
He, X.;Cai, Y.;Hu, Z.D.

Abstract: Iridium catalyses the decoloration of α-naphtholphthalein by KIO4. Based on this reaction, a flow injection analysis method for determining Ir(IV) was developed. The reaction mixture comprised 10 mM KIO4, 0.3 mM α-naphtholphthalein, and Na2B4O7 - NaOH buffer solution (pH 10), at 80°C, and detection at 640 nm. The sampling rate was 61 h-1. The calibration graph was rectilinear for 0.05 to 0.40 µg mL-1 of Ir. The detection limit was 0.02 µg mL-1. The coefficient of variation for simulated samples were 1.0 to 1.3%.
Platinum(IV) Iridium(4+) Spectrophotometry

"Stopped-flow Catalytic Spectrophotometric Determination Of Trace Manganese"
Fenxi Huaxue 1990 Volume 18, Issue 11 Pages 1041-1043
Li, K.;Ren, Y.

Abstract: A flow injection analysis method is proposed (diagram given). Natural water, containing 180 ng of Mn, is mixed with 2 mL of 9 mM nitrilotriacetic acid solution (pH 3.8; I), 5 mL of 0.2 M Na acetate - acetic acid buffer (pH 3.8) and diluted with water to 25 mL. Three reagent streams of viz, 20 µM-Malachite green (C.I. Basic Green 4), 10 mM KIO4 and 10 mM I solution in buffer solution (pH 3.8), are pumped (2 mL min-1) into a reactor for 1 to 2 min with a stopped-flow time of 10 min. The mixture is mixed with a carrier stream of test solution (2 mL min-1) at 52°C in a 2-m coil with detection at 615 nm. The calibration graph was rectilinear for up to 7.2 ng mL-1 of Mn2+ and the detection limit was 0.07 ng mL-1. The coefficient of variation was 3.9%.
Manganese Environmental Spectrophotometry

"Enhancement Effect Of Organic Reagent And Carrier Stream On Sensitivity Of Chromium In Flow Injection Atomic Absorption Spectrometry"
Fenxi Huaxue 1990 Volume 18, Issue 10 Pages 955-957
Wei, J.H.;Lin, F.;Wang, X.S.

Abstract: Steel (0.1 g) was dissolved in aqua regia and diluted with water and then with ethanol. A 300 µL aliquot of the solution was injected into the flow injection analyzer. and reacted with a reagent stream of 10% Na dodecyl sulfate solution (12.5 mL min-1) for analysis by AAS. The calibration graph was rectilinear up to 1.5 µg mL-1 of Cr; the detection limit was 62 ng mL-1. To overcome matrix interference, Fe3+ ( 0.2 mg mL-1) was added to the standard solution The method was 7.6-fold more sensitive than methods which do not employ the organic solvent and reagent; interference from Fe3+ and other ions was also eliminated. The coefficient of variation was 1.4% and the sampling rate was 100 h-1.
Chromium Spectrophotometry

"Single Standard Flow Injection Analysis. Determination Of Copper, Lead, Zinc In Arsenical Pyrite By Gradient Calibration - Atomic Absorption Spectrometry"
Fenxi Huaxue 1992 Volume 20, Issue 11 Pages 1269-1272
Gan, X.X.

Abstract: The instantaneous dispersion coefficient for the cited flow injection analysis - AAS system was determined using Cu as a reference element (details given) and the calibration graph was constructed using a single standard. Sample solution (35 µL) was injected into a carrier stream of water (4.6 mL min-1) for the determination of Cu, Pb and Zn in arsenical pyrite. Equations are given for calculation of the concentration. of these elements. Coefficients of variation were 3%. Sampling speed was 240 h-1.
Copper Lead Zinc Inorganic compound Spectrophotometry

"Determination Of Cobalt(II) With Alizarin Violet Chemiluminescence System By Flow Injection Analysis"
Fenxi Shiyanshi 1989 Volume 8, Issue 2 Pages 27-29
Zhang Wumin, Zhong Shiming, Hu Hejin and Gong Jianyi

Abstract: Cobalt was determined by mixing the sample with 0.2 M NaOH, 1.25 mM hexadecylammonium bromide and alizarin violet in a flow injection system (diagram given) with chemiluminescence detection. The calibration graph was rectilinear from 0.02 to 60 µg L-1 of Co and the detection limit was 3.2 ng l-1. The coefficient of variation at 10 µg L-1 was 0.27%. The method can be applied to the determination of Co in hair.
Cobalt Hair Chemiluminescence

"Determination Of Micro-amounts Of Beryllium By Direct Spectrophotometry And Flow Injection Analysis"
Fenxi Shiyanshi 1990 Volume 9, Issue 6 Pages 28-30
Chen Xingguo, Xu Yanjun and Hu Zhide

Abstract: Beryllium bronze (0.2 g) was digested by heating with concentrated HNO3 or HCl - H2O2 and the digest was heated to remove HNO3 or H2O2, cooled and diluted to 100 mL with water. A 1 mL portion of the solution was mixed with 1 mL of 0.5 M KI and 2 mL of 4% ascorbic acid solution and the mixture was centrifuged. The supernatant solution was diluted to 50 mL with water. For direct spectrophotometric determination of Be, a portion of the sample solution was mixed with 2.5 mL of aqueous 0.1% eriochrome cyanine R (C.I. Mordant Blue 3) solution, 5 mL of ammonium acetate buffer (pH 7), 1.5 mL of aqueous 1% phosphatidylcholine solution and water to 25 mL and, after 30 min, the absorbance was measured at 608 nm (ε =80,000) vs. a reagent blank. Beer's law was obeyed from 20 to 80 ng mL-1 of Be and recoveries were 92 to 104%. For flow injection analysis, a Teactor FIA 5020 Analyser and a spectrophotometric detection system were used. The calibration graph was rectilinear from 0.04 to 2 µg mL-1 of Be and the detection limit was 20 ng mL-1. The coefficient of variation was 1% and recoveries were from 97 to 105%. Tolerance limits of foreign ions are listed.
Beryllium Spectrophotometry

"Enzymic Determination Of Glucose, Sucrose And Maltose In Food Samples By Flow Injection Analysis"
Food Chem. 1990 Volume 35, Issue 2 Pages 109-116
S. M. Tzouwara-Karayanni* and S. R. Crouch

Abstract: Wheat flour (1 g) was mixed with ethanol (1 ml) and the mixture was diluted to 10 mL with water. After centrifugation (20 min at 1000 rpm), the supernatant solution was analyzed. Soft drinks were degassed, and honey was diluted (1:10) before analysis. Wine needed no pre-treatment. For determination of glucose (I), sample solution (0.1 to 1 ml) were diluted to 10 mL with 0.05 M phosphate buffer and then passed through a single bead string reactor containing glucose oxidase. The eluate from this reactor was mixed with a reagent stream containing peroxidase (0.8 mg mL-1), 1 mM 4-aminoantipyrine and 1 mM 3,5-dichloro-2-hydroxyphenylsulfonic acid in 0.05 M phosphate buffer and passed through a plain single bead string reactor. The absorbance was measured at 510 nm. For determination of sucrose (II), the samples were treated with invertase; for the determination of maltose (III) samples were treated with maltase. Calibration graphs were rectilinear from 0.01 to 0.08% of I and III and from 0.01 to 0.12% of II. Results compared well with those by the AOAC method. Recoveries were quantitative.
Glucose Sucrose Maltose Wine Soft drink Spectrophotometry

"Identification Of Chemical Behaviour Of Chromium In Water By Flow Injection Spectrophotometry"
Gaodeng Xuexiao Huaxue Xuebao 1990 Volume 11, Issue 2 Pages 140-143
Wei, Q.;Wang, S.;Wang, L.

Abstract: A method is described for the sequential determination of Cr(VI) and total Cr in water by flow injection analysis - spectrophotometry. Chromium(VI) was measured directly after treatment with diphenylcarbazide and total Cr was measured after the pre-oxidation of Cr(II) to Cr(VI) in a PbO2 column at 80°C. Calibration graphs were rectilinear from 0.5 to 3.0 mg mL-1. Sample throughput was 120 and 200 h-1 for total Cr and Cr(VI), respectively.
Chromium(VI) Chromium Water

"Calibration Methods For Atomic Spectral Analysis Using Flow Injection Techniques"
Guangpuxue Yu Guangpu Fenxi 1991 Volume 11, Issue 2 Pages 41-47
Fan, S.;Fang, Z.L.

Abstract: A review is presented, with 17 references, on the principles, operation and application of calibration methods for atomic spectrometry.
Spectrophotometry

"Determination Of Manganese In Vegetables And Medicinal Plants Using Flow Injection System"
Indian J. Technol. 1990 Volume 28, Issue 2 Pages 78-80
Devi, S.

Abstract: Sample solution (20 µL) was injected into a flowing stream (1 mL min-1) of methanolic 1 mM 2-acetylpyridine thiosemicarbazone (I) and buffer solution (pH 9.0), and the Mn(II) - I complex was extracted into CHCl3 by passage along a 50-cm coil. The phases were separated in a PTFE separator, and the absorbance of the organic phase was measured at 410 nm. The calibration graph was rectilinear for 50 to 150 µM-Mn, and the detection limit was 0.5 µM. The sampling rate was 60 h-1. The method was applied to plant material after dry ashing and acid dissolution. Results showed good agreement with those of AAS.
Manganese Vegetable Plant Sample preparation Spectrophotometry Sample preparation

"Automatic System For Simultaneous Determination Of Nitrates And Nitrites In Waters"
Int. J. Environ. Anal. Chem. 1989 Volume 35, Issue 3 Pages 161-167
J. Maim&oacute;; A. Cladera; F. Mas; R. Forteza; J. M. Estela a; V. Cerd&aacute;

Abstract: In the flow injection analysis system described, the sample is split into two streams, one of which is directly treated with azo-dye reagent and passed to the sample flow cell of a double-beam spectrophotometer where the absorbance due to NO2- is measured. The other stream passes through a reduction micro-column (6 cm x 1 mm) of copperized cadmium where NO3- is reduced to NO2-. The sample is then treated with the azo-dye reagent, and the overall mixture is passed to the reference cell of the spectrophotometer where the abosrbance due to the sum of NO2- and NO3- is measured; NO3- is determined from the difference in absorbance values. The calibration graphs were rectilinear for 10 to 200 mM NO3- and 2.5 to 50 µmM-NO2-, respectively. The technique has been automated by connecting a digital potentiometer, used as a data-acquisition interface for an Amstrad 128 microcomputer, to the register output of the spectrophotometer. Software for data storage and processing is described. Up to 60 samples per hour can be analyzed. In the flow injection analysis system described, the sample is split into two streams, one of which is directly treated with azo-dye reagent and passed to the sample flow cell of a double-beam spectrophotometer where the absorbance due to NO2- is measured. The other stream passes through a reduction micro-column (6 cm x 1 mm) of copperized cadmium where NO3- is reduced to NO2-. The sample is then treated with the azo-dye reagent, and the overall mixture is passed to the reference cell of the spectrophotometer where the abosrbance due to the sum of NO2- and NO3- is measured; NO3- is determined from the difference in absorbance values. The calibration graphs were rectilinear for 10 to 200 mM NO3- and 2.5 to 50 µmM-NO2-, respectively. The technique has been automated by connecting a digital potentiometer, used as a data-acquisition interface for an Amstrad 128 microcomputer, to the register output of the spectrophotometer. Software for data storage and processing is described. Up to 60 samples per hour can be analyzed.
Nitrate Nitrite Environmental Spectrophotometry Potentiometry

"Spectrophotometric Determination Of Mercury(II) By Flow Injection Analysis"
Int. J. Environ. Anal. Chem. 1990 Volume 41, Issue 1-2 Pages 39-46
M. D. Mateo; R. Forteza; V. Cerd&aacute;

Abstract: A method is proposed that uses inhibition by Hg(II) of the catalysis by iodide of the As(III) - Ce(IV) reaction. Sample (125 µL) was injected into a stream (0.7 mL min-1) of 0.04 M Ce(IV) in 1.75 M H2SO4 which was then merged with a stream of 150 ng mL-1 of KI and 0.1 M As(III) same flow rate and acid concentration.) and fed through a reaction coil (6 m x 0.5 mm) at 55°C before detection of unused Ce(IV) at 460 nm. The rectilinear calibration range was 2 to 40 ng Hg mL-1, with coefficient of variation (n = 10) of 1.5% at 20 ng Hg mL-1.
Mercury(II) Water Sea Spectrophotometry

"Application Of A Continuous-flow Technique For Calibration And Measurement With Ion-selective Electrodes"
Izv. Khim. 1990 Volume 23, Issue 4 Pages 534-541
Ilcheva, L.;Nwajagu, C.;Vasileva, V.;Injova, D.

Abstract: For calibration, solutions containing the appropriate ions for the corresponding ion-selective electrode were placed in a flow-through cell, containing the electrode, and diluted with a suitable solution (details given). The change in potential with time was recorded and used to construct a graph of pX (where X is the ion determined) vs. potential; this was used as the calibration graph for determination of X in the solution passed through the cell at the same rate as the diluent in the calibration; interference by accompanying ions and hence selectivity was determined analogously. Results agreed well with those obtained by conventional calibration for solid membranes. For plastic membranes, results at relatively high rates of dilution deviated from those of conventional calibration.
Electrode

"Application Of A Continuous-flow Technique For Calibration And Measurement With Ion-selective Electrodes"
Izv. Khim. 1990 Volume 23, Issue 4 Pages 534-541
Ilcheva, L.;Nwajagu, C.;Vasileva, V.;Injova, D.

Abstract: For calibration, solutions containing the appropriate ions for the corresponding ion-selective electrode were placed in a flow-through cell, containing the electrode, and diluted with a suitable solution (details given). The change in potential with time was recorded and used to construct a graph of pX (where X is the ion determined) vs. potential; this was used as the calibration graph for determination of X in the solution passed through the cell at the same rate as the diluent in the calibration; interference by accompanying ions and hence selectivity was determined analogously. Results agreed well with those obtained by conventional calibration for solid membranes. For plastic membranes, results at relatively high rates of dilution deviated from those of conventional calibration.
Electrode

"Utility Of Automation In Malt Quality Assurance"
J. Am. Soc. Brew. Chem. 1997 Volume 55, Issue 2 Pages 35-37
M.-J. S. Maurice, M. J. Munar, and B. R. Sebree

Abstract: In the past, individual malthouses maintained on-site laboratories, capable of handling limited numbers of samples on a daily basis. Cost-effectiveness dictated the streamlining and centralization of quality assurance laboratories, which must be prepared to analyze more samples for more parameters. The availability of reference-quality automated methods allows precise analysis with minimization of cost and turnaround time. The various capacities in which a company may benefit from automating their laboratory systems will be discussed. 5 References
Malt

"Liquid Chromatographic Method For Quantitation Of Glyphosate And Metabolite Residues In Organic And Mineral Soils, Stream Sediments And Hardwood Foliage"
J. AOAC Int. 1989 Volume 72, Issue 2 Pages 355-360
Thompson DG, Cowell JE, Daniels RJ, Staznik B, MacDonald LM

Abstract: Soil, sediment, foliage and deposit collectors (polyethylene sheets) were extracted with aqueous 0.5 M NH3 and the extract was applied to an AG 1-X8 anion-exchange column, with elution with 0.5 M NH4HCO3. After removal of bicarbonate by repeated evaporation and dissolution in water, further cleanup was effected on a Dowex 50W-X8 cation-exchange column. The aqueous eluate was evaporated to dryness and the residue was dissolved in 5 mM KH2PO4 for HPLC on a column (10 cm x 4.6 mm) of Aminex A-9 equipped with a guard column of the same material and operated at 50°C with 5 mM KH2PO4 (pH 1.9) buffer in aqueous 4% methanol as mobile phase (0.5 mL min-1). After post-column derivatization with ninhydrin at 100°C, glyphosate (I) and its metabolite aminomethylphosphonic acid (II) were detected at 570 nm. Calibration graphs were rectilinear for 0.05 to 3.0 µg of I and 12.5 to 750 ng of II, and detection limits ranged from 0.01 to 0.1 µg g-1.
Glyphosate Environmental River Plant LC Sample preparation

"Continuous-flow Vapor Generation For Inductively Coupled Argon Plasma Spectrometric Analysis. 1. Selenium"
J. AOAC Int. 1990 Volume 73, Issue 3 Pages 404-410
Tracy ML, M&ouml;ller G.

Abstract: Sample (~1.5 g of solid or ~10 mL of liquid) is wet ashed with HNO3, H2SO4 and HClO4 at ~310°C; details are presented for treatment of different samples. The digest is cooled to room temp., 5 M HCl is added and the solution is diluted. In a simple continuous-flow manifold, sample solution is mixed with 12 M HCl and then 0.6% NaBH4 solution The H2Se produced is separated off by a standard pneumatic neublizer, and Se is determined by ICP-AES at 196.090 nm. The detection limit is 0.4 µg l-1, or 4 µg kg-1 for a nominal 1-g sample. The calibration graph is rectilinear for 4 mg kg-1. The method has been applied to biological tissues and fluids and to water. Results show good agreement with those by AAS and NAA.
Selenium Biological tissue Water Spectrophotometry

"Simple Flow Injection Method For The Determination Of Blood Glucose Using A Technicon Immobilized-enzyme Coil"
J. Autom. Methods Manag. Chem. 1989 Volume 11, Issue 2 Pages 87-88
SVEINBJ&Ouml;RN GIZURARSON

Abstract: Sample solution was injected into the carrier solution [55.46 mM PIPES - 2.63 mM MgCl2 - 0.015% Brij 35 - 0.8 mM ATP - 1.1 mM NAD+], which then passed to the Technicon enzyme coil on which hexokinase and glucose-6-phosphate dehydrogenase were immobilized. The solution then passed to the detector for detection of glucose at 340 nm. The calibration graph was rectilinear for up to 3.3 mM glucose and the detection limit was 0.1 mM. The mean coefficient of variation was 1.5%.
Glucose Blood Spectrophotometry

"Calibration In Process Monitoring By Using Unsegmented Continuous-flow Systems"
J. Autom. Methods Manag. Chem. 1989 Volume 11, Issue 6 Pages 260-265
M. D. LUQUE DE CASTRO and M. VALCARCEL

Abstract: A review is presented, with 14 references, of the role of analytical chemistry in process monitoring and control. Online monitoring is particularly suitable, allowing automation. Calibration and recalibration are discussed. An overview is presented of the different aspects of the role of analytical chemistry in process monitoring and control. On-line monitoring is currently the most attractive option in this area, especially with unsegmented-flow techniques. In addition to allowing automation of these systems, the variety of ways in which calibration and recalibration can be performed allows their adaptation to any situation by using extremely simple, home-made manifolds. The most relevant designs are presented and critically discussed in this paper.

"Automatic-determination Of Malate Dehydrogenase Activity With A Flow Injection Multidetection System"
J. Autom. Methods Manag. Chem. 1990 Volume 12, Issue 2 Pages 49-52
J. M. FERN&Aacute;NDEZ-ROMERO and M. D. LUQUE DE CASTRO

Abstract: Serum was subjected to flow injection analysis with mixing with 0.1 M phosphate buffer solution (pH 7), 50 mM oxaloacetate in buffer solution and 10 mM NADH in 30% ethylene glycol, followed by multipeak detection at 340 nm. The manifold includes a valve for closing the circuit along which the reacting plug is continuously circulated, and the absorbance is measured at a conventional spectrophotometer included in the circuit, each peak corresponding to one passage of the plug through the flow cell of the instrument. The calibration graph was rectilinear from 0.02 to 2.00 iu L-1 of malate dehydrogenase and the coefficient of variation (n = 11) was 0.1 to 0.9%. Recovery was 96 to 103%.
Enzyme, malate dehydrogenase Serum Human Spectrophotometry

"Automatic Continuous Online Monitoring Of Salicylic Acid And Acetylsalicylic Acid [aspirin] In Pharmaceuticals"
J. Autom. Methods Manag. Chem. 1990 Volume 12, Issue 6 Pages 263-266
J. M. L&Oacute;PEZ FERN&Aacute;NDEZ, M. D. LUQUE DE CASTRO, and M. VALC&Aacute;RCEL

Abstract: An asymmetrical flow injection analysis (FIA) merging-zones manifold has been developed for the simultaneous determination of salicylic acid (I) and aspirin at a sampling frequency of 30 h-1. The manifold is based on dual injection of two sample micro-volume into two sample plugs, one of which is prehydrolyzed on injection into an NaOH stream and is circulated through a longer channel than the other plug, so yielding two FIA peaks corresponding to salicylic acid and the overall content, respectively. Complexation between the Fe(III) reagent continuously introduced into the system and salicylic acid is monitored photometrically at 520 nm. Calibration graphs are rectilinear for 100 to 600 mg L-1 of I and 300 to 1800 mg L-1 of aspirin, with coefficient of variation of 0.4 and 0.5%, respectively. The manifold was successfully applied to the dissolution testing of aspirin tablets.
Acetylsalicylic acid Salicylic acid Pharmaceutical

"Automatic Calibration For Online Process Monitoring In Continuous-flow Systems"
J. Autom. Methods Manag. Chem. 1995 Volume 17, Issue 1 Pages 17-20
MANUEL AGUDO, ANGEL R&Iacute;OS, MIGUEL VALC&Aacute;RCEL, and ANDREI DANET

Abstract: Automatic calibration in a continuous-flow system was achieved by incorporating a flow gradient unit in the sample channel. The unit (cf. Anal. Chim. Acta, 1990, 239, 211) was controlled via a switching value so that a concentration gradient of the standard was delivered into the system, with the concentration varying with time after the flow-rate gradient was started. This enabled the calibration to be checked as frequently as was required. The system was applied to the determination of hydrazine (I) in water. The sample stream (1.4 ml/min) was merged with a stream (0.4 ml/min) of 0.5 M HCl and then with a stream (0.4 ml/min) of 4% 2,4-dimethylaminobenzaldehyde in methanol/HCl and passed through a reaction coil (625 cm x 0.8 mm i.d.) before detection at 460 nm (manifold illustrated). The calibration graphs generated using a standard I solution of 0.5, 1 or 1.5 µg/ml were linear. The RSD was 1.5%. The results for the analysis of I in water using a 1 µg/ml standard solution for calibration after every three samples are presented.
Hydrazine Water Spectrophotometry

"Development Of A Gas Diffusion FIA System For Online Monitoring Of Ethanol"
J. Biotechnol. 1990 Volume 14, Issue 1 Pages 127-140
Wolfgang K&uuml;nnecke and Rolf D. Schmid*

Abstract: A flow injection analysis (FIA) system for online monitoring of ethanol in cultivation media was developed, which combines the selectivity of a gas diffusion membrane with the substrate specificity of immobilized alcohol oxidase (AOD). The optimization of membrane material and immobilized enzyme was performed using different FIA modes such as dual detection and dual injection. A simple modification of a polypropylene membrane with silicone enabled a very flexible adjustment of the linear range for alcohol detection between 0.0006 and 60% (v v-1). The ethanol content of cultivation media could be determined continuously with a frequency of 120-180 samples per hour with an excellent correlation to gas chromatographic analysis (r = 0.9996). The relative standard deviation for 10 successive injections was lower than 0.5%. Samples (10 µL) were injected into a carrier stream and passed into a perspex gas diffusion unit (52 mm x 1.4 mm x 0.5 mm) containing a composite polypropylene - silicone membrane and maintained at 30°C. The vapor diffused across the membrane into the acceptor stream (1.5 mL min-1) then into the enzyme reactor (2 cm x 2 mm) that contained alcohol oxidase immobilized (by the glutaraldehyde method) on pore glass. Electrochemical detection of the resulting H2O2 was with a platinum electrode at 700 mV vs. Ag - AgCl. The calibration graph was rectilinear from 0.0006 to 60% of ethanol and coefficient of variation (n = 10) was 0.5%. Sample throughput was 180 h-1.
Ethanol Fermentation broth Electrode Electrode Electrode

"Development Of A FIA System With Immobilized Enzymes For Specific Post-column Detection Of Purine Bases And Their Nucleosides Separated By HPLC Column"
J. Biotechnol. 1990 Volume 14, Issue 1 Pages 89-97
Toshio Yao*, Yoshihiro Matsumoto and Tamotsu Wasa

Abstract: A sensitive and highly selective method for the simultaneous determination of purine bases and their nucleosides is proposed. An amperometric flow injection system with the two immobilized enzyme reactors (guanase immobilized reactor and purine nucleoside phosphorylase/xanthine oxidase co-immobilized reactor) is used as the specific post-column detection system of HPLC, to convert compounds separated by a reversed-phase. HPLC column to electroactive species (hydrogen peroxide and uric acid) which can be detected at a flow-through platinum electrode. The proposed detection system is specific for a group of purine bases and purine nucleosides and does not respond for purine nucleotides and pyrimidine bases. The linear determination ranges are from 10 pmol to 5 nmol for four purine bases (hypoxanthine, xanthine, guanine, and adenine) and four purine nucleosides (inosine, xanthosine, guanosine, and adenosine). The detection limits are 1.2-5.5 pmol. Samples were separated by HPLC on a column (25 cm x 4.6 mm) of ODS-A operated at 40°C with a mobile phase (1 mL min-1) of 0.05 M ammonium phosphate buffer solution (pH 2.5). The eluate was mixed with 0.3 M Na2PO4 buffer solution of pH 7.5 (0.5 mL min-) and the mixture was passed through a reactor containing co-immobilized nucleoside phosphorylase - xanthine oxidase. The resulting H2O2 was monitored amperometrically at 0.5 V vs. Ag - AgCl. Calibration graphs were rectilinear form 10 pmol to 5 nmol for the purine bases and purine nucleosides studied and the detection limits were 1.2 to 5.5 pmol. Coefficients of variation (n = 5) were 2.1 to 6.8% for 0.5 nmol of base or nucleoside.
Hypoxanthine Xanthine Guanine Adenine Inosine Xanthosine Guanosine Adenosine HPLC Amperometry Electrode Electrode

"Simultaneous Determination Of Glucose, Ethanol And Lactate In Alcoholic Beverages And Serum By Amperometric Flow Injection Analysis With Immobilized Enzyme Reactors"
J. Biotechnol. 1990 Volume 14, Issue 1 Pages 115-126
Kiyoshi Matsumoto*, Hiroaki Matsubara, Masashi Hamada, Hiroyuki Ukeda and Yutaka Osajima

Abstract: Glucose, ethanol and lactate were determined simultaneously in a flow injection system by using a parallel configuration of immobilized enzyme reactors. Hydrogen peroxide produced was monitored amperometrically at the potential of +0.65 V vs. Ag/AgCl. Linear relations between sensor responses and each species were observed in the ranges of 0.02-10 mM (glucose), 5 x 10^-4-0.1% (v/v) (ethanol) and 0.005-1 mM (lactate) with correlation coefficients larger than 0.999 for each species. The relative standard deviations for 10 successive injections were 1.4, 0.5 and 1.1% for glucose (1 mM), ethanol (5 x 10^-3% (v/v] and lactate (0.05 mM), respectively. Analysis of serum samples was performed with urate-eliminating reactors which were set just before each immobilized enzyme reactor. Interference of ascorbate in a serum sample was completely eliminated by using an ascorbate-eliminating reactor which was set before the sample injection valve. Application of the system to alcoholic beverages and control serum was described and the results were compared with those of free enzymatic, spectrophotometric analysis (F-kit or C-test method). Glucose, ethanol and lactate were determined simultaneously in reactor vessels containing immobilized glucose oxidase, alcohol oxidase and lactate oxidase, respectively in a flow injection analysis (FIA) system. Samples were injected through a 16-way switching valve into the reactor vessels and the resulting H2O2 was measured amperometrically at +0.65 V vs. Ag - AgCl. Urate and ascorbate were removed from serum prior to its analysis using online eliminating-reactors containing uricase - catalase and ascorbate oxidase, respectively. Calibration graphs were rectilinear from 0.02 to 10 mM, 5 x 10^-4 to 0.1%, 5 µM to 1 mM of glucose, ethanol and lactate, respectively with corresponding coefficient of variation (n = 10) of 1.4. 0.5 and 1.1%.
Lactate Ethanol Glucose Beverage Blood Serum Amperometry

"Prerequisites For The Online Control Of Microbial Processes By Flow Injection Analysis"
J. Biotechnol. 1990 Volume 14, Issue 1 Pages 63-70
I. Ogbomo, U. Prinzing* and H. -L. Schmidt

Abstract: Problems associated with the use of biosensors in process control, e.g. difficulties of sterilization and sensor fouling, are shortly displayed, and possibilities to overcome them are outlined. The advantages of flow injection analysis (FIA) are demonstrated and examples for efficient sampling systems connected with this method are reviewed. Special emphasis is given to problem-orientated sample pretreatments, preventing fast inactivation of immobilized enzymes in the analysis system. Examples of problem-orientated sample pretreatment units are given. A proposal for a computer-controlled self-calibrating FIA system is given. A review is presented, with 32 references, on sampling methods for flow injection analysis (FIA) of substances from bioreactors. Emphasis is given to problem-orientated sample pre-treatments, preventing fast activation of immobilized enzymes in the analysis system. Examples of sample pre-treatment units are given and a proposal for a computer-controlled self-calibrating FIA system is given.
Fermentation broth Sensor

"An Automated Spectrophotometric Flow Injection Procedure For The Determination Of Cellulase Activity In Bioreactor Preparations"
J. Biotechnol. 1990 Volume 14, Issue 1 Pages 81-87
P. J. Worsfold*,*, I. R. C. Whiteside, H. F. Pfeiffer and H. Waldhoff

Abstract: Sample (0.6 mL min-1) was injected through a rotary valve into a carrier stream of 0.05 M acetate buffer solution of pH 5 (0.2 mL min-1) until the sample loop (3900 µL) was filled. The loop contained two knitted reactor coils of 200 cm and 300 cm maintained at 50°C. Substrate solution (920 µL ) of 4% Na carboxymethyl cellulose in acetate buffer solution was injected through a second valve, 16 s after which the sample pump was turned off. After incubation the reducing sugar product was reacted with aqueous 5% p-amino-benzoylhydrazide in another reactor coil at 76°C. and the absorbance of the derivative was measured at 410 nm. The calibration graphs were rectilinear up to 0.56 U mL-1 of cellulase with a detection limit of 0.1 U mL-1. Sample throughput was 5 h-1. The method is applicable to other carbohydrases acting on soluble substrates and producing reducing sugars, e.g. amylase, dextranase, xylanase, glucanase, polygalacturonase. A spectrophotometric procedure for the determination of cellulase activity in precipitated bioreactor preparations and culture filtrates is described. It is based on the determination of reducing sugar produced by the action of the enzyme on carboxymethylcellulose. The reducing sugar is derivatized with p-aminobenzoyl-hydrazide and permits a limit of detection of 0.1 U mL-1 cellulase in the presence of background sugar, with a sampling rate of 5 h-1. The method can readily be applied to the determination of any carbohydrase acting on soluble substrates and producing reducing sugars, e.g. amylase, dextranase, xylanase, glucanase and polygalacturonase.
Enzyme, cellulase Spectrophotometry

"Amperometric Bi-enzyme Based Biosensor For The Detection Of Lactose - Characterization And Application"
J. Chem. Technol. Biotechnol. 1990 Volume 49, Issue 3 Pages 255-265
Dorothea Pfeiffer, Edmundas V. Ralis, Alexander Makower, Frieder W. Scheller

Abstract: A 50 µL portion of 5% gelatin solution was mixed with β-galactosidase (I) from Escherichia coli (10.0 iu), Bifidobacterium adolescentes (4.0 iu) and Curvularia inaequalis (10.0 iu) and spread on 1 cm2 of polyethylene support (cf. Scheller et al., DD Patent 150 500, 1979). Additionally, cross-linking using polyvinylisocyanate (40 mL of 5% solution cm-2) was used (cf. Nentwig et al. DD Patent 277 888 4, 1985). The bi-enzyme membrane, obtained by combining a commercial glucose oxidase layer with a I layer between two cellulose membranes, was used to cover Clark-type electrodes which were then used manually or in a continuous-flow system at +600 mV vs. Ag - AgCl. The electrode was used to determine lactose (II) in milk, whey, baby foods, cottage cheese and bovine urine. The calibration graph was rectilinear for 25 mM II; the detection limit was 20 µM. In the analysis of milk, the coefficient of variation (n = 20) was 2%. Results compared well with those obtained by IR spectroscopy and photometry.
Lactose Milk Food Cottage Urine Amperometry Electrode Sensor

"HPLC Analysis Of An Amino Bisphosphonate In Pharmaceutical Formulations Using Post-column Derivatization And Fluorescence Detection"
J. Chromatogr. Sci. 1990 Volume 28, Issue 11 Pages 563-566
Kwong, E.;Chiu, A.M.Y.;McClintock, S.A.;Cotton, M.L.

Abstract: Monosodium 4-amino-1-hydroxybutane-1,1-diphosphonic acid (MK 217) (in tablets or solution) was diluted or extracted with water and injected into an IONPAC NS1 5 µm column (Dionex) which was packed with a neutral macroporous resin that was stable over the entire pH range. The mobile phase (1 mL min-1) was 10 mM phosphate buffer (pH 8.0) - acetonitrile (3:2) containing 10 mM cetyltrimethylammonium bromide, with post-column derivatization (with o-phthalaldehyde and mercaptoethanol) and fluorimetric detection. The calibration graphs were rectilinear from 0.1 to 10 µg mL-1 and 10 µg mL-1 to 1 mg mL-1 with a detection limit of 100 ng. Within-day and between-day coefficient of variation at the 5 µg mL-1 level were 2% and 7%, respectively.
Monosodium 4-amino-1-hydroxybutane-1,1-diphosphonic acid Pharmaceutical HPLC Fluorescence

"Fluorescence Derivatization Approaches For Quantitative High Performance Liquid Chromatography Of Peptides"
J. Controlled Release 1990 Volume 13, Issue 2 Pages 121-128
Gerald R. Rhodes*, Venkata K. Boppana and Marc J. Rubenfield

Abstract: Peptides were isolated from plasma by solid-phase extraction before analysis. For determination of disulfide-containing peptides, the sample was treated with 100 mM borate buffer (pH 8) containing 10 mM dithiothreitol at 50°C for 30 min, followed by 40 mM ammonium 4-chloro-7-sulfobenzofurazan at 60°C for 2 h. After solid-phase extraction, the sample was subjected to HPLC on a 2-mm i.d. column with gradient elution (described) and fluorescence detection at 470 nm (excitation at 380 nm). For determination of arginine-containing peptides, the sample was subjected to HPLC, at 60°C, with gradient elution (described), followed by post-column derivatization with 0.4 M NaOH and 0.05% ninhydrin at 70°C and fluorescence detection at 470 nm (excitation at 390 nm). The method was applied in the analysis of disulfide- and arginine-containing drugs; the calibration graphs were rectilinear for 0.46 to 185 pmol mL-1 of SKF 101926 and for 0.5 to 100 pmol mL-1 of SKF 105494.
Drugs Peptides Blood Plasma HPLC Fluorescence

"Determination Of Some β-endorphin Fragments In Human Plasma By High Performance Liquid Chromatography With Laser-induced Fluorescence Detection"
J. Controlled Release 1990 Volume 13, Issue 2 Pages 129-139
C. M. B. van den Beld**, U. R. Tjaden*, N. J. Reinhoud, D. S. Stegehuis and J. van der Greef

Abstract: Plasma was deproteinized with trichloroacetic acid and applied to a column of Sephadex G-50. The appropriate fraction was concentrated on to a pre-column of Amberlite XAD-2 before analysis by HPLC on a column (10 cm x 3 mm) of C18 material with a mobile phase (0.75 mL min-1) of 0.01 M Na phosphate buffer (pH 2.4) - acetonitrile - 21.5 mM Na 1-octanesulfonate (763:232:5). The eluate was derivatized with 1.65 mM o-phthaldialdehyde - 9.25 mM 2-mercaptoethanol in 0.05 M borate buffer solution (pH 9.4) for 10 s before laser-induced fluorescence detection at 450 or 515 nm (excitation at 351.1, 363.8 or 488 nm). The calibration graph was rectilinear for 1 to 100 ng of des-enkephaline-γ-endorphin; the limit of detection was 0.4 ng mL-1. The method was more senstive than a method involving pre-column derviatization with fluorescein-5-isothiocyanate (described).
β-Endorphin (6-17) Plasma Human HPLC Fluorescence

"Development And Application Of Sample Injector For Flow Injection Analysis"
J. Flow Injection Anal. 1989 Volume 6, Issue 1 Pages 30-36
Wasako Tomoda, Kazuhide Uchida, Kyoko Saji, Kazuaki Fukushima and Shin-ichi Saito

Abstract: The constructed sample injector which has a quartet or synchronized six-valve system for flow injection analysis (diagram presented) has been utilized for assay of guanine deaminase (I). A 50 µL sample is injected and flows with a carrier stream of 0.05 M KH2PO4 - NaOH buffer of 7.4 containing 1.2% of Triton X-100 to react with an enzyme mixture consisting of xanthine oxidase, urate oxidase, catalase and peroxidase in the reaction coil (details given) before further reaction at pH 6.0 with 200 µL of substrate and color reagents of guanine, 3-methylbenzothiazolin-2-one hydrazone and N-ethyl-N-(3-sulfopropyl)-m-anisidine, followed by measurement at 570 nm. The calibration graph is rectilinear from 0.14 to 4.9 iu L-1 of I. For assay of 0.56 and 3.5 iu l-1, coefficient of variation are 1.9 and 0.8%, respectively.
Enzyme, guanine deaminase Spectrophotometry

"A Variable Volume Injector Applied To The Atomic Absorption Determination Of Sodium, Potassium, Calcium And Magnesium In Blood Serum By Flow Injection Analysis"
J. Flow Injection Anal. 1990 Volume 7, Issue 1 Pages 11-18
J.L. BURGUERA*, M. BURGUERA and C. Rivas, M. DE LA GUARDIA, A. SALVADOR and V. CARBONELL

Abstract: Different volume of a single standard solution containing Na, K, Ca and Mg were used to determine the cited metals in serum samples. A simple variable-volume injector (Anal. Chim. Acta, 1990, 234, 253) was used to inject the different volume in order to construct a calibration graph. Diagrams are presented of the injector. The coefficient of variation (n = 8) for the determination of 75, 4, 2 and 0.5 µg of Na, K, Ca and Mg, respectively, were 1.5, 1.2, 0.8 and 1.2%, respectively. Results for 22 µL of standard human serum agreed well with the known values.
Sodium Potassium Calcium Magnesium Serum Human Spectrophotometry

"Flow Injection Analysis For Guanase Activity"
J. Flow Injection Anal. 1990 Volume 7, Issue 2 Pages 113-129
Masako Tomoda, Kazuhide Uchida, Nobuhiko Higuchi, Kyoko Saito

Abstract: The activity of guanine deaminase (I) was determined by a flow method based on the spectrophotometric determination of H2O2 formed by I and coupled enzymes, viz xanthine oxidase and urate oxidase. The FIA system was composed of a series of injection, stopped-flow and merging zone methods (diagrams given). The calibration graph was rectilinear for up to 1.84 iu L-1 of I at 37°C. The coefficient of variation (n = 10) was 1% and the mean recovery was 97%.
Enzyme, guanase Hydrogen peroxide

"Flow Injection Analysis For Rapid Amyloglucosidase Activity Determination"
J. Food Comp. Anal. 1989 Volume 2, Issue 4 Pages 364-370
Clark G. Hartford, David W. Muntz, James V. Evans and Gary T. Blair

Abstract: Modifications were made on the procedure described by Holm (Anal. Abstr., 1987, 49, 5D367) for the determination of glucan 1,4-α-glucosidase (I) which involved an increased sampling rate, replacement of Na2CO3 with sodium borate buffer for a better pH adjustment and elimination of the stopped-flow procedure. The calibration graph was essentially linear between 0.05 and 2.5 diazyme unit (DU) mL-1 (r 0.9996). The sensitivity was 0.1 DU g-1 although I levels in most samples were from 40 to 400 DUu g-1. The coefficient of variation was 1.2% compared with 3.9% for a manual method.
Amyloglucosidase

"Determination Of Free Amino-acids In Cheese By Flow Injection Analysis With An Enzymatic Reactor And Chemiluminescence Detector"
J. Food Sci. 1990 Volume 55, Issue 6 Pages 1555-1558
Puchades, R.;Lemieux, L.;Simard, R.E.

Abstract: L-Amino-acid oxidase solution (3 ml) was added to 0.3 mg of glutaraldehyde-treated glass beads at 4°C and the mixture was set aside for 2.5 h. After washing with water and phosphate buffer solution the beads were packed into a glass column (7.5 cm x 1.7 mm). Freeze-dried extracts of cheese (~30 mg) were sonicated with 0.1 M phosphate buffer solution (pH 7.5) and filtered through a 0.45 µm membrane and a Sep-Pak C18 cartridge before being passed through the immobilized enzyme with 0.1 M phosphate buffer solution (pH 7.5) - 1 mM EDTA as carrier (1 mL min-1). The generated H2O2 was mixed with 1.5 mM luminol solution in 0.1 M Na2CO3 buffer solution (pH 10.5) and 8 mM aqueous K3Fe(CN)6 at 1.5 mL min-1 and the chemiluminescence was detected by a photomultiplier. The log. - log. calibration graphs for L-leucine (I) were rectilinear from 0.025 to 1.0 mM; coefficient of variation (n = 10) were 1.4 and 0.3% for 0.1 and 0.8 mM of I, respectively.
Amino acids, free Food Chemiluminescence

"Continuous-flow Immunoassay For Rapid And Sensitive Detection Of Small Molecules"
J. Immunol. Methods 1990 Volume 135, Issue 1-2 Pages 191-197
Anne W. Kusterbeck, Gregory A. Wemhoff, Paul T. Charles, Doyle A. Yeager, Reinhard Bredehorst, Carl-Wilhelm Vogel and Frances S. Ligler,*

Abstract: The assay is based on the binding of labelled antigen to an immobilized antibody with subsequent displacement of the labelled antigen when antigen is present in the buffer flow. The hapten 2,4-dinitrophenol (DNP) as DNP-lysine was used as model antigen with either 125I-labelled DNP-insulin or fluorescein-labelled DNP-insulin as labelled antigen. The radiolabelled antigen was used to establish assay conditions. Anti-DNP antibody was immobilized on tresyl chloride-activated Sepharose 4B and, after immobilization, the available antigen-binding sites were occupied with labelled antigen and the gel was packed into 6-mm i.d. columns. Borate-buffered saline (pH 8.2) was continuously flushed through the column. Sample (200 µL) was injected into the buffer flow and the displaced labelled antigen to the effluent was monitored fluorimetrically at 515 nm (excitation at 492 nm) or by collection of fractions followed by liquid scintillation counting. The calibration graphs were rectilinear from 570 to 4600 nM-DNP and down to 140 nM could be detected using a 200 µL column.
Immunoassay

"Determination Of Neomycin In Milk By Reversed-phase Ion-pairing Liquid Chromatography"
J. Liq. Chromatogr. Relat. Technol. 1989 Volume 12, Issue 8 Pages 1497-1515
Badar Shaikh; Jean Jackson

Abstract: Milk was skimmed and a 1 mL portion was vortex-mixed with 20% trichloroacetic acid solution (100 µL) and centrifuged at 4000 rpm and 4°C for 30 min. A 180 µL portion of the supernatant liquid was vortex-mixed with 20 µL of 1 M Na pentanesulfonate - 0.07 M acetic acid, and a 25 µL aliquot of the mixture was analyzed by HPLC on a column (15 cm x 4.6 mm) fitted with a guard column (2 cm x 4.6 mm) both containing Supelcosil LC-8-DB (5 µm) at 32.5°C. Post-column derivatization was at 33°C in a reaction coil with phthalaldehyde. The ion-pairing mobile phase contained 0.01 M pentanesulfonate, 0.056 M Na2SO4, 7 mM acetic acid and 1.5% methanol and fluorimetric detection was at 455 nm (excitation at 340 nm). A calibration graph (peak heights) was rectilinear from 0.15 to 12 µg mL-1 of neomycin in whole milk, and overall recovery was 94%, with coefficient of variation of 6.8%. The method was applied to monitor neomycin in milk after intramuscular injection at 10 mg kg-1.
Neomycin B Milk Whole Skimmed HPLC Fluorescence

"Evaluation Of Flow Injection Sample To Standard Addition Method For The Inductively Coupled Plasma Mass Spectrometric Determination Of Aluminum In Biological Tissues"
J. Mass Spectrom. 1996 Volume 31, Issue 4 Pages 427-432
A. G. Coedo*, M. T. Dorado, J. Ruiz, M. Escudero, J. C. Rubio

Abstract: Tissues were minced, dried and powdered. Portions (0.5 g) were oxidized with 4 mL HNO3 in a microwave apparatus, with a 7-step heating programme. The solution was evaporated almost to dryness, mixed with a solution containing 1 µg Sc(III) (internal standard to compensate for plasma and ion signal instability) and diluted to 25 mL with 0.1% HNO3. Portions (0.5 ml) of this solution were injected into the carrier (2.8 ml/min) containing an Al(III) standard of 20 ng/ml and 40 ng/nl of Sc(III) in 0.1% HNO3 and this was followed by the injection of 0.5 mL of a digestion blank. The injection valve was located a few cm away from the cross-flow nebulizer and the ions 27Al and 45Sc were measured. The sample concentration then corresponded to the difference between the signals for the sample (maximum) and the blank (minimum). The method has the advantages of requiring less sample, being quicker and minimizing salt deposition on the sample and skimmer cones. Results for reference materials were similar to those obtained by conventional standard additions. Recovery of 0.5-10 ppm Al(III) was close to 100%. The detection limit was 10 ppb.
Aluminum(III) Biological tissue Mass spectrometry Sample preparation

"An Automated Microtechnique For Selenium Determination In Human Body Fluids By Flow Injection Hydride Atomic Absorption Spectrometry"
J. Trace Elem. Electrolytes Health Dis. 1990 Volume 4, Issue 1 Pages 41-48
Negretti de Bratter VE, Bratter P, Tomiak A

Abstract: The automation of a flow injection system for the hydride generation of selenium and its subsequent determination by atomic absorption spectrometry (FI-HAAS) is described. Pre-treatment of the sample and the details of the automated equipment are reviewed. For the FI-HAAS selenium analysis a volume of 350 µL of acid-digested sample solution is injected. The online generated hydride is delivery by the gas-liquid separator and is transported together with an Ar stream to the heated quartz cell for the atomic absorption determination. The absolute detection limit is 35 pg Se; the relative detection limit 0.10 µg/L Se. The absolute determination limit in real biological samples is 110 pg Se; the relative detection limit 0.31 µg/L Se. The accuracy of the method was evaluated via analysis of certified standard reference materials. Quality control was made by comparing FI-HAAS and instrumental neutron activation analysis (INAA), as an independent analytical method. Two acid-digestion procedures (in open vessels at atmospheric pressure and bomb-digestion in pressure vessels) were experimentally tested. To determine the effectiveness of the selenium reduction and the completeness of the selenium hydride formation a parallel selenium determination was carried out by means of ICP-AES and FI-HAAS analysis. FI-HAAS was applied for blood serum analysis of children undergoing long-term total parenteral nutrition, as well as of persons with high dietary selenium intake, and for human milk analysis. Human serum or milk (150 µL) is digested overnight with 1 mL of concentrated HNO3, a further 1 mL of HNO3 is added, and the sample is ashed for 1 h at 170°C. After addition of 100 µL of H2SO4 and 50 µL of HClO4, the sample is ashed for a further 1.5 h. Alternatively bomb-digestion is performed for 5 h at 160°C. The digest is diluted to 3 mL with 5 M HCl and heated at 95°C for 30 min for reduction of Se(VI) to Se(IV). A 350 µL portion of this solution is injected into a water carrier stream (2.2 mL min-1) that is subsequently mixed with streams of HCl (2.2 mL min-1) and alkaline 3% NaBH4 (0.44 mL min-1). The reaction mixture is passed into a gas - liquid separator and the H2Se formed is swept by Ar (0.3 l min-1) into a heated silica tube, where it is atomized at 900°C for detection of Se at 196.0 nm. Calibration graphs are rectilinear for 0.87 to 8.7 ng of Se injected and the limit of detection is 0.1 µg l-1. Results for four biological standard reference materials (including NBS Bovine Serum and Oyster Tissue) agreed well with certified values. Results for Se in human serum or milk generally agreed well with those obtained by instrumental NAA.
Selenium Serum Human Milk NIST 1566 NIST 1598 Sample preparation Spectrophotometry

"Studies On Ion Selective Electrodes. 1. Automatic Data Acquisition System For Potentiometric Measurements"
Kem. Kemi 1978 Volume 5, Issue 10 Pages 460-463
Virtanen, R.

Abstract: An automatic data acquisition system was constructed for simultaneous measurements with up to 5 ion-selective electrodes. The potentials of the different electrodes are multiplexed, converted into digital form, and collected on magnetic tape with the aid of an off-line computer terminal. A high impedance amplifier (>1012 .OMEGA.) is located in each channel before the multiplexer, and a digital pH meter serves as the converter. With the control unit the operator can start and stop an experiment, choose the time interval between subsequent measuring cycles (from 0.5-1.5 s, depending on the number of channels, to 99 s), and choose the number of channels (1-5). Manual control can be used to choose any single channel to be followed. Collected data can later be processed by a computer. Examples are given of the use of the system in automatic calibration and long-term testing of electrode stability and in quant. flow injection analysis of multi-ion solutions with several electrodes.
Electrode Potentiometry

"Instrumentation Based On Microcomputers. 5. A Computer-operated Flow Injection Analyser"
Lab. Microcomput. 1989 Volume 8, Issue 2 Pages 44-52
Malcolme Lawes, D.J.;Pasquini, C.;Wong, K.H.

Abstract: Improvements in the instrument described previously (Anal. Abstr., 1988, 50, 9J17) and its control system are described. The apparatus was applied in the determination of NO2-, NO3-, NH4+ and PO43- in drinking water by conventional colorimetric reactions. Respective calibration graphs were rectilinear up to 0.1, 50, 0.12 and 20 ppm with limits of detection of 4, 30, 5 and 21 ppb. The coefficient of variation (n = 10) were generally 3%.
Nitrite Nitrate Phosphate Ammonium Nitrogen Water Spectrophotometry

"Automated Colorimetric Method For Determination Of Chlorine In Geological Materials Using Flow Injection Analysis Technique"
Lab. Rob. Autom. 1990 Volume 2, Issue 2 Pages 83-88
Chan, C.C.Y.

Abstract: Powdered rock sample (0.15 g) was fused with LiBO2 at 860°C and the melt was dissolved in 9% HNO3. After dilution to 15 ml, the solution was mixed with 0.5% Hg(SCN)2 and 0.5 M Fe(NO3) in a carrier flow of 6% HNO3 and the absorbance was measured at 480 nm. The method was applied to 22 geochemical reference samples and gave coefficient of variation from 0.7 to 9.3%; the results agreed closely with those obtained in the literature. The limit of determination was 15 ppm in rock and calibration covered 50 to 500 ppm.
Chlorine Geological Sample preparation Spectrophotometry

"Flow Injection In-valve Solid Phase Extraction Spectrophotometric Determination Of Uranium In Geological Samples"
Lab. Rob. Autom. 1998 Volume 10, Issue 1 Pages 25-31
Kate Grudpan *, Jaroon Jakmunee, Ponlayuth Sooksamiti

Abstract: Flow injection analysis (FIA) system incorporating in-valve solid phase extraction microcolumn for online separation and pre-concentration using a new resin, U/TEVA-Spec, is proposed for the spectrophotometric determination of U in geological samples using 4-(2-pyridylazo)resorcinol (PAR) as a color agent. Optimization of the condition involved in the system was studied. Possibility of a single standard calibration is discussed.
Uranium Geological Spectrophotometry

"Application Of Sequential-injection Analysis As Process Analyzers"
Lab. Rob. Autom. 1998 Volume 10, Issue 6 Pages 325-337
R. E. Taljaard, J. F. van Staden

Abstract: The development of sequential-injection analysis (SIA) from its mother technique flow injection analysis (FIA) is reviewed. A short historical background is given as well as discussions on the basic principles and operational parameters governing the design of an SLA system. Single-, double-, and multizone systems are described together with more complicated systems including calibration, dilution, extraction, dialysis, titrations, separation, pre-concentration, and systems incorporating mixing chambers.
d-Lactic acid Spectrophotometry

"Determination Of Proteases By Flow Injection Analysis"
Nippon Shokuhin Kagaku Kogaku Kaishi 1990 Volume 37, Issue 1 Pages 55-60
Tomoko ETO, Kiyoshi MATSUMOTO, Yutaka OSAJIMA

Abstract: A flow injection analysis system equipped with an automatic filtration unit was investigated for the determination of proteolytic activity with casein. Protein digestion and the addition of CCl3COOH were performed by batch procedure before injection of the digests into the flow system. The resulting Folin-positive digests were filtered automatically and injected into the flow system. The digests were detected spectrophotometrically by reaction with Folin-Ciocalteu reagent. The sampling frequency was 20 h-1 when 20 µL samples were used. The calibration graph of tyrosine was rectilinear from 10 to 50 µg mL-1.
Enzyme, protease Tyrosine Enzyme, activity Sample preparation Spectrophotometry

"FIA Spectrophotometric Assay Of N-acetylcysteine By O-phthalaldehyde Derivatization"
Pharmazie 1990 Volume 45, Issue 10 Pages 745-747
Medina Hernandez, M.J.;Garcia Alvarez Coque, M.C.;Bonet Domingo, E.;Villanueva Camanas, R.M.

Abstract: A flow injection spectrophotometric procedure is proposed for the determination of N-acetylcysteine (NAC). The procedure is based on the rapid reaction of the thiol group with o-phthalaldehyde and isoleucine at pH 9.5 to give an 1-alkylthio-2-alkyl-substituted isoindole which shows maximum absorbance at 335 nm. The linear dynamic range is 16-160 µg/ml, with a 0.6% relative standard deviation for 100 µg/ml. The sampling rate is 126 samples/h. The method is applied successfully to the evaluation of NAC in commercial formulations. Portions (120 µL) of standard N-acetylcysteine (I) or aqueous dilution of I formulations were injected into a flowing stream of a mixture of borate buffer (pH 9.5) - ethanolic 50 mM 2-phthalaldehyde (4:1) and mixed in a 2.2 m coil; 10 mM isoleucine in 1 M HCl was introduced at a T-junction and further mixed in an 80-cm coil. The absorbances were measured at 335 nm. The calibration graph was rectilinear for 16 to 160 µg mL-1. The coefficient of variation for a 100 µg mL-1 of I was 0.6%. Results for four formulations agreed within 7% of the labelled values and also agreed with the results by batchwise analysis with the same method, iodimetric titration and oxidation with Fe(III) in the presence of 1,10-phenanthroline.
N-acetylcysteine Pharmaceutical Spectrophotometry

"Determination Of Indium In Natural Waters By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
Proc. Indian Acad. Sci. 1998 Volume 107, Issue 4 Pages 359-366
DIA SOTTO ALIBO, HIROSHI AMAKAWA and YOSHIYUKI NOZAKI

Abstract: Two methods were developed to measure In in natural waters by flow injection inductively coupled plasma mass spectrometry (ICP-MS). One is the isotope dilution technique using an 113In enriched spike and the other utilizes natural Y present in the sample as an internal standard In the former, optimization of the 113In spike to minimize error is often difficult for samples in which In concentrations are variable, whereas in the latter method, a sep. determination of Y in the sample is necessary and hence more sample is required. Using ≈1 L of a water sample, 200-fold pre-concentration of In was performed by solvent extraction and back extraction technique and then introduced into the ICPMS to measure the 113In/115In or 115In/89Y ratios. The detection limits were 0.01-0.02 pmol kg-1 for both methods. Application of the methods to seawater samples yielded the concentrations of 0.06-0.15 for the Pacific and 0.6-1.5 pmol kg-1 for the Atlantic. The large inter-oceanic variation of In best resembles that of Al amongst the 3B group of elements in the periodic table. River and estuarine samples gave a more variable range of concentrations of 0.01-15 pmol kg-1. Most of the In supplied by rivers is removed by scavenging in the estuarine mixing zone, suggesting that the fluvial input of In to the ocean is small.
Indium River Estuarine Sea Mass spectrometry Mass spectrometry Sample preparation

"Design Of Flow Injection Manifolds To Give The Best Detection Limits For Methods Involving Online Chemical Derivatization. 2. The Spectrophotometric Determination Of Chloride"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 179-189
Tyson, J.F.;Fogg, A.G.;Wang, X.

Abstract: A double-line manifold (described and illustrated) for the spectrophotometric determination of Cl- was developed, incorporating pulse dampers, a packed-bed reactor and a delay coil for baseline noise reduction and removal of valve-switching effects. Optimum conditions, determined from an offline experiment, agreed with predicted ones. The effects of flow rate ratio and injection volume were investigated. A calibration graph of absorbance (at 480 nm) vs. concentration. was rectilinear from 4.5 ppb (detection limit) to 2 ppm.
Chloride Spectrophotometry

"Online Trace Metal Enrichment In Flow Injection Atomic Absorption Spectrometry"
Quim. Anal. 1989 Volume 8, Issue 2 Pages 159-170
Devi, S.;Habib, K.A.J.;Townshend, A.

Abstract: Aqueous samples containing Cu2+, Cd2+, Mg2+, Zn2+, Pb2+ and Hg2+ were pre-concentrated on a mini-column of 8-hydroxyquinoline-5-sulfonic acid immobilized on to controlled-pore glass and eluted with HNO3 or HCl (depending on the metal to be analyzed) directly into a nebulizer for AAS analysis. Calibration graphs were rectilinear from 0 to 100, 100 to 1000, 20 to 220, 10 to 100, 10 to 300 and 20 to 2000 ng mL-1 of Cd2+, Pb2+, Zn2+, Mg2+, Cu2+ and Hg2+, respectively; detection limits ranged from 0.5 ng mL-1 (for Cu) to 25 ng mL-1 (for Hg). . The coefficient of variation ranged from 1.1 to 2.9% (n = 4). Aqueous samples containing Cu2+, Cd2+, Mg2+, Zn2+, Pb2+ and Hg2+ were pre-concentrated on a mini-column of 8-hydroxyquinoline-5-sulfonic acid immobilized on to controlled-pore glass and eluted with HNO3 or HCl (depending on the metal to be analyzed) directly into a nebulizer for AAS analysis. Calibration graphs were rectilinear from 0 to 100, 100 to 1000, 20 to 220, 10 to 100, 10 to 300 and 20 to 2000 ng mL-1 of Cd2+, Pb2+, Zn2+, Mg2+, Cu2+ and Hg2+, respectively; detection limits ranged from 0.5 ng mL-1 (for Cu) to 25 ng mL-1 (for Hg). . The coefficient of variation ranged from 1.1 to 2.9% (n = 4).
Copper Cadmium Magnesium Zinc Lead Mercury Spectrophotometry

"Analysis Of Peptides And Proteins By Capillary Electrophoresis - Mass Spectrometry Using Acidic Buffers And Coated Capillaries"
Rapid Commun. Mass Spectrom. 1991 Volume 5, Issue 10 Pages 484-490
P. Thibault, C. Paris, S. Pleasance, R. M. Caprioli

Abstract: A newly built capillary electrophoresis - MS interface involving ionspray ionization and a coaxial capillary arrangement was used to separate and determine peptides, tryptic fragments and proteins of mol. wt. up to 80 kDa. The interface provides an efficient means of optimizing and calibrating the mass spectrometer by using flow injection analysis, and minimizes peak broadening. Capillary electrophoretic separation of proteins by using a low-pH buffer and a capillary coated with cationic polymer gave better sensitivity and efficiency as compared with similar analyzes at high pH with uncoated capillaries. Pre-formed cationic species are thereby available for MS detection, and the analysis of proteins with high isoelectric points is possible even at low pH. The ability to conduct electrophoresis of globular proteins under acidic conditions permits conformational changes to be monitored in terms of variations in migration times and concurrent changes in the multi-charged ion envelopes. Relatively small amounts of sample are required and successful compromises between scan speed, scan range and separation efficiency are achieved.
Peptides Proteins Electrophoresis Mass spectrometry

"Determination Of Copper(II) By Flow Injection Analysis"
Rev. Chim. 1990 Volume 41, Issue 4 Pages 361-365
Danet, A.F.;Mircea, V.

Abstract: Details are given of a flow injection analysis system for the determination of Cu(II) with an emphasis on the injection valve (illustrated). Sample solution (200 µL) was injected into a reagent stream (2.5 min-1) of aqueous 1 M NH3 solution and passed through a 60-cm reaction coil before the absorbance of the solution was measured at 630 nm. The calibration graph was rectilinear from 50 to >1600 ppm of Cu(II). The limit of detection was 50 ppm and the coefficient of variation (n = 14) was 0.8% at 800 ppm of Cu(II). Sample throughput was 75 to 300 h-1, depending on Cu concentration.
Copper(II)

"Automatic Precipitation In Flow Injection Analysis With Online Dialysis - Indirect Determination Of Sulfate By Measurement Of The Unprecipitated, Excess Barium In The Dialysate Stream Of The Flow System"
South Afr. J. Chem. 1990 Volume 43, Issue 3-4 Pages 78-82
van Staden, J.F.; van Rensburg, A

Abstract: The method is based on a combination of the formation of a continuous solid - liquid interface (precipitation) and a continuous liquid - liquid interface (dialysis). Sulfate from a 30 µL sample is precipitated turbidimetrically with an excess of BaCl2 to form a suspended ppt. of BaSO4. Excess Ba2+ is transported with the carrier stream to the donor channel of the dialyser where it dialyses to the detector channel. The dialysate of Ba reacts with methylthymol blue to form a complex which is measured spectrophotometrically at 608 nm. The pH was kept relatively high with NaOH. The proposed flow injection procedure is suitable for the indirect determination of SO42- at a sampling rate of 60 samples h-1 with a coefficient of variation of 1.4%. The calibration graph was rectilinear in the range 100 to 1000 mg L-1 and the recovery was 98.8 to 100.5%.
Sulfate Turbidimetry

"Program Based On The Pattern-search Method: Application To Periodate Determination Using Flow Injection Analysis And Chemiluminescence Detection"
Trends Anal. Chem. 1988 Volume 7, Issue 10 Pages 366-370
Emmanuel M. Papamichael and Nicholaos P. Evmiridis

Abstract: The BASIC program presented, which requires 4K of memory, permits any multi-parameter function with a discontinuous derivative to be fitted. Its use is illustrated by the fitting of a chosen model function to the non-rectilinear calibration graph in the flow injection chemiluminescence determination of IO4- described previously [Evmiridis, Analyst (London), 1987, 112, 825].
Periodate Chemiluminescence

"Comparison Of Digoxin Analysis By High Performance Liquid Chromatography - Post-column Derivatization And Fluorescence-polarization Immunoassay"
Xenobiotica 1990 Volume 20, Issue 6 Pages 635-643
L. Embree and K. M. McErlane

Abstract: The method described previously (J. Chromatogr., 1989, 496, 321) was compared with the Abbott TDx method. The r value between the two methods for digoxin added to drug-free serum was 0.9897 (n = 7). However, serum from digitalized patients showed higher digoxin levels by the TDx method, probably owing to cross-reactivity of metabolites. Cross-reactivity of the TDx method towards endogenous material in the serum of certain patient groups was an even greater problem. The HPLC method (loc. cit.) gave complete resolution of digoxin. The calibration graph for this method was rectilinear for 0.5 to 3.3 ng mL-1 of digoxin in a 3 mL serum sample, with a mean coefficient of variation of 5.6% and a detection limit of 0.5 ng injected.
Digoxin Serum Human HPLC Immunoassay Fluorescence

"Single-standard FIA Gradient Calibration Technique In Catalytic Kinetic Spectrometric Determination"
Yingyong Huaxue 1991 Volume 8, Issue 2 Pages 75-77
Yang Jiannan, Zang Shuliang, Jiang Yufen, Liu Gang

Abstract: In combination with microprocessor, by using FIA stopped-flow technique and gradient calibration, a single standard catalytic kinetic spectrophotometric method is described. The method is simply operated and good reproducible. It has been used in determination of trace Mn(II) in natural water. The results were in accordance with those obtained using Otto-Rentsch-Werner method in literature.
Manganese Environmental Spectrophotometry

"Clenbuterol Residue Analysis By HPLC - HPTLC In Urine And Animal Tissues"
Z. Lebensm. Unters. Forsch. 1989 Volume 189, Issue 2 Pages 128-131
Jean-Marie Degroodt, Brigitte Wyhowski de Bukanski, Hedwig Beernaert and Dirk Courtheyn

Abstract: Tissue samples were digested with subtilisin A at 55°C for 1 h in 0.2 M Tris buffer of pH 8 containing 0.1 M CaCl2. The mixture was centrifuged, the solid was washed with more buffer and the supernatant solution were combined. This solution, or a diluted urine sample, was adjusted to pH 10 with NaOH and applied to a Chem Elut CE 1020 column; after 15 min, clenbuterol was eluted with hexane (three portions) and extracted from the eluate into 0.01 M HCl. The resulting solution (100 µL) was analyzed by HPLC on a column (25 cm x 4 mm) of LiChrosorb RP-8 (10 µm), with 0.01 M Na acetate (pH 3.5) - acetonitrile (3:7) as mobile phase (1 mL min-1) and post-column derivatization by adding NaNO2 - HCl (cooled in ice), ammonium sulfamate and N-(1-naphthyl)ethylenediamine with product determination at 500 nm. The calibration range for clenbuterol was 5 to 100 ng mL-1 and the detection limit was 2 ng. Recoveries ranged from 70 to 73% for tissues and from 85 to 90% for urine. The results were confirmed by high performance TLC.
Clenbuterol Urine Biological tissue HPLC

"Fitting Of Calibration Graphs With Automated Creatinine Determination As Example"
Zentralbl. Pharm., Pharmakother. Lab. Diagn. 1986 Volume 125, Issue 5 Pages 273-278
Krause, H.;Egger, E.

Abstract: Creatinine solution (5 to 50 mg l-1, in 10 equal steps) were analyzed in a flow injection apparatus and the detector response was obtained in mm peak heights on a chart recorder. A pocket computer was used to calculate the constants, assuming the calibration graph to be a polynomial of the first, second or third order and involving all 10 points. The constants were then used to recalculate the concentration. of the 10 solution, and these values were compared with the known values by using a best fit function. The best results were given by the third-order polynomial, and the worst by a linear (first-order) polynomial. A method is also given for determining the optimum number of steps in calibration (in the present instance 5 or 6).
Creatinine

"Oxygen And Glucose Optical Biosensors Based On Phosphorescence Quenching Of Metalloporphyrins"
J. Anal. Chem. 1990 Volume 45, Issue 7 Pages 1441-1445
Papkovskii, D.B.;Savitskii, A.P.;Yaropolov, A.I.

Abstract: Serum (80 µL) was injected into a reagent stream (5 mL min-1) of phosphate buffer (pH 7) containing 0.1% of Tween 20 and 0.5 µM-Pd(II) - coproporphyrin I complex and passed through a column (7 cm x 5 mm) of glucose oxidase immobilized on glass beads. Detection was at 650 to 750 nm (excitation was at 350 to 550 nm). The sample throughput was 20 h-1. The calibration graph was rectilinear from 2 to 300 mM glucose and the coefficient of variation were 3% (n = 5).
Metalloporphyrins Phosphorescence Sensor

"Simultaneous Determination Of Rifampicin And Isoniazid By Continuous-flow Chemiluminescence With Artificial Neural Network Calibration"
Anal. Bioanal. Chem. 2005 Volume 383, Issue 5 Pages 817-824
Baoxin Li, Yuezhen He, Jiagen Lv and Zhujun Zhang

Abstract: In this paper a continuous-flow chemiluminescence (CL) system with artificial neural network calibration is proposed for simultaneous determination of rifampicin and isoniazid. This method is based on the different kinetic spectra of the analytes in their CL reaction with alkaline N-bromosuccinimide as oxidant. The CL intensity was measured and recorded every second from 1 to 300 s. The data obtained were processed chemometrically by use of an artificial neural network. The experimental calibration set was 20 sample solutions. The relative standard errors of prediction for both analytes were approximately 5%. The proposed method was successfully applied to the simultaneous determination of rifampicin and isoniazid in a combined pharmaceutical formulation.
Isoniazid Rifampicin Pharmaceutical Chemiluminescence

"Flow System From Analytical Calibration By The Integrated Method"
Instrum. Sci. Technol. 2002 Volume 30, Issue 3 Pages 251-266
Pawe&#; Koscielniak, Joanna Kozak, Ma&#;gorzata Herman

Abstract: The flow system has been designed for the purpose of performing analytical determinations according to the integrated calibration method. The system is equipped with a fully rotary valve which serves in preparation of the set of standard solutions from a single stock solution. A standard is exposed to measurements in two forms: by itself, and as a mixture with a sample. Each of the two solutions is able to be propelled to the detector at two different flow rates. As a consequence, the measurement information gathered during a single calibration run permits calculation of several estimations of an analytical result, in both the interpolative and extrapolative manner. Since some estimations are independent of each other, the final result is reliable in terms of accuracy, more than if using a conventional calibration approach. Owing to the instrumental simplicity and analytical efficiency, the system is expected to be useful for routine analysis.

"Study Of The Voltammetric Behaviour Of Metam And Its Application To An Amperometric Flow System"
Anal. Bioanal. Chem. 2005 Volume 383, Issue 5 Pages 880-885
M. F&aacute;tima Barroso, Paula Pa&iacute;ga, M. Carmo V. F. Vaz, Cristina Delerue-Matos

Abstract: The electrochemical behavior of the pesticide metam (MT) at a glassy carbon working electrode (GCE) and at a hanging mercury drop electrode (HMDE) was investigated. Different voltammetric techniques, including cyclic voltammetry (CV) and square wave voltammetry (SWV), were used. An anodic peak (independent of pH) at +1.46 V vs AgCl/Ag was observed in MT aqueous solution using the GCE. SWV calibration curves were plotted under optimized conditions (pH 2.5 and frequency 50 Hz), which showed a linear response for 17-29 mg L-1. Electrochemical reduction was also explored, using the HMDE. A well defined cathodic peak was recorded at -0.72 V vs AgCl/Ag, dependent on pH. After optimizing the operating conditions (pH 10.1, frequency 150 Hz, potential deposition -0.20 V for 10 s), calibration curves was measured in the concentration range 2.5 x 10^-1 to 1.0 mg L-1 using SWV. The electrochemical behavior of this compound facilitated the development of a flow injection analysis (FIA) system with amperometric detection for the quantification of MT in commercial formulations and spiked water samples. An assessment of the optimal FIA conditions indicated that the best analytical results were obtained at a potential of +1.30 V, an injection volume of 207 µL and an overall flow rate of 2.4 mL min-1. Real samples were analyzed via calibration curves over the concentration range 1.3 x 10^-2 to 1.3 mg L-1. Recoveries from the real samples (spiked waters and commercial formulations) were between 97.4 and 105.5%. The precision of the proposed method was evaluated by assessing the relative standard deviation (RSD %) of ten consecutive determinations of one sample (1.0 mg L-1), and the value obtained was 1.5%.
Methylcarbamodithioic acid Environmental Electrode Electrode Electrode Voltammetry Voltammetry Electrochemical analysis Amperometry

"Determination Of Copper In Powdered Chocolate Samples By Slurry-sampling Flame Atomic-absorption Spectrometry"
Anal. Bioanal. Chem. 2005 Volume 382, Issue 4 Pages 1099-1102
Walter N. L. dos Santos, Erik G. P. da Silva, Marcelo S. Fernandes, Rennan G. O. Araujo, Ant&ocirc;nio C. S. Costa, M. G. R. Vale, S&eagrave;rgio L. C. Ferreira

Abstract: Chocolate is a complex sample with a high content of organic compounds and its analysis generally involves digestion procedures that might include the risk of losses and/or contamination. The determination of copper in chocolate is important because copper compounds are extensively used as fungicides in the farming of cocoa. In this paper, a slurry-sampling flame atomic-absorption spectrometric method is proposed for determination of copper in powdered chocolate samples. Optimization was carried out using univariate methodology involving the variables nature and concentration of the acid solution for slurry preparation, sonication time, and sample mass. The recommended conditions include a sample mass of 0.2 g, 2.0 mol L-1 hydrochloric acid solution, and a sonication time of 15 min. The calibration curve was prepared using aqueous copper standards in 2.0 mol L-1 hydrochloric acid. This method allowed determination of copper in chocolate with a detection limit of 0.4 µg g-1 and precision, expressed as relative standard deviation (RSD), of 2.5% (n=10) for a copper content of approximately 30 µg g-1, using a chocolate mass of 0.2 g. The accuracy was confirmed by analyzing the certified reference materials NIST SRM 1568a rice flour and NIES CRM 10-b rice flour. The proposed method was used for determination of copper in three powdered chocolate samples, the copper content of which varied between 26.6 and 31.5 µg g-1. The results showed no significant differences with those obtained after complete digestion, using a t-test for comparison.
Copper Food Spectrophotometry

"Use Of Multivariate Curve Resolution For Determination Of Chromium In Tanning Samples Using Sequential Injection Analysis"
Anal. Bioanal. Chem. 2005 Volume 382, Issue 2 Pages 328-334
V. G&oacute;mez, M. P. Callao

Abstract: We report a method for determining total chromium in tanning samples using sequential injection analysis (SIA) with a diode-array spectrophotometric detector. With a suitable analytical sequence CrO42- is converted to Cr2O72- inside the tubes of the SIA system, after total oxidation of chromium(III). A data matrix is obtained and analyzed by several chemometric techniques based on multivariate analysis: principal components analysis, simple-to-use interactive self-modelling mixture analysis, and multivariate curve resolution-alternating least-squares. We studied several samples from different stages of a tanning process. Two of these samples were easily oxidized but the others needed more extreme conditions. The analytical sequence prepared, which was based on obtaining a pH gradient and used H2SO4 as reagent, is valid and independent of the level of oxidation needed for the sample. We established a calibration model and evaluated the figures of merit. In some samples we found interferents. With this method the amounts of chromium in each sample were quantified and the results were statistically similar to those obtained by use of the reference method, atomic absorption spectrometry.
Chromium, total Chromium(III) Spectrophotometry