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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Analytical Communications

  • Publisher: Royal Society of Chemistry
  • FAD Code: ANCO
  • CODEN: ANCOFE
  • ISSN: 1359-7337
  • Abbreviation: Anal. Commun.
  • DOI Prefix: 10.1039
  • Other Name(s): Proceedings of the Society for Analytical Chemistry (From 1964 v1-8),Proceedings of the Analytical Division of the RSC (as of 1972 v9-11),Proceedings of the Analytical Division of the Chemical Society (as of 1975 v12-18),Analytical Proceedings (as of 1980
  • Language: English
  • Comments: Fulltext from 1964 V1

Citations 30

"Isodispersion Curves In Flow Injection Analysis"
Anal. Commun. 1999 Volume 36, Issue 11-12 Pages 407-408
Danut-Ionel Vaireanu, Peter R. Fielden and Richard D. Snook

Abstract: This paper describes experimental equations that relate the dispersion coefficient to the geometry and hydrodynamic parameters of a flow injection system. Data are presented as isodispersion curves (similar to isothermal, isobar or isochore representations). The results present a correlated overview, which makes theoretical evaluation of the dispersion coefficient simple. Geometric and operational parameters for a flow injection system can be established when the dispersion is to be maintained within certain limits. The parameters addressed in this study are: tube length (100-1200 mm); tube diameter (0.3-0.8 mm); injected volume (93 µl); and volumetric flow rate (0.75-2.0 mL min-1).

"Similarity And Scaling In Flow Injection Analysis"
Anal. Commun. 1999 Volume 36, Issue 11-12 Pages 403-405
Danut-Ionel Vaireanu, Peter R. Fielden and Richard D. Snook

Abstract: In this paper scaling laws and similarity conditions are applied to the problem of scaling the size of flow injection apparatus with reference to contemporary research in miniaturisation of analytical instrumentation. Equations are presented which define the similarity conditions for two flow injection (FI) analysis systems allowing systems to be scaled up or down with respect to a reference flow injection analysis system. Novel partial similarity coefficients with respect to the dispersion coefficient, residence time and dispersion factor are defined and a similarity coefficient based on the partial similarity coefficients is introduced to assess and compare the degree of similarity of two or more FI systems.

"A Redox Hydrogel Integrated PQQ-glucose Dehydrogenase Based Glucose Electrode"
Anal. Commun. 1999 Volume 36, Issue 11-12 Pages 395-398
M. Alkasrawi, I. C. Popescu, V. Laurinavicius, B. Mattiasson and E. Csöregi

Abstract: The present work describes the design and characteristics of a glucose electrode based on a newly isolated and purified, oxygen-independent, pyrrole quinoline quinone glucose dehydrogenase (PQQ-GDH) integrated in a redox hydrogel (poly(1-vinylimidazole) complexed with Os(4-4-dimethylbipyridine)(2)Cl) using poly(ethylene glycol)diglycidyl ether (PEGDGE) as a crosslinker. The influence of the buffers nature and the presence of PQQ and Ca2+ ions on the enzyme stability were considered. The characteristics of the optimal electrode design were compared to those obtained for similarly prepared, glucose oxidase based electrodes. The optimal electrode configuration inserted in a single manifold flow injection system, was characterized by a linear range up to 100 µM, a sensitivity of 5.9 mA M-1 cm-2, and a detection limit of 5 µM (calculated as three times the signal-to-noise ratio).
Membrane

"Plant Tissue-based Chemiluminescence Flow Biosensor For Oxalate"
Anal. Commun. 1999 Volume 36, Issue 9-10 Pages 337-339
Wei Qin, Zhujun Zhang, Youyuan Peng and Baoxin Li

Abstract: A novel plant tissue-based chemiluminescence (CL) biosensor for oxalate combined with flow injection analysis is proposed in this paper. The analytical reagents involved in the CL reaction, including luminol and cobalt(II), were both immobilized on an ion exchange resin column, while the biological material spinach tissue was packed in a mini-glass column. By the oxalate oxidase-catalyzed reaction in the plant tissue column, hydrogen peroxide was produced, which could react with luminol and cobalt(II) being released from the ion exchange column by hydrolysis to generate a CL signal. The CL emission intensity was linear with oxalate concentration in the range 0.6-100 µM and the detection limit was 0.2 µM. The biosensor was stable for 300 determinations and a complete analysis, including sampling and washing, could be performed in 2 min with a relative standard deviation of less than 5%.

"Investigation Of Problems Associated With The Determination Of Iodine In Glacial Acetic Acid Samples Using Flow Injection Analysis-inductively Coupled Plasma-mass Spectrometry"
Anal. Commun. 1999 Volume 36, Issue 8 Pages 295-298
Kathryn L. Ackley, Jason A. Day, Karen L. Sutton and Joseph A. Caruso

Abstract: Determination of iodine in glacial acetic acid is a major concern of acetic acid manufacturers and consumers. The use of ICP-MS for iodine determinations in acetic acid is hindered by memory effects that produce an elevated background signal necessitating long rinse times between samples. In this work, different analysis methods are employed in an attempt to minimize memory and matrix effects allowing for the accurate determination of iodine in glacial acetic acid using ICP-MS. Ammonium hydroxide solutions (3.7 and 7.4 M) were better at reducing the elevated iodine signal present after the introduction of an acetic acid sample than water or 0.3 M nitric acid. Memory effects were decreased when the sample was introduced by flow injection rather than constant sample aspiration. Peak areas generated by flow injection decreased significantly with increasing ammonium hydroxide concentration in the carrier solution. Iodine determinations made with 1.7 M ammonium hydroxide as the carrier solution were higher than determinations made with 3.7 M ammonium hydroxide as the carrier solution for the same samples, however, the percentage difference between the two determinations varied widely from sample to sample. All samples were analyzed by the method of standard additions in an attempt to compensate for matrix effects. This work illustrates the importance of the carrier solution in the determination of iodine in glacial acetic acid samples.
Iodine Organic compound Optimization Carry over

"A New Sandwich-type Assay Of Estrogen Using Piezoelectric Biosensor Immobilized With Estrogen Response Element"
Anal. Commun. 1999 Volume 36, Issue 7 Pages 281-283
Mo Zhihong, Long Xiaohui and Fu Weiling

Abstract: A new methodology, sandwich-type monitoring assay system using an estrogen response element (ERE)-immobilized piezoelectric biosensor in combination with flow injection technique, has been developed for analysis of estrogen (E). The principle of the assay is that the estrogen receptor (ER) captures estrogen and then the complex is bound with ERE immobilized on the sensor. It was confirmed that initial binding of the ERE with ER is significantly accelerated by the formation of an E-ER complex. This kinetic difference was monitored by real-time measurement of the resonance frequency of the ERE piezoelectric biosensor and applied to detect 17 β-estradiol. The calibration graph was linear in the range 10^-100 nmol L-1 with a detection limit of 7.8 nmol L-1, an RSD of 5.9% for 50 nmol L-1 (6 replicates), and one run time of 4 min. Gradient flow injection online connection to an array of ERE piezoelectric biosensors is in progress for the simultaneous determination of endogenous and synthetic estrogens in drinking water and urine. In comparison with present chromatographic methods coupled with MS, the proposed technique is simple, flexible and cheap and has great potential in applications such as field and on-site monitoring and screen testing of endocrine disruptors.

"Electrochemical Control Of Solid Phase Micro-extraction Using Unique Conducting Polymer Coated Fibers"
Anal. Commun. 1999 Volume 36, Issue 5 Pages 203-205
Thompson P. Gbatu, Ozcan Ceylan, Karen L. Sutton, Judith F. Rubinson, Ahmed Galal, Joseph A. Caruso and Harry B. Mark Jr

Abstract: The use of a solid phase micro-extraction (SPME) method with poly(3-methylthiophene) coated platinum micro-fiber electrodes to extract arsenate ions from aqueous solutions without derivatization is described. The fibers were fabricated by cycling the working electrode between -0.20 and +1.7 V (vs. Ag/AgCl) in an acetonitrile solution containing 50 mM 3-methylthiophene monomer and 75 mM tetrabutylammonium tetrafluoroborate (TBATFB) electrolyte. All electrochemical procedures (extraction and expulsion) were conducted in a three-electrode system. After fabrication, the conducting polymer film was immersed in the sample solution and converted to its oxidized, positively charged form by applying a constant potential of +1.2 V with respect to Ag/AgCl reference electrode. Arsenate ions migrated into the film to maintain electroneutrality. Upon subsequent reversal of the potential to -0.60 V vs. Ag/AgCl, the polymer film was converted to its reduced, neutral form and the arsenate ions were expelled into a smaller volume (200 µL) Of de-ionized water for analysis using flow injection with inductively coupled plasma mass spectrometric (ICP-MS) detection.
Derivatization Optimization

"Sol-gel Horseradish Peroxidase Biosensor For The Chemiluminescent Flow Determination Of Hydrogen Peroxide"
Anal. Commun. 1999 Volume 36, Issue 5 Pages 195-197
Jun Li, Ke-Min Wang, Xiao-hai Yang and Dan Xiao

Abstract: A chemiluminescent (CL) H2O2 sensor based on horseradish peroxidase (HRP) immobilized by the sol-gel method has been proposed in this paper. A new process of fabricating a non-cracking HRP encapsulated sol-gel membrane has been suggested. Flow injection analysis (FIA) was used to give reproducible results. Under optimum conditions, the sensor showed a linear response toward hydrogen peroxide in the range 0.01-2 mM with a detection limit of 8 µM. The linear relative coefficient r = 0.998. The sensor showed rapid response, good reproducibility (relative standard deviation = 2.4%) and a long lifetime of at least two months. The proposed sensor was used to determine a 30% H2O2 solution that has been stored for a long time. The results were in good agreement with the standard volumetric method.

"Laboratory Adaptation Of The Methylene Blue Method To Flow Injection Analysis: Towards In Situ Sulfide Analysis In Hydrothermal Seawater"
Anal. Commun. 1999 Volume 36, Issue 4 Pages 157-160
Pierre-Marie Sarradin, Nadine Le Bris, Dominique Birot and Jean-Claude Caprais

Abstract: This preliminary study presents the laboratory adaptation of the methylene blue method for the analysis of sulfide in hydrothermal seawater to flow injection analysis (FIA) before its integration on an in situ analyzer.. The manifold used after optimization enables us to work on a 0-450 µmol l-1 sulfide range with a detection limit between 0.1 and 0.4 µmol l-1 and a relative standard deviation < 1%. The following steps will be the adaptation of the manifold on the in situ analyzer. and field tests.

"Determination Of α,4-dihydroxy-3-methoxybenzeneacetic Acid (vanilmandelic Acid) By Flow Injection Analysis Coupled With Luminol-hexacyanoferrate(III) Chemiluminescence Detection"
Anal. Commun. 1999 Volume 36, Issue 4 Pages 131-134
Neil W. Barnett, Paul S. Francis, Simon W. Lewis and Kieran F. Lim

Abstract: A simple and robust method for the determination of the clinically significant molecule vanilmandelic acid (α,4-dihydroxy-3-methoxybenzeneacetic acid, 4-hydroxy-3-methoxymandelic acid) using now injection analysis with chemiluminescence detection is described. This compound was found to enhance the chemiluminescence from the reaction of luminol with hexacyanoferrate(III) in a basic medium. The calibration function obtained over the range from 2.5 x 10^-8 to 1.0 x 10^-6 mol L-1 approximated to linearity (r2 = 0.9995) with the equation of best fit of y = 1.72 x 10^8 x + 36.9, where y is the integrated signal (V s) and x is the concentration (mol L-1). Precision (as measured by relative standard deviation) was 2.6% for 5 replicate analyzes of a standard (2.5 x 10^-7 mol L-1) and the limit of detection (3s) was 2 x 10^-8 mol L-1, Preliminary investigations revealed that the structurally similar homovanillic acid inhibits the emission of chemiluminescence from the luminol-hexacyanoferrate(III) reaction and that the kinetics of light emission were different from those of the vanilmandelic acid enhanced reaction.

"FTIR Spectroscopy As Detection Principle In Aqueous Flow Analysis"
Anal. Commun. 1999 Volume 36, Issue 4 Pages 123-126
R. Schindler and B. Lendl

Abstract: Whereas FTIR spectroscopic detection is routinely used in gas chromatography (B. Erikson, Anal. Chem., 1998, 70, 801A), its use for liquid chromatography (LC) and flow injection analysis (FIA) is a rather exotic exception. The most prominent reason is the strong IR absorption of most of the common solvents, especially water. Hence FTIR spectroscopy is normally not even considered a valuable detection method. This practice neglects that FTIR spectroscopy offers some unique features which now, using modern instrumentation, can be exploited in an advantageous manner. It is the aim of this Highlight article to demonstrate the wide range of possible applications in LC and FIA. To regard FTIR spectroscopy as too exotic for routine use may be a luxury paid for with the neglect of a simple analytical approach. The term flow analysis (FA) will be used to provide a common cover for both LC and FIA because both rely on the injection of a sample into a flowing stream, passage through a modulator and recording of transient peaks. Although the processes taking place in the modulator are different, being chemical reactions in FIA and separations in LC, the same interfaces can be used for a FTIR spectrometer as a detector. The interfaces used can be divided into two categories, flow through cells where the liquid is probed directly, and solvent removal interfaces where the analyte is separated from the carrier liquid prior to detection. It is necessary to emphasize the complementary nature of these techniques (D. E. Pivonka and K. M. Kirkland, Appl. Spectrosc., 1997, 51, 866) and this Highlight will stress their particular strengths and weaknesses. Special focus is laid on aqueous phase systems because of their high importance in biological systems. As water is certainly the most challenging solvent for IR detection, equal or even better performance of the presented approaches can be expected for other solvents. Additionally three developments will be discussed in detail with respect to their prospects for FA-FTIR instruments: the increasing availability of sophisticated chemometric methods, the miniaturization of analytical instruments and application to combinatorial chemistry.
Combinatorial chemistry

"A Tungsten Oxide Coated Wire Electrode Used As A PH Sensor In Flow Injection Potentiometry"
Anal. Commun. 1998 Volume 35, Issue 12 Pages 395-398
Lucy T. Dimitrakopoulos, Telis Dimitrakopoulos, Peter W. Alexander, Dusan Logic and D. Brynn Hibbert

Abstract: A W oxide wire electrode is described for use as a pH electrode in a portable battery-powered flow injection analyzer described previously. The W oxide electrode exhibits a linear response of 44.8 ± 0.5 mV change per pH unit over a wide range, pH 2-11 in the steady-state mode. In the flow injection mode, the W oxide wire electrode exhibited a slope of 42.4 ± 0.9 mV per pH unit. The W oxide electrode was employed to determine the pH of various alcohol beverages and environmental water samples.
pH Beverage Environmental Potentiometry Electrode Apparatus Detector Remote instrument

"FIA Determination Of Chromium(III) In Tap Water With Chemiluminescence Detection"
Anal. Commun. 1998 Volume 35, Issue 12 Pages 389-390
A. Economou, A. K. Clark and P. R. Fielden

Abstract: Cr(III) has been determined by measuring the light emitted as a result of the Cr(III)-catalyzed reaction between luminol and hydrogen peroxide. Increase in the sensitivity of the determination was achieved by introducing bromide into the reaction mixture while the selectivity was improved by the addition of EDTA. All the operations were performed online in an automated FIA system. The calibration curve for Cr(III) was linear in the range 0-500 µg L-1 and the limit of detection was 0.5 µg l-1. The method was applied to the determination of Cr(III) in tap water; the Cr(III) concentration. varied between 10 and 20 µg L-1 with a typical coefficient of variation of 2% (n = 5).
Chromium(III) Water Chemiluminescence Indirect EDTA

"Optimization Of Microwave Digestion For Determination Of Selenium In Human Urine By Flow Injection-hydride Generation-atomic Absorption Spectrometry"
Anal. Commun. 1998 Volume 35, Issue 11 Pages 361-364
Fangshi Li, Walter Goessler and Kurt J. Irgolic

Abstract: A microwave digestion program, which completely decomposes and oxidizes selenium compounds in urine to selenate, was developed by monitoring the pressure and the temperature during microwave digestion. The efficient decomposition and quant. recovery of trimethylselenonium iodide spiked into urine was achieved in 18 min using the optimized microwave program reaching 200°C and 8 bar. The selenate in the digest was reduced to selenite by hydrochloric acid with the aid of microwave energy. Urea was found useful to eliminate NOx fumes, which might be absorbed in the digest and interfere in the determination of selenium by flow injection-hydride generation-at. absorption spectrometry (FI-HG-AAS). The recovery of trimethylselenonium iodide, selenomethionine, selenoethionine added to urine was 96.5-105%. The whole procedure, FI-HG-AAS determination following microwave digestion of urine sample and microwave reduction of selenate in the digests into selenite, was checked with two Standard Reference Materials 2670 (toxic metals in human urine). The results showed good agreement with the certified values (normal level 30 ± 8 µg Se L-1 and elevated level 460 ± 30 µg Se L-1). The detection limit of the whole procedure was 3 µg Se L-1 urine. Selenomethionine and selenoethionine were found unstable during the microwave heating used to reduce selenate to selenite. Such a microwave reduction procedure should be cautiously used to distinguish selenate from selenite in the matrixes which might contain organic selenium compounds
Selenium Trimethylselenium Selenomethionine Selenoethionine Urine NIST 2670 Spectrophotometry Sample preparation Interferences Reference material Optimization

"Automated Solid Phase Extraction Of Theophylline By Sequential Injection On Renewable Column"
Anal. Commun. 1998 Volume 35, Issue 11 Pages 357-359
Brian Dockendorff, David A. Holman, Gary D. Christian and Jaromir Ruzicka

Abstract: A miniaturized and fully automated solid phase extraction system was developed based on sequential injection onto a renewable microcolumn of an ion exchanger. Extraction of theophylline from caffeine solutions was used as an example of sample preparation An important feature, compared to commercial sorbent extraction systems, was the elimination of prepackaged sorbent cartridges by using an automatically renewable microcolumn. The method has evolved from recent innovations in sequential injection analysis using a jet ring cell that entraps ion exchanger beads and discards them after completion of the monitoring cycle.
Theophylline Ion exchange Stopped-flow Renewable surface Sequential injection Jet ring cell Solid phase extraction

"Determination Of Zirconium With Xylenol Orange By Flow Injection Spectrophotometry: Application To Eluates From Technetium-99m Generators"
Anal. Commun. 1998 Volume 35, Issue 3 Pages 107-108
Kate Grudpan, Mayuree Utamong and Colin G. Taylor

Abstract: A procedure for the determination of Zr using Xylenol Orange was developed from a conventional spectrophotometric one. An acidic medium of sulfuric acid rather than HClO4 was adopted, to achieve a fast reaction rate and greater sensitivity. Under optimized conditions, calibrations are linear over a range of at least up to 10 ppm of Zr. The detection limit is 0.08 ppm and precisions (RSDs) at the 1, 3 and 5 ppm levels were 2.3, 1.9 and 0.2, respectively. The procedure is free of interferences from species which are present in the eluate from a 99 mTc generator, and was applied to the determination of Zr in such an eluate.
Zirconium Waste Spectrophotometry Optimization

"Pulsed Flow Chemistry. A New Approach To The Generation Of Concentration Profiles In Flow Analysis"
Anal. Commun. 1998 Volume 35, Issue 3 Pages 97-101
Xue D. Wang, Terence J. Cardwell, Robert W. Cattrall and Graeme E. Jenkins

Abstract: Pulsed flow chemical (PFC) is described as a new approach to automated online anal. chemical In contrast to existing flow-based anal. chemical methods, PFC is characterized by pulsed flow, turbulent mixing and low axial dispersion. The PFC system is fully computerized and all operations are under software control. Consequently, most flow analysis methods (e.g., flow injection, continuous-flow, flow titration, etc.) can be selected with a simple click of the mouse. The system is easily miniaturized and portable which makes it particularly suited to field instrumentation. The system has been tested using several flow-based techniques including online titration for the determination of calcium in waters with potentiometric detection and a calcium ion sensor.
Calcium Environmental Potentiometry Gradient technique Axial dispersion Turbulent flow Pulsed flow Titrations

"Investigations Into The Simultaneous Determination Of Bismuth And Selenium By 'in Atomizer Trapping' Electrothermal Atomic Absorption Spectrometry"
Anal. Commun. 1997 Volume 34, Issue 11 Pages 359-362
James Murphy, Phil Jones, Gerhard Schlemmer, Ian L. Shuttler and Steve J. Hill

Abstract: Initial investigations are described for the simultaneous determination of Bi and Se by hydride generation 'in atomizer trapping' electrothermal atomic absorption spectrometry. A fully automated micro-scale flow injection hydride generation system with 'in atomizer trapping' electrothermal atomic absorption spectrometry was employed. Using the recommended single element hydride generation conditions and optimized multi-element ETAAS parameters, simultaneous signals for Bi and Se were obtained. Calibration graphs were constructed in the range 0-5 g L-1 and method detection limits of 0.13 and 0.19 g L-1 for Bi and Se, respectively, established. Better than 2% precision was obtained for 3.0 g L-1 (n = 5) for Bi and Se. Carry-over effects were seen for Se and were reduced by the use of an internal atomizer gas flow during the 'in atomizer trapping' step.
Bismuth Selenium Spectrophotometry Simultaneous analysis

"Flow Injection Proton Nuclear-magnetic-resonance Spectroscopy Combined With Pattern-recognition Methods Implications For Rapid Structural Studies And High-throughput Biochemical Screening"
Anal. Commun. 1997 Volume 34, Issue 11 Pages 339-341
Manfred Spraul, Martin Hofmann, Michael Ackermann, Andrew W. Nicholls, Stephen J. P. Damment, John N. Haselden, John P. Shockcor, Jeremy K. Nicholson and John C. Lindon

Abstract: The applicability of novel NMR flow probe technology has been tested by the measurement of 300 MHz H-1 NMR spectra of a series of rat urine samples, Compared with conventional automatic operation, the method resulted in a significantly increased rate of sample throughput, required minimal spectrometer optimization before each measurement and avoided the need for expensive and fragile NMR sample tubes, The NMR approach has been coupled with computer methods for spectral data reduction and classification using, in this case, principal components analysis, The flow probe NMR approach offers distinct advantages in situations where large numbers of samples require NMR analysis in a short period of time, These could include routine samples from high throughput chemical synthesis, biofluid samples for drug toxicity monitoring as shown here, samples for clinical diagnosis or real-time analysis in chemical production facilities. 7 References
Drugs Urine Nuclear magnetic resonance Principal component analysis Optimization

"Thermometric Sensing Of Fluoride By Adsorption On Ceramic Hyroxyapatite Using Flow Injection Analysis"
Anal. Commun. 1997 Volume 34, Issue 11 Pages 329-332
Salah Salman, Karsten Haupt, Kumaran Ramanathan and Bengt Danielsson

Abstract: A thermometric method for detection of fluoride has been developed that relies on the specific interaction of fluoride with hydroxyapatite. The detection principle is the measurement of the enthalpy change upon adsorption of fluoride onto the ceramic hydroxyapatite by temperature monitoring using a thermistor-based flow injection calorimeter. The detection limit for fluoride was 5 M (0.1 ppm) which is in the same range as that of a commercial ion-selective electrode. The method could be applied to fluoride in aqueous solution as well as in cosmetic preparations. The system yielded highly reproducible results over at least 6 months without the need for replacing or regenerating the ceramic hydroxyapatite column. The ease of operation of thermal sensing and the ability to couple the system to flow injection analysis provides a versatile, low-cost and fast detection method for fluoride.
Fluoride Thermometry Solid phase detection

"Measurement Of Sulfite Using Sulfite Oxidase And Luminol Chemiluminescence"
Anal. Commun. 1997 Volume 34, Issue 10 Pages 299-301
Satoshi Sasaki, Yoshiko Arikawa, Mifumi Shimomura, Kazunori Ikebukuro and Isao Karube

Abstract: Measurement of sulfite using sulfite oxidase and luminol chemiluminescence was performed. Sulfite oxidase from chicken liver was immobilized in a reactor column filled with polysaccharide gel beads. The effects of buffer solution, hydrogen peroxide concentration and sulfite concentration on the chemiluminescence intensity were examined. For the same concentration of hydrogen peroxide, carbonate buffer solution system showed about 3 times higher chemiluminescence intensity than is the case with berate buffer solution, Hydrogen peroxide produced through the enzymatic reaction reacted with luminol to produce chemiluminescence. The intensity of the light emitted was proportional to the sulfite concentration at 3 x 10^-9-10^-6 M of sulfite. With the use of peroxidase from Arthromyces ramosus, the lower limit of sulfite detection was 3 x 10^-10 M, which is the lowest concentration detectable using a biosensor. Relative standard deviation (RSD) of the response for this sulfite concentration was within 5% (n = 5). 9 References
Sulfite Chemiluminescence Sensor Immobilized enzyme Buffer

"Sequential Injection Acid-base Titration - A Useful Application For Process Analytical Science"
Anal. Commun. 1997 Volume 34, Issue 5 Pages 147-151
Jacobus F. van Staden and Hanneli du Plessis

Abstract: The method is based on sequential injection of base titrant, acid analyte and base titrant into a carrier stream of water, giving a stack of well-defined zones in the holding coil (4.8 m x 1.02 mm i.d.) prior to reversed flow-through a reaction coil to the detector. A diagram of the system is given. Bromothymol blue (0.0016%) was included in the base (NaOH) as indicator for detection at 620 nm. The optimal flow rate was 2.13 ml/min. The calibration graph was linear for 0.01-0.1 M HCl using 1 mM NaOH as titrant. The RSD were Only 700 µL base and 100 µL acid sample was required per analysis. A sequential injection (SI) titration system is proposed for the titration of a strong acid with a strong base. The concept is based on the sequential injection of a base titrant, acid analyte and a base titrant zone into a distilled water carrier stream, giving a stack of well-defined zones adjacent to each other in a holding coil, which is swept by reversal through a reaction coil to the detector. The base zones contain Bromothymol Blue as indicator and the endpoint was monitored spectrophotometrically at 620 nm. A linear relation between peak width and logarithm of acid concentration. was obtained in the range 0.01 to 0.1 mol L-1 of HCl with 1 x 10^-3 mol L-1 of NaOH as titrant. Other linear ranges are possible by changing the titrant concentrations. The results obtained of the sequential injection titration of samples is in good agreement with a standard potentiometric method with an relative standard deviation < 0.30%. The system is fully computerized with a sample frequency of 30 samples h-1.
Acids Bases Spectrophotometry Method comparison Sequential injection Titrations Process control

"Flow Injection Potentiometric Detection Of Phosphates Using A Metallic Cobalt Wire Ion-selective Electrode"
Anal. Commun. 1997 Volume 34, Issue 3 Pages 93-95
Zuliang Chen, Roland De Marco and Peter W. Alexander

Abstract: Sample (100 µL) was injected into a carrier stream (1 mL/min) of 0.04 M potassium acid phthalate of pH 5 and carried to a detector comprising a metallic Co wire ISE (0.5 mm diameter x 4 cm long) and a Ag/Ag Cl reference electrode. The calibration graph was linear for 10 µM to 5 mM phosphate and the detection limit was 1 µM. The RSD for 0.5 mM phosphate was 3% (n = 8). Flow injection potentiometric detection of phosphate has been undertaken using a metallic cobalt wire ion-selective electrode, The electrode response to phosphate was characterized by potential readings of high stability versus a Ag/AgCl reference electrode, and results have shown that the electrode displays high sensitivity and selectivity towards the phosphate ion, The metallic cobalt wire electrode was used for the flow injection potentiometric detection of phosphate using a 0.04 mol L-1 potassium hydrogen phthalate carrier at pH 5.0. A linear response with a slope of -38.00±0.5 mV decade-1 change in phosphate activity was obtained in the range 1.0 x 10^-5 - 5.0 x 10^-3 mol L-1, and the detection limit was 1 x 10^-6 mol L-1, The phosphate electrode described in this paper is robust, simple to use, highly selective, inexpensive and highly stable.
Phosphate Polyphosphates Potentiometry Electrode Electrode Detector Interferences

"Determination Of Carbohydrates By Flow Injection With Direct Chemiluminescence Detection"
Anal. Commun. 1996 Volume 33, Issue 10 Pages 367-369
Irena B. Agater, Roger A. Jewsbury and Kath Williams

Abstract: A solution of sugar sample was mixed with 0.2 M Mn(II) in 2 M H2SO4 in a flow injection system (details given) at a flow rate of 1.9 mL/min for each stream. Then 60 µL 25 mM KMnO4 (permanganate oxidant) was injected into the flowing stream. Two detectors were used; a photomultiplier tube with a S20 photocathode at 1200 V and a commercial chemiluminescence photodiode detector. Calibration graphs were linear from 10^-4 to 10^-1 M for five monosaccharides, lactose and sucrose, sugar alcohol mannitol, glycerol and ascorbic acid (for comparison). RSD was 16% (n not given).
Carbohydrates Chemiluminescence Photodiode

"Simple Convenient Method For Measuring Injection Volumes In Flow Injection And Sequential Injection Analysis"
Anal. Commun. 1996 Volume 33, Issue 9 Pages 339-341
Jacobus F. van Staden and Daniel Malan

Abstract: A sample loop was loaded with an aqueous dye standard solution (methyl orange) then flushed quantitatively into a cuvette using pure water. The mass of liquid in the cuvette was measured and the dilution of the standard was measured by spectrophotometry. The dilution of the methyl orange was compared with a standard calibration curve. This method was more accurate than methods where the inner dimensions of the injection device were not precisely know. This method is within the 95% confidence level; RSD was 0.8% (n = 6). Calibration graphs were linear from 20-70 µL injection volumes.
Sequential injection

"Online Kinetic Measurement Of Water Toxicity Using The Photobacterium Vibrio Fischeri"
Anal. Commun. 1996 Volume 33, Issue 9 Pages 335-338
Peter R. Fielden, Tom McCreedy, Richard D. Snook and Bernard J. Treves Brown

Abstract: A new approach to toxicity measurements is described; the quenching of luminescent bacterium Vibrio fischeri is used with an online PC-controlled flow analysis system (schematic given). Two toxic compounds were determined: 3,5-dichlorophenol and formaldehyde. Bacteria samples were reconstituted using microtox medium (Microbics) and challenged with different concentrations of each of the toxic substances in the ppm range. The PC-controlled FIA system cycled through four stages: flush (samples are mixed with saline); mixing (photobacterial reagent was added); read (photomultiplier detection); then the system was flushed with saline and the rate of light decay was calculated using a PC (theory given). The entire system was maintained at 15°C. Calibration graphs of light decay vs. time gave an indication of relative toxicity.
Water Kinetic Quenching

"Electrogenerated Chemiluminescence Determination Of Some Local-anesthetics"
Anal. Commun. 1996 Volume 33, Issue 5 Pages 171-174
Andrew W. Knight and Gillian M. Greenway

Abstract: This work describes the use of the emerging technique of electrogenerated chemiluminescence (ECL) for the determination of some local anaesthetics using an ECL reaction with tris(2,2'-bipyridine)ruthenium(II). Five local anaesthetic compounds are studied, and experimental conditions optimized to achieve detection limits of 5 x 10^-8 mol I-1 for bupivacaine and procaine, and 7 x 10^-8 mol I-1 for lignocaine. The ECL method was successfully applied to the determination of lignocaine in a commercial product.
Anaesthetics Lignocaine Pharmaceutical Chemiluminescence HPLC Optimization

"Determination Of Amitriptyline Using Electrogenerated Chemiluminescence"
Anal. Commun. 1996 Volume 33, Issue 4 Pages 139-141
Sarah J. L. Dolman and Gillian M. Greenway

Abstract: Amitriptyline (0.05M) was mixed with 1 mM tris(2,2'-bipyridyl)ruthenium(II) and 0.05 M phosphate buffer of pH 7. A portion (100 µL) was injected directly in to the flow cell of an FIA system described previously (Knight et al., Anal. Proc., 1995, 32, 125). A potential was applied using a three-electrode potentiostat; a Pt disc and a Ag electrode were the working and pseudo-reference electrodes, respectively. A Pt wire was incorporated downstream of the flow cell as a counter electrode. Detection was with a photomultiplier tube held at 850 V. Optimum operating conditions were a flow rate of 2 ml/min and a 2.5 s voltage pulse of 1.26 V. Calibration graphs were linear over three orders of magnitude; the detection limit was 0.3 µM-amitriptyline (94 ppb). This technique is suitable for detection of the drug at both therapeutic and toxic concentrations.
Amitriptyline Pharmaceutical Chemiluminescence

"Flow Injection With Diaphragm Pump And Amperometric Detector"
Anal. Commun. 1996 Volume 33, Issue 2 Pages 75-77
Teiji Kakizaki, Kazunori Imai and Kiyoshi Hasebe

Abstract: A FIA system is described which has a diaphragm micropump with a moving section (actuator) and a pump section diaphragm). The actuator consists of two layers of piezoelectric elements of ceramic cemented together with three foil electrodes on the outer and inner surfaces. This vibrator is moulded in to rubber (diagram and details given). The driving source for the actuator was 0-100 V a.c., 50 Hz. Amperometric measurements were made with a Pt-disc, Ag/AgCl and Pt coil was working, reference and counter electrodes, respectively. This system enabled reliable amperometric measurements to be made in a FIA system with a carrier delivery system that gave a fluent constant flow of solutions without the use of pulse pumping devices. The method could be applied to the monitoring of ascorbic acid in soft drinks.
Ascorbic acid Soft drink Amperometry Electrode Apparatus Pump

"Flow Injection Chemiluminescence Determination Of Imipramine And Chlorpromazine"
Anal. Commun. 1996 Volume 33, Issue 1 Pages 31-33
J. L. Lopez Paz and Alan Townshend

Abstract: Analysis was carried out in a flow system (diagram given) consisting of a peristaltic pump, injection valve, mixing piece, flow coil and photomultiplier tube. Drug solutions were injected in to a 2 M H2SO4 stream which mixed with a 4 M KMnO4/2 M H2SO4 stream; flow rates were 1.74 ml/min. The peak height of the emission response was measured. This technique was simple and rapid, 85 and 100 samples/h for imipramine and chlorpromazine, respectively. RSD were 1% and 1.2% (n = 8) for 10 µM-imipramine and 25 µM-chlorpromazine, respectively; corresponding detection limits were 50 µM and 20 µM. The method was applied to the analysis of urine. Recoveries were 103.5% and 99.2% for imipramine and chlorpromazine, respectively; RSD was 4%.
Imipramine Chlorpromazine Urine Chemiluminescence