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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Titrations

Classification: Application -> Titrations

Citations 167

"Non-spectrophotometric Methods For The Determination Of Vitamin C"
Anal. Chim. Acta 2000 Volume 417, Issue 1 Pages 1-14
S. P. Arya, M. Mahajan and P. Jain

Abstract: In view of the widespread use of Vitamin C, a large number of methods have been developed for quantifying Vitamin C contents in natural and fortified food samples and pharmaceuticals. It is therefore essential to assess these methods. Accordingly, this paper reviews non-spectrophotometric methods. 277 references.
Ascorbic acid Pharmaceutical Fruit Soft drink Fluorescence LC Polarography

"Determination Of Indigo In Dyebaths By Flow Injection Analysis And Redox Titrations"
AATCC Rev. 2001 Volume 1, Issue 4 Pages 41-45
Judson T. Merritt III, Keith R. Beck, C. Brent Smith, Peter J. Hauser, and Warren J. Jasper

Abstract: Flow injection analysis (FIA) has been developed as a real-time analytical technique for determining individual water-soluble and disperse dye concentrations in batch dyebaths. In this paper, a comparison of FIA and standard titrimetric redox methods for monitoring indigo in continuous dyebaths is reported. Several indigo solvent systems were investigated to determine which was best for FIA determinations. Indigo concentration data from simulated continuous dyebaths were generated by FIA and titration. Titration also generated the bath concentration of sodium hydrosulfite. FIA determination of indigo concentrations was more rapid, precise, and accurate than titrametric methods. The FIA method applies to pure indigo dyeing and needs refinement to determine indigo concentration in the presence of sulfur dye desorbed from yarn.
Indigo Dyes, disperse Dye bath Spectrophotometry

"A Robust Multisyringe System For Process Flow Analysis Part II. A Multi-commuted Injection System Applied To The Photometric Determination Of Free Acidity And Iron(III) In Metallurgical Solutions"
Analyst 2000 Volume 125, Issue 12 Pages 2364-2371
Fernando Albertús, Andreu Cladera and Victor Cerda

Abstract: A new software-controlled volume-based system for sample introduction in process flow injection analysis was developed. By using a multi-syringe burette coupled with one or two additional commutation valves, the multi-commuted injection of precise sample volumes was accomplished. Characteristics and performance of the injection system were studied by injecting an indicator in a buffered carrier. Three configurations were implemented in order to achieve two different tasks: the single injection of a sample in a two- or three-channels manifold, and the dual injection into different streams. The two channel flow system using the single injection was applied to the determination of free acidity in diluted samples containing high levels of iron(iii), by employing the single point titration methodology. The precipitation of ferric hydroxide was prevented using the ammonium and sodium salts of oxalate and acetate as buffer titrant. Methyl Red was employed as indicator. The procedure allows determination of acid concentration in solutions with a Fe(iii)/H+ molar ratio up to 0.2. Samples with higher Fe(iii)/H+ molar ratios were spiked with a known strong acid at dilution. The three-channel configuration was applied to the determination of ferric ions, using, as reagent, a merging mixture of sulfuric acid and potassium thiocyanate. The double injection system was implemented in series in a single (three-channel) manifold in such a way that a different injection volume and a changed reagent were used for each analyte. It was applied to the separated or sequential determination of free acidity and ferric ions. In this configuration, iron(iii) was determined using 0.5-0.7% (w/v) sodium salicylate solution as reagent. The systems can operate at up to 100, 84 and 78 injections per hour, respectively. Determinations on synthetic and process samples compared well with the reference values and procedures. Recoveries of 95-102% with a maximum RSD value of 5.4% were found for acidity. The respective values obtained for iron determinations were 96-105% and 4.3%.
Acidity Iron(III) Industrial Spectrophotometry

"Non-linear Calibration In Single Point Flow Titration Of Protolytes - A Comparison Of Model Options By Using Delta Test"
Anal. Chim. Acta 2000 Volume 414, Issue 1-2 Pages 221-237
Fernando Albertús, Isel Cortés, Manuel Alvarez and Victor Cerda

Abstract: The complete description of the non-linear absorbance/concentration relationship obtained for systems used in single point photometric flow injection titrations of acids and bases is presented. The applicability of different models for fitting calibration data, as well as the more frequently used data processing options, are investigated under normal and restraining conditions by using experimental and simulated data sets. Theoretical and empirical models are examined in order to choose the simplest and the more efficient ones to provide good recoveries. The comparison among models is based on a novel statistical criterion (Delta Test) for contrasting the prediction efficiency by detecting systematic errors in estimated concentrations.
Acids Bases Spectrophotometry

"Study On The Implementation Of Flow Titrations In Sequential Injection Analysis"
Lab. Rob. Autom. 1999 Volume 11, Issue 4 Pages 207-216
J. M. Estela, F. Mas, A. Cladera, V. Cerdà

Abstract: Several variables that affect flow spectrophotometric titrations in sequential injection analysis (SIA) systems were studied by using titration of a strong acid with a strong base as a model; blue bromothymol was used as an indicator and distilled water was used as a carrier. Both possibilities of performing titrations on SIA systems according to the aspiration sequences (a) titrant B/sample/titrant A and (b) titrant/sample are considered. In case (a) the possibilities regarding the use of different volumes and/or different concentrations of titrant reagents were studied and are discussed. The established methodology allows hydrochloric acid determinations with 0.1 M sodium hydroxide within the range 32-1000 mM by means of logarithmic calibration curves. The analysis rate is of 5 min/sample.
Acids, strong Hydrochloric acid Spectrophotometry

"Analytical Options For Control Of Acids And Bases In Hydrometallurgical Processes"
Process Control Qual. 1999 Volume 11, Issue 4 Pages 289-300
Fernando Albertús, Isel Cortés, L.-G. Danielsson and Folke Ingman

Abstract: The most common procedures for the determination of acids and bases in hydrometallurgical process liquors are reviewed and compared. Automated batch titrations, performed by stepwise addition of titrant and using Gran plots for evaluation are reliable but slow compared to flow techniques. Continuous flow titrations are grouped into three classes: Flow Injection Titration, Single Point Flow Injection Titration, and Triangle-programmed Flow Titrations. Furthermore, Sequential Injection Analysis is also considered for process applications. Each one of these methods has advantages and drawbacks. An overview of the most common application problems, and the way they are solved with each methodology, is given. The analytical characteristics of the described procedures are given as well as a guide for the choice of technique for a given application.
Industrial

"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 Hernández-Cassou, Romà 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%.

"A Compact Titration Configuration For Process Analytical Applications"
Anal. Chim. Acta 1999 Volume 378, Issue 1-3 Pages 211-217
Robert Hoogendijk

Abstract: A configuration for wet-chemical process analysis is proposed consisting of one piston burette, a selector valve and a reaction cell. The feasibility of the configuration is shown by optimising a simple acid/base titration setup. Other applications of this configuration for complexometric-, precipitation-, and back-titration, standard addition and photometric methods are discussed. The configuration offers great flexibility towards these methods without the need for modification, while its robustness makes it especially suitable for online process analysis.
Spectrophotometry

"An Automatic Titrator Based On A Multicommutated Unsegmented Flow System - Its Application To Acid-base Titrations"
Anal. Chim. Acta 2000 Volume 407, Issue 1-2 Pages 213-223
Cristina M. N. V. Almeida, Rui A. S. Lapa, José L. F. C. Lima, Elias A. G. Zagatto and M. C. U. Araújo

Abstract: A continuous flow methodology to perform acid-base titrations is described. The titrations are carried out on a multicommutated flow system which simulates batch titration procedures. The titration strategy is based on sequential insertion of increasing titrant and decreasing titrand volumes in a reactor, thus accomplishing complete titration curves. The assessment of the titration end point is similar to that of conventional batch procedures. The theoretical model for the determination of titrand concentration without requiring any calibration process is presented and discussed. The present system was evaluated in vinegar acidity determinations and provided an accuracy better than 3% with a good repeatability (relative standard deviation (RSD) = 2.5%; n = 10) and reproducibility (RSD < 5%). The titration accuracy is time-dependent and has been tested in the 2-10 min range.
Acids Bases Food Potentiometry Electrode

"Determination Of Surfactant Concentration Using Micellar Enhanced Fluorescence And Flow Injection Titration"
Talanta 2000 Volume 50, Issue 6 Pages 1283-1289
Charles A. Lucy and Josephine S. W. Tsang

Abstract: Flow injection titration was used for the determination of anionic, cationic, nonionic and zwitterionic surfactants. The procedure was based on the micellar-enhanced fluorescence of 1,8-anilino-naphthalene sulfonate (ANS). Samples were injected into a carrier stream of phosphate buffer and 1.0 mol 1 (-) (1) NaCl. The sample then passed through a mixing chamber which generated the exponential peak shape needed for the titration as well as diluted the sample in the carrier stream to control the pH and ionic strength of the sample. The peak width was linearly related to the logarithm of the surfactant concentration. The minimum detectable concentration was governed by the critical micelle concentration for anionic, zwitterionic and nonionic surfactants, but below the critical micelle concentration for cationic surfactants. The linear range extended for similar to 1.5 orders of magnitude. Reproducibility ranged from 12% at the lower end of the calibration range to 1.1% at higher concentrations. For SDS recoveries of 82-108% were achieved in matrices as concentrated as 1 mol 1 (- 1) in NaCl or Na2SO4.
Surfactants, anionic Surfactants, cationic Surfactants, zwitterionic Fluorescence

"Spectrophotometric Determination Of PK(a) Values Based On A PH Gradient Flow Injection System"
Anal. Chim. Acta 2000 Volume 408, Issue 1-2 Pages 135-143
Javier Saurina, Santiago Hern&aacute;ndez-Cassou, Rom&agrave; Tauler and Anna Izquierdo-Ridorsa

Abstract: This paper describes a pH gradient flow injection method for fast spectrophotometric determination of acidity constants. The flow injection system consists of a three-channel manifold in which the sample bolus is injected between acidic and basic zones. Therefore, the front of the flow injection peak is made acidic while the tail of the peak is alkalinized, and consequently, a pH gradient from acidic to basic medium is generated along the flow injection peak in an easy and reproducible way. The whole procedure is composed of two steps; first, the in situ determination of the pH gradient profile by using a standard compound with a known pK(a) value, and second, this pH gradient profile is used to calculate the pK(a) of an unknown compound. An alternating least squares multivariate curve resolution method is used in both steps to resolve the concentration profiles of the acidic and basic species in the standard and in the unknown samples which are the basis of the calculations. The method is tested using several nucleic acid components. An additional advantage of the proposed method is that no pH experimental measurement is needed for the fast determination of pK(a) values. Results obtained using the proposed procedure are consistent with those listed in the literature.
Acidity, constants Nucleic acids Water Spectrophotometry

"Microelectrode Arrays With Interacting Diffusion Layers: Special Applications"
Chem. Listy 2001 Volume 95, Issue 1 Pages 18-21
P. Tomcik, D. Bustin and I. Novotny

Abstract: The review deals with special applications of interdigitated array (IDA) microelectrodes. A high collection efficiency in comparison with RRDE (rotatory ring disc electrode) can be used for the determination of species by titration in the diffusion layer of an IDA system. The titrant (iodine, bromine, and hypobromite) is galvanostatically generated on one IDA segment and another segment serves as an amperometric detector with constant potential, which corresponds to the opposite reaction to that of titrant electrochemical generation. The method is simple, sensitive to the species (ammonium, arsenic, thiosulfate. allyl alcohol, iodide) and can also be used in microanalysis.

"Evolution Of The Commutation Concept Associated With The Development Of Flow Analysis"
Anal. Chim. Acta 1999 Volume 400, Issue 1-3 Pages 249-256
Elias A. G. Zagatto, Boaventura F. Reis, Cl&aacute;udio C. Oliveira, Raquel P. Sartini and Marco Aur&eacute;lio Z. Arruda

Abstract: Evolution of the commutation concept has lead to the proposal and development of different generations of flow analyzers. Since the inception of the air-segmented flow systems till the availability of modern flow injection, sequential injection and other flow-based analytical systems, a noteworthy improvement of the commutating devices has been noted. Multi-functional manifold is described as a polyvalent approach for methodology implementation in a flow analyzer. It permits the investigation of mixing conditions under different flow patterns (unsegmented, segmented, monosegmented) with optional exploitation of the stopped-flow approach. For this purpose, spectrophotometric or turbidimetric measurements eventually affected by Schlieren noise were considered. Potentialities and limitations of the manifold are discussed in relation with methods based on relatively fast or slow chemical reactions. As applications, phosphate and chloride determinations in plant digests and natural waters were selected. The manifold is characterized by high versatility and may work in connection with different flow configurations. Development will certainly lead to simple, versatile and miniaturized analyzers, able to run samples in a personalized fashion. In addition, random reagent selection, full automation, expansion of the analytical application range and increasing potentialities of the already existing methodologies are devised.
Copper Plant Sample preparation Spectrophotometry Turbidimetry

"Flow Injection Analysis. 9. A New Approach To Continuous-flow Titrations"
Anal. Chim. Acta 1977 Volume 92, Issue 2 Pages 235-249
J. Rika, E. H. Hansen and H. Mosbaek

Abstract: Studies of dispersion patterns in nonsegmented streams flowing through narrow open tubes show that it is possible to obtain highly reproducible concentration. gradients within a sample zone injected into the moving stream. By varying the geometry of the flow path, low, medium, and high dispersion patterns can be achieved; the high dispersion pattern forms the basis for a new approach to continuous-flow titrimetry. In this type of titration, discrete samples are passed through a gradient device and are then mixed with a continuously flowing stream of titrant of fixed concentration. The new technique was tested for potentiometric as well as spectrophotometric end-point indication. A simple 1-channel system allows titrations to be performed automatically in <1 min.
Acetaminophen Calcium Potentiometry Spectrophotometry

"A Novel Titration Technique For The Analysis Of Streamed Samples - The Triangle-programmed Titration Technique. 3. Titrations With Electrically Generated Bromine"
Anal. Chim. Acta 1978 Volume 100, Issue 1 Pages 181-191
G. Nagy, Zs. Feh&eacute;r, K. T&oacute;th and E. Pungor

Abstract: The triangle-programmed titration technique brings together the advantages of flow-through techniques and titration methods. Titrations with bromine prepared by current-programmed electrolysis are reported; suitable instrumentation is described for biamperometric end-point indication. The electrode processes and the effects of different parameters of the reagent addition program are discussed. The applicability of the method to organic and inorganic substances is described. The technique is applicable to flowing sample solutions of small volume, and the rate of analysis is similar to that achieved with other semi-automated analyzers.
Arsine Ascorbic acid Electrode

"Single-point Titration. 4. Determination Of Acids And Bases With Flow Injection Analysis"
Anal. Chim. Acta 1979 Volume 105, Issue 1 Pages 67-75
Ove &Aring;str&ouml;m

Abstract: A single-point titrimetric system for acids and bases based on the flow injection principle is reported. The 30 µL sample is introduced into a water stream with a pneumatic injector; this stream is recorded potentiometrically with a glass electrode in a flow-through cell. The peak maxs. are a linear function of the acid or base concentration. in the range 0.01-0.1M. At a sampling rate of 180 samples/h, the relative deviation is <1%. The method can be used at sampling rates as high as 720 samples/h.
Acids Bases Potentiometry Electrode

"Determination Of Water By Flow Injection Analysis With The Karl Fischer Reagent"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 199-208
Ingrid K&aring;gevall, Ove &Aring;str&ouml;m and Anders Cedergren

Abstract: A method for the determination of water in organic solvents by flow-injection analysis (f.i.a.) is described. The method, which is based on the reaction between water and the Karl Fischer reagent, is capable of 120 determinations per hour. The concentration range 0.01-5% (v/v) of water can be covered by using a single Karl Fischer reagent solution. The results obtained with a specially constructed potentiometric detector showed a relative standard deviation of less than 0.5% (v/v). This value was about 3 times less than that obtained with a spectrophotometric detector. The f.i.a. technique is shown to offer some unique possibilities in minimizing interferences associated with the standard Karl Fischer batch titration method.
Water Organic compound Organic compound Industrial Karl Fischer analysis Potentiometry

"A Modeling Approach To Establish Experimental Parameters Of A Flow-through Titration"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 235-246
H. F. R. Reijnders and J. F. Van Staden, G. H. B. Eelderink, B. Griepink

Abstract: A flow-through titrimeter with optical detection and the flow-through titration of sulphate have been studied by using control engineering methods. Qualitative chemical descriptions and systems analysis yield a model covering different precipitation rates of barium sulphate. The validity of the model is proved by comparing simulated and real experiments. Possible uses of the model are indicated. The signal of the titrimeter is shown to be independent of dilution and turbidity, because of the special detection arrangement.
Sulfate Water Spectrophotometry Turbidimetry

"Controlled Dynamic Titrator"
Anal. Chim. Acta 1980 Volume 114, Issue 1 Pages 247-256
S. M. Abicht*

Abstract: The controlled dynamic titrator described operates with constant titrant flow and time-proportional sample flow; sample and titrant are mixed in a microcell and the equivalence point is reached when the products of the normalities and flow rates of the titrant and the sample are equal. Titration times are measured and printed out. The concentration of the sample is inversely proportional to the titration time. The automatic titrator is discontinuous and suitable for on-line and off-line use. The cycle time of the motor-driven programmer is 2 min. Flow-through detectors for potentiometric, photometric or voltammetric indication can be used for a selection of acid-base and redox titrations. With this equipment, titration of large series of liquid samples with similar contents is simple.
Potentiometry Spectrophotometry Voltammetry

"Comparative Study On The Precision Of Potentiometric Techniques Applied With Ion-selective Electrodes. 3. Potentiometric Titrations"
Anal. Chim. Acta 1980 Volume 116, Issue 1 Pages 87-92
G. Horvai and E. Pungor

Abstract: Mathematical descriptions of potentiometric titration curves are considered. Methods for calculations of titration errors are discussed with particular reference to single-point and Gran methods of titration.
Electrode Potentiometry

"Determination Of Sulfur Dioxide In Solutions By Pyridinium Bromide, Perbromide, And Titrimetric And Flow Injection Procedures"
Anal. Chim. Acta 1981 Volume 123, Issue 1 Pages 351-354
T. R. Williams, S. W. McElvany and E. C. Ighodalo

Abstract: Sulfur dioxide can be determined by its reaction with pyridinium bromide perbromide using photometric titrations and flow injection procedures. Both methods are useful down to 30 ppm, and are unaffected by ammonia or nitrogen dioxide. Both mercury(II) and EDTA interfere under some circumstances.
Sulfur dioxide Environmental Spectrophotometry

"Kinetic Treatment Of Unsegmented Flow Systems. 1. Subjective And Semiquantitative Evaluations Of Flow Injection Systems With Gradient Chamber"
Anal. Chim. Acta 1981 Volume 124, Issue 1 Pages 39-63
Harry L. Pardue and Bernard Fields*

Abstract: A variable-time kinetic model is used to evaluate a single-channel flow-injection system with gradient chamber that has been identified as a continuous-flow titration. A physical model, mathematical equations, computed concentration vs. time profiles, experimental data, and formal definitions are used to identify qualitative and quantitative features of the method that have not been apparent from the titration model for the system. It is shown that determinations can be performed with and without reactant in the flow stream and when reactant is in the flow stream, with and without reactant in the gradient chamber when the sample is introduced. It is shown that lowest concentrations with shortest cycle times can be achieved when determinations are performed without reagent in the gradient chamber initially. Characteristics unique to each of three different data processing options are used to evaluate the validity of equations presented. It is suggested that some methods previously identified as continuous-flow titrations are most accurately identified as variable-time kinetic methods, and it is shown that this semantic differentiation can provide improved insight into the methods and can expand the scope of the methods by suggesting new experimental approaches with potential advantages relative to previously described procedures.

"The Principles And Theory Of High-speed Titrations By Flow Injection Analysis"
Anal. Chim. Acta 1981 Volume 129, Issue 1 Pages 1-17
A. U. Ramsing, J. Rika and E. H. Hansen

Abstract: The highly reproducible concentration gradients formed between an injected sample zone and the carrier stream in flow injection analysis are exploited for titrations based on measuring the time span between points of identical gradient dispersion. Comparison of the experimental data with theoretical models, has made it possible to locate the position and physical dimension of a single mixing stage, which at medium dispersion of the sample zone allows the entire titration cycle, including sampling and washout periods, to be completed within less than 30 s. The capability of this high-speed titration technique is demonstrated for acid-base, complexometric and iodometric titration procedures.

"A Sensitive And Accurate Automatic Coulometric Detector System For Enzymatically Produced Carbon Dioxide"
Anal. Chim. Acta 1981 Volume 131, Issue 1 Pages 133-139
Anders O. Lindberg

Abstract: A system for the determination of carbon dioxide liberated in an enzyme reactor is described. The properties of the system are illustrated by the determination of urea. Enzymatically generated carbon dioxide is expelled by boiling, dried and determined coulometrically. The lowest concentration of urea which can be determined with a relative standard deviation of 5% is 1 M. Compared with other methods based on immobilized enzymes for the determination of compounds as carbon dioxide, this sensitivity constitutes an improvement of about two orders of magnitude. Possible application to sea water is discussed.
Carbon dioxide Urea Water Coulometry

"Minimization Of Interference Effects From Iodine-consuming Samples In The Determination Of Water With The Karl Fischer Reagent In A Flow Injection System"
Anal. Chim. Acta 1981 Volume 132, Issue 1 Pages 215-218
Ingrid K&aring;gevall, Ove &Aring;str&ouml;m and Anders Cedergren

Abstract: A principal feature of the flow-injection approach for determination of water with the Karl Fischer reagent is the small influence of side reactions. This is confirmed by the determination of water in an iodine-consuming sample, penicillin (fugacillin).
Water Pharmaceutical Industrial Karl Fischer analysis Spectrophotometry

"Flow Injection Analyzer For Students, Teaching And Research. Spectrophotometric Methods"
Anal. Chim. Acta 1982 Volume 134, Issue 1 Pages 55-71
J. Rika, E. H. Hansen and A. U. Ramsing

Abstract: The flow streams in simple manifolds are propelled by controlled gas pressure; ancillary equipment consists of a small spectrophotometer or colorimeter and a chart recorder. The analytical result is available in less than 20 s after sample injection, with a reproducibility better than 1%, using microlitre volumes of sample and less than millilitre volumes of reagent per assay. These are the performance data of a simple, robust and inexpensive flow injection analyzer designed for use with a wide range of detectors. The application spectrophotometry is illustrated by five exercises aimed at teaching instrumental analysis and intended for those who wish to introduce flow injection analysis in their laboratories.
Calcium Chloride Chromium(VI) Fluorescence Luminescence Potentiometry Spectrophotometry

"Automatic Potentiometric Two-phase Titration In Pharmaceutical Analysis. 1. The Influence Of Ionic Surfactants On Some Protolytic Equilibria In The Aqueous Phase"
Anal. Chim. Acta 1982 Volume 140, Issue 1 Pages 77-88
Per-Arne Johansson, Gun Hoffmann and Ulf Stefansson

Abstract: The autoprotolysis constant of water is shown to be unaffected by the presence of 0.05 M hexadecylpyridinium chloride (HPC) and an organic phase (dichloromethane). In the presence of 0.05 M sodium dodecyl sulphate (SDS), however, the pH scale is shortened by about 0.2 units because of the formation and solubilization of dodecyl sulphuric acid. Constants for the distribution of some amines (lidocaine, prilocaine and tocainide) between an aqueous phase and a micellar phase of HPC are reported, as is the equilibrium constant for the extraction of the lidocaine/dodecyl sulphate ion pair into a micellar phase of SDS.
Anions Pharmaceutical Potentiometry

"Recent Developments In Flow Injection Analysis: Gradient Techniques And Hydrodynamic Injection"
Anal. Chim. Acta 1983 Volume 145, Issue 1 Pages 1-15
J. Rika and E. H. Hansen

Abstract: Some of the most exciting recent advances in flow injection analysis (f.i.a.) have involved gradient techniques, which, founded on the key role of the dispersion controlled in space and time, are based on the feasibility of identifying and selecting reproducibly suitable sections of the dispersed sample zone and exploiting the specific concentrations at these points for analytical purposes. A comprehensive review of these techniques is given; in addition to the well established f.i.a. titrations and stopped-flow reaction rate procedures, methods have been developed for gradient dilution and calibration, gradient scanning, and selectivity evaluation. Finally, a detailed description of the most recent development within f.i.a., a hydrodynamic injector with no moving parts and zero dead volumes, is presente.
Spectrophotometry

"Flow Injection Single-point Titration Of Acids With Biamperometric Detection At Polarized Platinum Electrodes"
Anal. Chim. Acta 1987 Volume 194, Issue 1 Pages 269-274
Wojciech Matuszewski, Adam Hulanicki and Marek Trojanowicz

Abstract: Samples of acids (15 µL) were injected into a stream of water which was merged with a stream of 2 M NaI and 50 mM NaIO3 (2.4 mL min-1). The detector placed 10 cm from the merging point was a flow cell containing two 8-mm x 0.3-mm diameter platinum electrodes at a constant polarizing voltage of 100 mV. Rectilinear graphs of concentration. vs. current were obtained for 1 to 10 mM acid and, with online microcomputer data processing, a coefficient of variation <0.2% was achieved.
Acids Acetic acid Formic acid Hydrofluoric acid Monochloroacetic acid Sulfuric acid Biamperometry Electrode

"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

"Device For Stepwise Addition Of Titrant In Automated Potentiometric Titrations"
Anal. Chim. Acta 1989 Volume 222, Issue 2 Pages 379-384
B. F. Reis, O. E. S. Godinho, L. M. Aleixo and J. J. R. Rohwedder

Abstract: The cited microcomputer-based device is driven by a 20-V, 18-W DC motor reduced to operate at 26 rpm, and can deliver to up to six titration cells simultaneously. Titrants are received into and delivered from 1 mL plastic syringes under control of a commutator similar to that used in flow injection analysis. In titrations of 0.01 M HCl (24.95 ml) with 0.1 M NaOH in the presence of 0.1 M KCl, with use of glass and calomel or double-junction reference electrodes, the coefficient of variation (two sets of three simultaneous titrations) was 0.1% and the relative error with respect to the theoretical equivalence volume was +0.2%.
Potentiometry

"Direct Automatic Determination Of Free Acidity In Oils By Flow Injection Analysis"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 431-436
P. Linares, M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: The sample is mixed with ethyl ether - ethanol (1:1) flowing at 1.5 mL min-1, and this is mixed with ethanolic 50 mM KOH - 0.01% phenolphthalein (0.9 mL min-1) and then with a second similar reagent stream. After passage through a 250-cm reaction coil, the decrease in absorbance of the mixture is measured at 562 nm. Peak heights are measured for low concentration. (0.15 to 0.81%) and peak widths or flow injection titration is used for higher concentration. (4.04%). The sampling rate is 60 h-1. Results agreed with those of the standard method.
Acidity Oil Spectrophotometry

"Quantitative Validation Of A Flow Injection Determination Of Penicillin In Pharmaceutical Formulations By Means Of A Validation Program Based On An Expert System"
Anal. Chim. Acta 1990 Volume 233, Issue 1 Pages 65-76
R. Wolters, M. A. J. van Opstal and G. Kateman

Abstract: A generally applicable validation program, VALID, based on an expert system program is described. The automated penicillin assay was performed by enzymatic hydrolysis of penicillin to penicilloic acid, which reacts with iodine generated online. The iodine consumption was measured by using an amperometric detector (cf., Kok et al., Ibid. 1984, 162, 19). During the program run, the system evaluated the calibration procedure, the drift of the analytical system and the effect of the sample matrix. The reliability of the flow injection method was estimated by evaluating the max. total error, which includes random and systematic errors. The latter was assessed by comparing the results with those obtained by titration with Hg(II). The user requirement for the assay was a max. total error of 10%. The validation procedure showed that the analytical method complied with the requirements for the major part of the concentration. range of 66 to 250 µM.
Penicillin Pharmaceutical Amperometry

"Application Of Wet Chemistry Techniques To Process Analysis And Control"
Anal. Chim. Acta 1990 Volume 238, Issue 1 Pages 161-170
Rajko Puzic

Abstract: The application of automatic titrators and ion chromatographs to the compositional analysis of caustic and alkanolamine gas sweetening solution is described. Comparisons with other techniques such as flow injection analysis and UV and near-IR spectrometry are made and pertinent features and benefits of each are discussed.
Gas HPIC

"Amperometric Determination Of Hydrogen And Hydroxy Ion Concentrations In Unbuffered Solutions In The PH Range 5 To 9"
Anal. Chim. Acta 1991 Volume 243, Issue 1 Pages 55-59
G. Horvai and E. Pungor

Abstract: The cited determination was performed with use of a dual-channel flow injection system. The LC amperometric detector was equipped with a large-volume wall-jet cell containing a H+-selective working electrode, which comprised a plasticized PVC membrane loaded with tridodecylamine (prep. described) and filled with 1 mM HCl - 0.1 M KCl into which was immersed a Ag - AgCl reference electrode. A Pt wire was used as the counter electrode. The sample solution, injected into water in one channel of the system, was mixed with 0.1 M NaCl from the second channel; flow rates were 1.05 mL min-1. Both H+ and OH- were determined from 1 to 10 µM. Satisfactory selectivity with respect to several common cations and anions was demonstrated. The flow injection amperometric method was also used for flow acid - base titrations.
Acidity Hydroxide Amperometry LC Electrode Electrode

"Determination Of Microgram And Nanogram Amounts Of Active Chlorine In Water By Iodine - Azide Reaction Induced By Thiosulfate Or Thioammeline"
Anal. Chim. Acta 1991 Volume 252, Issue 1-2 Pages 127-132
Jan Kurzawa*, Zbigniew Kurzawa and Krystyna Janowicz

Abstract: An indirect determination of active Cl in water is described based on the iodine - azide reaction and measuring the amount of thiosulfate (I) or thioammeline (II) oxidized by Cl is described. Three methods based on this principle were applied, viz, back-titration of excess iodine, titration with an iodine reagent and continuous-flow amperometric detection of the released iodine. The working ranges for the determination of Cl by back-titration were 0.2 to 2.4 and 0.02 to 0.14 µg mL-1 in the presence of I and II, respectively, by titration were 0.3 to 2 ng mL-1 in the presence of II and by continuous-flow determination were 0.5 to 5 µg L-1 and 0.05 to 1.5 mg L-1 depending on the reaction conditions and inductor used.
Chlorine, active Water Amperometry

"Rapid PK Measurements For Multibasic Weak Acids By Gradient Flow Injection Titration"
Anal. Chim. Acta 1992 Volume 258, Issue 2 Pages 259-267
David R. Turner*, Margarida M. Correia dos Santos, Paulo Coutinho and Maria de Lurdes Gon&ccedil;alves, Susan Knox

Abstract: The pK values of phthalic acid, phosphoric acid and EDTA (pK2, pK3 and pK4 only) were determined by rapid gradient flow injection titration Key factors in experimental design was investigated, viz. pH range of the titration, direction of titration, flow-rate and weak acid concentration. Under optimum conditions, the technique is well suited to the determination of pK values with a precision of 0.01-0.05 pK and in good agreement with literature values. It is less well suited than conventional batch titration to the determination of very low or high pK values at low weak acid concentrations.
Phthalic acid Phosphoric acid EDTA Acids, weak

"Development Of A Micro Flow Spectrophotometric Titration Method"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 505-508
Fumio Segara*, ToshiyukiKobayashi, Tadayoshi Tajima, Hiroyuki Ijyuin, Isao Yoshida, Daido Ishii and Keihei Ueno

Abstract: A µflow spectrophotometric titration method is described. Commercially available flexible fused-silica capillary tubes for gas chromatography were found to have very uniform bore and good flexibility, and could be used for constructing microburettes, micropipettes and micro-flow cells. A solution of less than 120 µL in a microbeaker (500 µL) was titrated with EDTA solution from a microburette. The solution in the beaker was circulated through the micro-flow cell of a spectrophotometric detector to determine the indicator end-point. The dead volume of the circulating system was about 75 µL. For example, a solution (about 100 µL) containing 1.31 µg of zinc, buffer (pH 5.21) and Xylenol Orange indicator was titrated with 0.02 M EDTA solution, the volume of titrant was as small as 0.94 µL.
Zinc Spectrophotometry

"Automatic Titrations In Unsegmented Flow Systems Based On Variable Flow-rate Patterns. 2. Complexometric And Redox Titrations"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 495-503
J. Marcos, A. R&iacute;os and M. Valc&aacute;rcel*

Abstract: Variable flow-rate patterns were used to develop automatic complexometric and redox titration procedures in unsegmented continuous-flow systems. Complexometric titrns. were carried out by using EDTA as titrant and were applied to single and simultaneous determinations of several metal ions with colored indicators (spectrophotometric monitoring). Ascorbic acid was also determined by this procedure using N-bromosuccinimide as titrant and iodine-starch as indicator. The methods thus developed were applied to the anal. of real samples.
Metals Ascorbic acid Spectrophotometry

"Automatic Titrations In Unsegmented Flow Systems Based On Variable Flow-rate Patterns. 1. Principles And Applications To Acid-base Titrations"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 489-494
J. Marcos, A. &iacute;os and M. Valc&aacute;rcel*

Abstract: Automatic acid-base titrations were carried out by generating pH gradients in a continuous-flow manifold. A programmable, computer-controlled pump was used to produce variable, reproducible flow-rate patterns that were used to increase gradually the titrant concentration in the flow system. A colorimetric indicator reagent allowed the spectrophotometric detection of the equivalence point. Strong and weak acids, both alone and in mixtures, and two protons of the same acid were titrated with a relative standard deviation of 1.8%. The procedure was applied to the analysis of various real samples.
Acids Bases

"Automated Continuous-flow Titration"
Anal. Chim. Acta 1992 Volume 269, Issue 1 Pages 29-34
Jordi Bartroli* and Lloren&ccedil; Alerm

Abstract: A piston burette is used to inject varying volume of a solution in order to perform continuous-flow titration of samples. The system is demonstrated using acid - base titration with a pH electrode to monitor changes. A plot of peak height vs. volume of acid or base added provides a titrimetric graph from which the equivalence point can be precisely determined. The advantage of the piston burette is in its ability to dispense small volume precisely and reproducibly. An automated continuous titration method is described in which the use of a piston buret as a variable-volume injection device in a flow system allows a continuous-flow titration of a sample solution to be performed similarly to classical batch titrimetric procedures. It is found that by plotting the peak height for each injection vs. the titrant volume injected, a titration curve very similar to a batch titrimetric curve can be obtained, and an equivalence volume can be precisely determined A linear relationship between the logarithm of the equivalence volume and the logarithm of the carrier concentration has been observed over a wide concentration. range. The use of reagent is kept to a min. because titrations are performed by addition only microliters of reagent. The time required for the titration is comparable to the time consumed by a process titration system.

"Triangle Programmed Coulometric Flow Titration With Potentiometric And Optical Detection"
Anal. Chim. Acta 1993 Volume 273, Issue 1-2 Pages 521-530
Zs&oacute;fia Feh&eacute;r*, G&eacute;za Nagy, Istv&aacute;n Slezs&aacute;k, Kl&aacute;ra T&oacute;th and Ern&ouml; Pungor

Abstract: The application of a flow-through titration technique, the so-called triangle programmed coulometric titration, is presented for acid-base titrations using potentiometric and photometric detection. A flow-through capillary glass electrode-saturated calomel electrode pair was employed for potentiometric detection, and an indicator mixture and a light-emitting diode-phototransistor system was used for photometric detection. In photometric detection the precision of the end-point location was enhanced by the addition of a suitable mixture of Methyl Red and m- Cresol Purple acid-base color indicators. The suitability of the technique was demonstrated for different acid-base titrations. As an example, the determination of the drug content of a nicotinic acid-containing experimental pharmaceutical preparation is described.
Potentiometry Coulometry

"Volumetric Triangle-programmed Flow Titrations Based On Precisely Generated Concentration Gradients"
Anal. Chim. Acta 1993 Volume 282, Issue 2 Pages 397-406
B. Fuhrmann and U. Spohn

Abstract: Linear concentration gradients were generated by means of computer-controlled micropumps, to implement triangle-programmed flow titrations. Precise determinations could be Performed under defined conditions without calibration. The use of inverse flow-rate gradients enables volumetric titrations to be Performed in constantly flowing streams. The mixing of flow-rate gradients of the titration reagent and the sample solution, which are inverse to each other, opens up a way to titrate samples with concentrations varying over several orders of magnitude. The zone sampling out of precisely defined triangle concentration profiles and the injection into a continuously streaming sample or standard solution opens up a way to methods of flow injection analysis (FIA) with improved reliability and online calibration. The titrations and the FIA procedures are controlled and analyzed automatically by a personal computer. A compact and fully automated flow titrator was developed. [References: 26]

"Rapid Determinations Of Complexing Stability Constants By Gradient Flow Injection Titration"
Anal. Chim. Acta 1995 Volume 302, Issue 1 Pages 97-102
A. C. Lopes da Concei&ccedil;&atilde;o, M. L. S. Sim&otilde;es Gon&ccedil;alves* and M. M. Correia dos Santos

Abstract: The equilibrium constants for the cadmium-glycine system were determined by gradient flow injection (FI) titration using potentiometric detection with a glass electrode. In gradient FI titrations, the injection valve is switched once and the transition between carrier and sample solution is monitored following dispersion in a gradient chamber. In this way, a simulation of a titration is carried out in a few minutes. For the model system studied, titration graphs were prepared in the pH range 7.7-8.8 using different pairs of solutions to cover different concentration ranges of the metal and ligand. The formation constants for the complexes ML and ML2 of Cd2+ with glycine were then calculated by non-linear least squares regression analysis. The results were in agreement with those obtained by batch titration measurements and also with literature values. The use of rapid gradient flow-injection titration for the determination of equilibrium constants in solution, previously used in pK measurements of monobasic and multibasic weak acids is extended to the more demanding case of metal complexation. Formation constants for the complexes ML and ML2 of Cd2+ with glycine have been determined by that technique using potentiometric detection with a glass electrode. Under optimum conditions formation constants in good agreement with batch and literature values are obtained in several minutes.
Cadmium Glycine Potentiometry

"Linear Flow Gradients For Automatic Titrations"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 67-76
I. L&oacute;pez Garc&iacute;a, P. Vi&ntilde;as, N. Campillo and M. Hern&aacute;ndez C&oacute;rdoba*

Abstract: A manifold was described to perform automatic continuous-flow titrations. A variable-speed peristaltic pump (pump A) was employed to deliver the titrant at a linearly increasing flow rate. A second pump working at constant and higher speeds was positioned after the detector cell and was used to draw titrand into the stream and produce a constant flow rate through the detector cell. A third pump working at constant speed was used to add indicator solution to the stream. The steam passed though a mixing coil (1 m x 0.5 mm i.d.) before passing to the spectrophotometric detector cell (8 µL volume). The titrations were performed by increasing the speed of pump A from zero to maximum and then back to zero. In this way two equivalence points were obtained and the difference in time between them was used to calculate the analyte concentration. The technique was evaluated with acid-base and complexometric titration. HClO4 was titrated with NaOH using phenolphthalein (550 nm) and bromothymol blue (615 nm) as indicators and Zn(II)-EDTA titration were carried out with xylene orange indicator (430 nm). The time differences between the two equivalence points agreed with those predicted by theory and errors were ±2%.
Sulfuric acid Zinc Spectrophotometry

"Determination Of Sulfuric Acid In Metallurgical Process Streams By Discontinuous Flow Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 197-205
Terence J. Cardwell, Robert W. Cattrall, Graeme J. Cross, Gregory R. O'Connell, John D. Petty and Geoffrey R. Scollary

Abstract: The determination of H2SO4 in metallurgical process solutions was based on photometric titration with 0.2 M sodium acetate using bromophenol blue (BPB) indicator. The fully automatic discontinuous flow analyzer. was equipped with a high-intensity yellow light emitting diode (λmax = 585 nm) and a phototransistor. A 0.5 g/l BPB indicator solution was used. The sample volume was 900 µL and the titrations were completed in ~e;33 s. The method exhibited excellent repeatability and reproducibility with RSD of 1%. The method was applied to the analysis of solutions taken from Cu, Mn and Zn refining plants. As(V) and Fe(II) were found to interfere with the determination to a significant extent. High levels of Cd, Cr(III), Cu(II) and Pb(II) resulted in small positive errors while Ca, Co(II), Mg, Mn(II), Ni(II) and Zn did not interfere.
Sulfuric acid Process liquor Spectrophotometry

"Continuous-flow Titration System For The Generation Of Multivariate Spectrophotometric Data In The Study Of Acid-base Equilibria"
Anal. Chim. Acta 1995 Volume 312, Issue 2 Pages 189-198
J. Saurina, S. Hern&aacute;ndez-Cassou* and R. Tauler

Abstract: In the present work a continuous flow system to carry out spectrophotometric titrations is developed. The titrant solution is generated on-line from mixing two different stock buffer solutions. The composition of the titrant agent is sequentially varied along the titration by changing the ratio of flow rates of both buffer channels, and therefore the pH can be modified. One spectrum is recorded at each pH value when the absorbance achieves the steady state. The spectral data have been treated by means of a recently developed self-modelling multivariate curve resolution method (SPFAC procedure). This method has been applied to the study of the acid-base equilibria of 1,2-naphthoquinone-4-sulfonate (NQS). Four titrations with concentrations of NQS ranging from 1.6 x 10^-4 to 7.3 x 10^-4 M have been performed, and, in every case, 24 spectra at different pH have been registered. Three species are detected in the range of pH studied (6.9-12.3). Their distribution plot with pH and their unit spectrum have been obtained.
Acids Bases Spectrophotometry

"Binary Search In Flow Titration Employing Photometric End-point Detection"
Anal. Chim. Acta 1995 Volume 313, Issue 3 Pages 177-184
Mauro Korna, Luis F. B. P. Gouveiab, Elisabeth de Oliveirac and Boaventura F. Reisd,*

Abstract: A binary search strategy is proposed and implemented in a continuous flow system to find the end-point titration by employing spectrophotometric detection. It takes advantage of the binary sampling process under a constant flow-rate. For this task an automated flow set-up based on solenoid valves was designed. A 386 microcomputer was employed to control the valves, and to perform data acquisition and data processing. The accuracy level can be previously settled as a software parameter. Samples with concentrations ranging within two orders of magnitude could be titrated by making use of the same flow set-up. Titration of hydrochloric acid with sodium hydroxide was performed to demonstrate the feasibility of the proposal. Titrations in triplicate, with 99.99% precision were carried out in 3 min with a solution consumption of 2 mL.
Spectrophotometry

"Selective Determination Of Gas Dialysable Components In Complex Sample Solutions Using Triangle Programmed Coulometric Titration In Continuous-flow Systems"
Anal. Chim. Acta 1996 Volume 324, Issue 2-3 Pages 115-123
M. Becker, B. Fuhrmann and U. Spohn*

Abstract: A method is described for determining ammonium/NH3 and sulfide/hydrogen sulfide in leachate from a municipal waste land-fill site. Sample (0.1 ml/min) was merged with a conditioning stream (0.1 ml/min) of 0.1 M NaOH (for ammonium/NH3) or 0.1 M HCl (for sulfide/hydrogen sulfide) and the mixture was propelled through the donor channel of a dialysis cell. The generated NH3 and H2S were adsorbed into acceptor streams (0.2 ml/min) of 0.1 M KBr/0.1 M sodium borate of pH 8.3 or 0.1 M KBr/0.1 M NaHCO3, respectively, and titrated with electrogenerated hypobromite produced at Pt electrodes by the oxidation of bromide. After the oxidations of NH3 and H2S, the remaining bromine was detected amperometrically at a Pt electrode (0.18 V) and the remaining hypobromite was detected by chemiluminescence via its reaction with 20 µM-luminol (2 ml/min). For ammonium/NH3, the linear ranges were 10 µM-10 mM with amperometric detection and 1 µM-0.5 mM with chemiluminescence detection and RSD (n = 6) were 3%. The linear range for sulfide/H2S was 0.2 µM-0.5 mM with chemiluminescence detection and the RSD (n = 6) was 4%. The sampling frequency was 30 samples/h.
Ammonium Sulfide Waste Coulometry Amperometry Electrode Chemiluminescence

"Study Of Equilibria In Cyanide Systems By Gas Diffusion Measurement Of Hydrogen Cyanide"
Anal. Chim. Acta 1996 Volume 336, Issue 1-3 Pages 131-140
Jamal A. Sweileh

Abstract: Speciation of hydrogen cyanide in different metal-cyanide systems at the µg mL-1 level was established by the selective measurement of hydrogen cyanide (HCN) diffused through a microporous Teflon membrane under thermodynamic equilibrium conditions. The test solution was continuously aspirated through the donor side of the gas diffusion unit until equilibrium was achieved with the stagnant buffer solution on the receptor side. The final assay of HCN was carried out spectrophotometrically (chloramine-T/barbiturate/isonicotinate) in the flow injection mode. The theoretical relation between the enrichment factor and the pH of the donor and receptor solutions was derived and experimentally verified. As confirmed by calculation the speciation of HCN can be established for simple soluble cyanides and cyanide complexes with log formation constants as high as 20. For more stable cyanide complexes the results are satisfactory; but for the highly stable hexacyanoferrate(III) this method is not feasible. The speciation of cyanide in metal-cyanide systems was studied by measuring the HCN concentration using a gas diffusion cell incorporated into a flow injection spectrophotometric system. The metal-cyanide test solution was pumped (2 ml/min) through the donor channel of the gas diffusion cell for 6 min until equilibrium was reached. During this period the acceptor solution, 0.1 M NaH2PO4 of pH 7, was kept stationary. At the end of the sampling period, the acceptor solution was injected into a carrier stream (0.4 ml/min) of 0.1 M NaH2PO4 of pH 7 and merged with 0.01% chloramine-T (0.4 ml/min) and sodium barbiturate/sodium isonicotinate reagent (1.6 ml/min). The mixture was heated to 68°C and propelled to the detection cell where the absorbance was monitored at 600 nm. The acceptor and donor channels of the gas diffusion cell had volumes of 0.108 mL. The apparatus was calibrated with 0.1-1 µg/ml NaCN. The calibration graph was linear, the detection liwas 0.025 ng/ml and the RSD (n = 9) for 0.5 µg/ml cyanide was 0.6%. The method was applied to metal-cyanide complexes at various pH values from 2-11. At each pH the concentration of each species was calculated using two mass balance equations, one for total cyanide and the other for total metal. 19 References
Hydrogen cyanide Spectrophotometry

"Selective Determination Of Protolytes By Flow Injection Analysis. A Guide For The Rational Selection Of Reagent Composition"
Anal. Chim. Acta 1997 Volume 344, Issue 3 Pages 271-280
Fernando Albert&uacute;s*, Isel Cort&eacute;s, Lars G. Danielsson and Folke Ingman

Abstract: The measurement of the concentration of a strong acid or base in the presence of a weaker one is described. A systematic methodology for selecting a reagent mixture for the spectrophotometric determination of protolytes by FIA is proposed. A theoretical study was performed of the instantaneous equilibria obtained at the peak maximum when two protolytes injected into the carrier merge and react with a buffer/indicator stream. The strength and concentration of the buffer required to neutralize the stronger component without reacting with the weaker one were deduced. Guidelines are given for the selection of an indicator for combination with a preselected buffer. Synthetic and real samples of acid and alkaline mixtures were analyzed and the results were compared with those obtained by potentiometric titration.
Acids Bases Spectrophotometry Potentiometry

"Automated Flow Injection Spectrophotometric Non-aqueous Titrimetric Determination Of The Free Fatty-acid Content Of Olive Oil"
Anal. Chim. Acta 1997 Volume 351, Issue 1-3 Pages 291-297
Panayotis G. Nouros, Constantinos A. Georgiou and Moschos G. Polissiou*

Abstract: An automated how injection titrimetric method for the determination of olive oil acidity is proposed. A 175 µl olive oil aliquot is injected in a carrier stream (the titrant) of n-propanol containing 7.5 x 10^-4 M KOH and 4.0 x 10^-5 M phenolphthalein indicator. The sample zone is dispersed in the titrant while flowing at 4.4 mi min-1 through a 1.1 mi Plexiglas mixing chamber and the absorbance of the resulting mixture is continuously monitored at 562 nm, lambda(max), for the basic form of the indicator. The resulting negative absorbance peaks indicate the transition base (red)-acid (colorless)-base (red) of the indicator. Quantitation is based on peak width measurements. Peak widths of 31.7-97 a were measured with a relative standard deviation (RSD) of < 2.1% (n = 10), and the analytical range was 0.15-8.0% (w/w) free fatty acid content calculated as oleic acid. The sampling rate is 30-100 h-1 while n-propanol consumption is only 3-7 mi per run. Recoveries of oleic acid from commercial olive oils ranged from 97.9 to 101.6% (mean 99.5%). The method was applied for the determination of free fatty acid content of thirty two samples of olive oils. Results obtained by the proposed method compare well (0.3-3.6% relative difference, mean 1.5%) with those obtained by the official European Community method that is time consuming and uses gross amounts of organic solvents. Moreover comparison with a Fourier transform infrared F-IR) method reveals that by using the proposed method the useful range can be extended to lower concentrations. 18 References
Fatty acids, free Oil Spectrophotometry

"Time-division Multiplex Technique For Producing Concentration Profiles In Flow Analysis"
Anal. Chim. Acta 1998 Volume 368, Issue 1-2 Pages 105-111
Xue D. Wanga, Terence J. Cardwella, Robert W. Cattralla,*, Robert P. Dysonb and Graeme E. Jenkinsc

Abstract: A technique is described that uses computer-controlled solenoid valves for creating concentration. profiles for various flow-based methods of anal. These profiles can be quickly selected through software and, similarly, parameters such as the volume of the sample, carrier, and reagents can be set and altered when required, with minimal changes to the hardware. The technique has been demonstrated for flow titration and flow injection but is equally applicable to other methods. In all these methods, only a single channel pump is required to draw the mixed solutions through the detector, and individual solutions are introduced into the flowing stream by selection through solenoid-operated valves. Results are presented for the determination in water samples of calcium using potentiometric titration and orthophosphate by flow injection using the molybdenum blue method. The technique uses only small volumes of solutions and is fully automated and so is ideal for use in portable instrumentation.
Calcium Phosphate Environmental Potentiometry Spectrophotometry

"Automated Flow Injection Pseudotitration Of Strong And Weak Acids, Ascorbic Acid And Calcium, And Catalytic Pseudotitrations Of Aminopolycarboxylic Acids"
Talanta 1985 Volume 32, Issue 5 Pages 411-417
M. A. Koupparis* and P. AnagnostopoulouH. V. Malmstadt

Abstract: An automated spectrophotometric system applicable to acid - base, redox, complexometric and catalytic titrations is described. Peak widths (in time units) from 10 to 100 s can be measured with coefficient of variation of <0.3%. Strong and weak acids, both 0.5 to 20 mM, were titrated with NaOH in presence of bromothymol blue, ascorbic acid (0.1 to 10 mM) with 2,6-dichlorophenolindophenol and Ca (0.5 to 50 mM) with EDTA - Mg(II) complex and calmagite as indicator. Aminopolycarboxylic acids, EDTA and similar compounds (5 µM to 10 mM) were measured by monitoring at 470 nm the product of the manganese-catalyzed periodate diethylaniline reaction. The proposed method was applied to the determination of total hardness in water and to the determination of ascorbic acid in various pharmaceuticals.
Acids Ascorbic acid Calcium Hardness Pharmaceutical Environmental Spectrophotometry

"Flow-reversal Flow Injection Analysis. Enhancement Of Flow Injection Titrations"
Talanta 1991 Volume 38, Issue 2 Pages 119-124
Gregory D. Clark, John Zable, Jaromir Rika and Gary D. Christian*,

Abstract: Developments in flow-reversal flow injection analysis are discussed. Repetitive reversal of flow is used for various purposes, such as increasing the time of flow between sample injection and detection, increasing sample dispersion and increasing extraction efficiency. Flow programming allows flexibility in operation without the need to change manifolds. Use of flow-reversal in flow injection analysis titrations increases sensitivity.
Sample preparation

"Simultaneous Determination Of Calcium And Magnesium By Using A Flow Injection System With Simultaneous Injection Of Two Sample Plugs And A Masking Agent Plug"
Talanta 1991 Volume 38, Issue 2 Pages 139-143
Takeshi Yamane* and Eiichi Goto,

Abstract: Two sample plugs were injected into a carrier stream of water, one plug was mixed with a plug of 10 mM EGTA in dilute aqueous NH3 to complex Ca. The carrier steam was merged with 0.05% of 3,3'-bis-[NN-bis(carboxymethyl)aminomethyl]-o-cresolphthalein in aqueous NH3 - NH4Cl buffer of pH 10.1 (0.5 mL min-1) then passed through a 1-m reaction coil before detection at 575 nm. One peak corresponds to Mg and the other to Mg plus Ca; Ca was determined by difference. Calibration graphs were rectilinear for at least 30 µg mL-1 of Ca or Mg. Phosphate, citrate and oxalate interfered at concentration. of ~0.5 mg mL-1. Analysis rate was 15 samples h-1. Results from the analysis of ground, river and seawater agreed well with those obtained by titration with EDTA.
Calcium Magnesium Ground River Sea

"Flow Injection Coulometric Titrations"
Talanta 1992 Volume 39, Issue 3 Pages 285-292
Richard H. Taylor, Jaromir Rika* and Gary D. Christian*,

Abstract: The system comprised a gradient chamber, a reagent-generation chamber and a detector flow cell, to and from which light was transmitted by optical fibers (illustrated). The method was demonstrated by the titration of 0.5 mM to 4 M NaOH and 5 mM to 15 M HNO3 with a carrier of 0.5 M Na2SO4 containing 0.04% of bromothymol blue as indicator. The coefficient of variation (n 3) were from 0.3 to 2.9%. A flow injection analysis technique based on stop flow coulometric titrns. is described, utilizing a gradient chamber, reagent generation chamber, and detector flow cell integrated into a single unit. The use of stop flow allowed for automated sample dilution up to a factor of 100 times. The system has been used to titrate samples of sodium hydroxide in the range 5 x 10^-4-4M, and nitric acid ranging from 5 x 10^-3-15M. Analyses over the entire range of concentrations yielded a relative standard deviation of less than 3%. A correlation coefficient of 0.999 was obtained for all comparisons with manual titrns. Remote spectrophotometric detection was performed with optical fibers. No frit or membrane is required to sep. the generating and counter electrodes within the system, yet the advantages of conventional coulometric titration, which eliminate the problems of reagent and calibration solution handling, storage or degrdn., are retained.
Sodium hydroxide Nitric acid Coulometry Spectrophotometry

"Bromine Number Determination By Coulometric Flow Injection Titration"
Talanta 1992 Volume 39, Issue 7 Pages 789-794
Richard H. Taylor, Camilla Winbo, Gary D. Christian* and Jaromir Rika*,

Abstract: The bromine number (unsaturation value) of petroleum distillates was determined by coulometric flow injection titrimetry with use of a single-line manifold system described previously (Ibid., 1992, 39, 285). The carrier stream (5.0 mL min-1) was acetic acid - methanol - aqueous 15% KBr (30:13:7) with addition of 1.8% methanolic HgCl2 as catalyst when needed. At a specified delay time flow was stopped and current was applied to generate Br as reagent in the cell chamber (0.90 ml). When the end-point had passed and sufficient unconsumed Br had formed for measurement, the current was cut off and flow was resumed to flush out the chamber. Unconsumed Br was detected by its absorbance at 470 nm. Results obtained for alkenes were nearer to theory value than those obtained by the ASTM Manual method. Sulfur compounds (e.g., ethanethiol) interfered but N-heterocyclic aromatics did not. In determination of 1-hexene (Br number theory 189.9, found 193), the coefficient of variation (n = 10) was 1.7%. The Br no., the number of g of Br which react with 100 g of a substance under given conditions, is a widely used parameter in the chemical and petroleum industries. A method of performing the Br number determination by coulometric flow injection titration, using both sequential injection with sinusoidal flow and single zone techniques, is described. Titrns. of olefins, known interfering compounds, and petroleum distillates were performed and compared with the results of conventional Br number titrns. Analyses yielded a relative standard deviation of 2%. Results compared favorably with those obtained by the conventional method for both pure (97%) olefins and petroleum distillates. The method is insensitive to interference from N compounds The CFIT technique combines the advantages of coulometric titrns.: controlled generation of reagent, avoidance of reagent standardization requirements and reagent storage and stability problems; with the advantages of FIA: small volume requirements which reduce cost and waste, controllable dilution through flow programming, toxic materials contained within a closed environment, and the capability of being automated.
Bromine Coulometry

"Flow Injection Titrimetric Analysis Of Vitamin C In Pharmaceutical Products"
Talanta 1993 Volume 40, Issue 5 Pages 593-598
Salah M. Sultan

Abstract: A method for determining ascorbic acid is described, based on its oxidation to dehydroascorbic acid with Ce(IV) in H2SO4 solution and monitoring the decrease in absorbance in a self-indicating system. Ascorbic acid solution was injected into a carrier stream (5 mL min-1) of 7.48 mM Ce(IV) in 0.1 M H2SO4 and the resulting solution was dispersed in a mixing chamber, propelled through a flow-through cell and detected spectrophotometrically at 410 nm. The method was applicable between 0.06 and 0.17 M ascorbic acid with a sampling frequency of 36 h-1 and coefficient of variation (n = 5) of 0.9. The system is simple, does not require an indicator, suffers no interferences and is sufficiently accurate for the determination of ascorbic acid in proprietary drugs.
Ascorbic acid Pharmaceutical Spectrophotometry

"Co-determination Of Sodium Metabisulfite And Starch In Corn Syrup By Flow Injection Coulometry"
Talanta 1994 Volume 41, Issue 1 Pages 31-38
Richard H. Taylor, Jon Rotermund, Gary D. Christian and Jaromir Ruzicka

Abstract: Sodium metabisulfite (I) in aqueous solution of corn syrup was determined by coulometric flow injection titration (CFIT; apparatus described) with iodine generated from 0.2 M KI and detection at 530 nm. A linear relationship was observed between CFIT and manual titration for 0.35 mM 0.029 M I (r2 = 0.996) which was independent of starch concentration. The rate of accumulation of the starch/iodine interaction product at a constant reagent generation rate after the I end-point was used to determine starch in the presence of I. A RSD of 1.4% was obtained for all starch analyzes (r 0.997) with a known relative concentration.
Metabisulfite Starch Corn Syrup Coulometry

"PVC Membrane Electrodes For Manual And Flow Injection Determination Of Tetraphenylborate: Applications To Separate And Sequential Titration Of Some Metal Ions"
Talanta 1994 Volume 41, Issue 4 Pages 523-530
Saad S. M. Hassan* and Ibrahim H. A. Badr,

Abstract: Electrodes for the determination of tetraphenylborate anion (TPB) were prepared by incorporating Fe(II)-bathophenanthroline-TPB, Ni(II)-bathophenanthroline-TPB or nitron-TPB complexes into PVC with dioctyl phthalate and 2-nitrophenyl phenyl ether as plasticizers. The membranes were glued to polythene tubes containing a Ag/AgCl reference electrode and an electrolyte of 0.01 M sodium tetraphenylborate/0.01 M NaCl. The response of the electrodes was measured in TPB test solution prepared in 0.05 M NaCl (pH 6-8) with a Ag/AgCl reference electrode. The calibration plots of the three electrodes were similar in terms of slope (-56.1 to -59.3 mV/decade), linear range (1 µM-10 mM), detection limit (0.92-3.6 µM) and response time (20-25 s). The electrodes were stable for 5 weeks. The electrodes were used for the direct potentiometric determination and the potentiometric titration of 1 µg/ml-0.6 mg/ml of TPB with average recoveries of 99.3%. The nitron-TPB electrode was incorporated into a cell to produce a flow injection detector for TPB with a detection limit of 1.6 µg/ml. The nitron-TPB electrode was also used to monitor the direct titration of cations with TPB.
Tetraphenylborate Cations Electrode Electrode Potentiometry

"Flow Injection Titration-linear Or Logarithmic"
Talanta 1994 Volume 41, Issue 6 Pages 949-955
R. Chen, J. Ruzicka* and G. D. Christian,

Abstract: The single-line FIA system of Taylor et al. (cf. Ibid., 1992, 39, 789) for flow injection coulometric titration was modified (described and illustrated). Organic solvent was loaded into the sample loop and injected into the mixing chamber by Karl Fischer reagent, the flow was stopped at an appropriate dilution and current was applied for a given period. The mixing chamber was flushed with the Karl Fischer reagent. A graph of titration time vs. water content in ethanol or methanol was linear up to 60 µL. For the determination of H2SO4 in oil refinery 'black acid' the mixing chamber was modified (details given) and flushed with 0.8155 M NaOH containing 0.04% bromothymol blue indicator before sample injection with 94.7 mM NaOH containing 0.04% indicator. NaOH was pumped at a constant rate for a given period and the absorbance was monitored until the indicator changed from yellow to blue. A calibration graph of absorbance vs. log. H2SO4 concentration was linear up to 1.98% wt. The coulometric method had good precision and linear calibration, whereas the continuous-flow method allowed rapid measurement with reasonable sensitivity; both techniques could be used for many applications.
Sulfuric acid Oil Coulometry Spectrophotometry Karl Fischer analysis

"Automated Viscometer Based On High-precision Flow Injection Analysis. 1. Apparatus For High-precision Flow, Injection Analysis"
Analyst 1983 Volume 108, Issue 1282 Pages 1-16
D. Betteridge, W. C. Cheng, E. L. Dagless, P. David, T. B. Goad, D. R. Deans, D. A. Newton and T. B. Pierce

Abstract: An automated viscometer was developed by modifying an Ostwald viscometer in which the sample (~50 µL) was injected into a carrier stream flowing along a narrow-bore tube. The time taken for the sample to travel a fixed distance was directly proportional to the viscosity. The measurement took ~30 s and gave a precision of 0.2 to 0.3% for viscosities ranging from 0.2 to 190 cP. The system could also be used for continuous monitoring of a carrier stream of unknown viscosity by injecting a sample of known viscosity. The use of refractometric, spectrophotometric, photometric, dielectric and conductometric detectors was evaluated and several microcomputer systems were investigated. The temperature had to be controlled to within 0.02°C
Conductometry Refractometry Spectrophotometry Viscosimetry

"Automated Viscometer Based On High-precision Flow Injection Analysis. 2. Measurement Of Viscosity And Diffusion Coefficients"
Analyst 1983 Volume 108, Issue 1282 Pages 17-32
D. Betteridge, W. C. Cheng, E. L. Dagless, P. David, T. B. Goad, D. R. Deans, D. A. Newton and T. B. Pierce

Abstract: The use of the apparatus described in Part I (Ibid, 108, 1983, 1) as a viscometer and for the measurement of diffusion coefficient has been evaluated. The effects of radius and length of the tube, sample volume and flow rate were studied. The viscosities of 15 solvents were measured. Diffusion coefficient for KMnO4 in water, ethanol and acetone were obtained.
Viscosimetry

"Determination Of Analytical Parameters In Drinking Water By Flow Injection Analysis. 2. Simultaneous Determination Of Calcium And Magnesium"
Analyst 1987 Volume 112, Issue 3 Pages 267-270
Francisco Ca&ntilde;ete, Angel R&iacute;os, Mar&iacute;a Dolores Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The flow system described incorporates two valves to select the indicator and EDTA reagent solution required for the determination of Ca and the sum of Ca and Mg. Calcium is determined by titration with 5 mM EDTA in 0.5 M NaOH, with murexide as indicator and monitoring at 510 nm. The flow rate is 0.8 mL min-1 and sample volume is 1.93 mL. The sum of Ca and Mg is determined by titration with 5 mM EDTA with Eriochrome black T as indicator in NH4Cl - NH3 buffer (pH 10.8). A flow rate of 0.9 mL min-1 and injection volume of 1.8 mL are used and detection is at 520 nm. Concentrations are obtained from calibration graphs prepared with calibration standards for Mg in the presence of various concentration of calcium. Calibration graphs were rectilinear for 2 to 25 and 25 to 400 µg mL-1 of Ca and for 2 to 280 µg mL-1 of the sum of Ca and Mg. (For Part I see earlier in this section).
Calcium Magnesium Hardness Water Spectrophotometry

"Analytical Information From Doublet Peaks In Flow Injection Analysis. 1. Basic Equation And Applications To Flow Injection Titrations"
Analyst 1987 Volume 112, Issue 4 Pages 523-526
Julian F. Tyson

Abstract: An equation previously described (cf. Anal. Chim. Acta, 1986, 179, 131) was extended to relate separation of the doublet peak, obtained when the reaction product of a flow injection titration is monitored, to all the basic operational variables. The equation was derived on the basis of the well stirred mixing chamber model. Variables consisted of flow rate, injection volume, volume of the mixing chamber, and reagent and sample concentration. The equation was tested by using a Cu(II) - EDTA reaction followed by UV detection. For OH-, the use of a gradient tube gave a rectilinear calibration range from 50 µM to 5M.
Copper(II) Spectrophotometry

"Flow Method For The Titration Of Weak Acids Or Weak Bases Using Linear Titration Plots"
Analyst 1987 Volume 112, Issue 7 Pages 1063-1066
Martinez Calatayud, P. Campins Falc&oacute; and R. Mic&oacute; Albert

Abstract: Continuous flow titrations of weak acids or weak bases can be carried out with a simple apparatus if the pH and titrant flow-rate data are treated using a linear titration plot method. Titrant is added to a flowing sample stream by a peristaltic pump with a precisely adjustable rotation rate. The results obtained for a variety of weak acids and weak bases are similar in accuracy to those given by corresponding burette titrations of discrete portions of sample.
Acids, weak Bases, weak Water Potentiometry

"Determination Of Ionic Surfactants By Flow Injection Pseudo Titration"
Analyst 1988 Volume 113, Issue 1 Pages 117-119
Chris J. Dowle, Brian G. Cooksey, (the late) John M. Ottaway and W. C. Campbell

Abstract: The construction is described of two flow-through surfactant-selective electrodes based on internally PVC-coated graphite tubes. The PVC coating contains 0.1% of tetrabutylammonium dodecyl sulfate for the cationic surfactant-selective electrode or 0.1% of hexadecyltrimethylammonium pentane-1-sulfonate for the anionic surfactant-selective electrode. The electrodes were incorporated in a flow injection system (described) for the titrimetric determination of surfactants (cf. Stewart and Rosenfield, Anal. Chem., 1982, 54, 2638). Optimum conditions were a flow rate of 0.9 mL min-1, a 70 µL injection volume and 1 µM-titrant (Na dodecyl sulfate or Hyamine 1622) as carrier stream. The lifetimes of the electrodes are of the order of 2 to 4 weeks. The precision of the method could be improved by elimination of manual peak-width measurement and spurious cell potential variations.
Surfactants, anionic Surfactants, cationic Electrode Electrode

"Automated Flow Injection Spectrophotometric Non-aqueous Pseudotitrations Of Amines And Their Hydrohalide Salts"
Analyst 1988 Volume 113, Issue 5 Pages 755-760
Constantinos A. Georgiou and Michael A. Koupparis

Abstract: A sample was dissolved in anhydrous acetic acid, and the solution was injected (200 µL) into a carrier stream, for amines, of 0.2 mM HClO4 - 12 µM malachite green (C. I. Basic Green 4) in anhydrous acetic acid. The carrier for the hydrohalide salts also contained 20 mM Hg(II) acetate. The absorbance of the solution was measured at 621 nm (e = 87,900) at a flow rate of 6.3 mL min-1. The rectilinear response ranges were generally 1 to 20 mM, with detection limits between 0.09 and 0.9 mM. The coefficient of variation ranged from 0.1 to 1.6% (n = 5). In the determination of theophylline and chlorpromazine hydrochloride in two commercial formulations, results agreed well with those obtained by an official method, with coefficient of variation (n = 3 for 3 samples) of 1.9 and 1.3%, respectively.
Amines Theophylline Chlorpromazine, hydrochloride Caffeine Thiamine Procarbazine hydrochloride Pharmaceutical Spectrophotometry

"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

"Iodimetric Determination Of Penicillins By A Triangle Programmed Flow-through Titration Technique"
Analyst 1988 Volume 113, Issue 6 Pages 881-884
Zsfia Feh&eacute;r, Ilona Kolbe and Ern&ouml; Pungor

Abstract: A flow-through triangle programmed titration technique for the determination of penicillin compounds has been developed. The hydrolysis of the penicillins and the titration procedure were performed under flow-through conditions. Electrolytically-generated iodine is used as the titrant and the detector system is a flow-through biamperometric type. Using the proposed method, the benzylpenicillin potassium content of a pharmaceutical preparation (Penicillin for Injection) has been determined.
Penicillins Electrode

"Application Of Flow-through Techniques To Drug Dissolution Studies"
Analyst 1991 Volume 116, Issue 5 Pages 483-487
Zs&oacute;fia Feh&eacute;r, Ilona Kolbe and Erno Pungor

Abstract: Two flow-through techniques, i.e., flow injection and triangle programmed flow titrimetry, have been used to follow the dissolution of durgs from pharmaceutical preparations. The applicability of direct ultraviolet spectrophotometry as a detection technique in flow injection was demonstrated for dissolution studies of nitrazepam- and metronidazole-containing pharmaceutical preparations. In the application of the triangle programmed titration technique, the dissolution of promethazine and ampicillin from pharmaceutical preparations was studied.
Drugs Sample preparation

"Self-indicating Flow Visible Spectrophotometric Titrations In A Variable-volume Tank Reactor"
Analyst 1991 Volume 116, Issue 6 Pages 631-640
Francis E. Powell and Arnold G. Fogg

Abstract: The rectilinear concentration. gradients produced in an emptying tank stirred reactor were used to titrate analytes within the tank, with spectrophotometric detection of the exit stream. Self-indicating titrations, in which changes in the absorbance of the analyte, titrant or product were monitored, agreed with theoretical predictions. Dispersion and transportation lag effects were observed, due to the external detection system. The precision was affected by the precision of the flow-rates used; relative errors were 1 to 2% with use of peristaltic pumps. The system was studied for titrations of iron(III) salicylate with EDTA, Fe(II) with MnO4-, Fe(III) with SCN- and 2,4-dinitrophenol with OH-. The system may be automated.
Spectrophotometry

"Determination Of Titratable Acidity Of Wines And Total Acidity Of Vinegars By Discontinuous Flow Analysis Using Photometric End-point Detection"
Analyst 1991 Volume 116, Issue 10 Pages 1051-1054
Terence J. Cardwell, Robert W. Cattrall, Graeme J. Cross, Gregory R. O'Connell, John D. Petty and Geoffrey R. Scollary

Abstract: The titratable acidity of white and red wines and the total acidity of vinegars were determined using the flow-based titration technique, discontinuous flow analysis with photometric end-point detection. A flow cell was used which had a low-volume mixing chamber fitted with a high-speed stirrer. Detection of the end-point was achieved using a light emitting diode and photodiode incorporated into the flow cell. A sample throughput of one every 4 s was possible with a precision of better than 1% relative standard deviation (n= 6) being observed for all standards and most samples. The results compared well with those from a standard manual titration.
Acidity Wine Food Spectrophotometry

"Determination Of Zinc And Acid In Zinc Plant Electrolyte By Discontinuous Flow Analysis"
Analyst 1992 Volume 117, Issue 12 Pages 1845-1848
Robert I. Mrzljak, Alan M. Bond, Terence J. Cardwell, Robert W. Cattrall, O. M. G. Newman and Geoffrey R. Scollary

Abstract: The method of discontinuous flow analysis was applied to the determination of zinc and sulfuric acid in zinc plant electrolyte by titration with EDTA and sodium tetraborate, respectively. Zinc was determined potentiometrically by using a polymer membrane-based zinc sensor and spectrophotometrically by using Alizarine Complexone as indicator, the acid was determined spectrophotometrically by using Bromocresol Green as indicator. It was necessary to carry out the titration of zinc at pH 4.3 to minimize any interference from Mn(II) and Mg(II) that were present in the samples. The results agreed well with those obtained by atomic absorption spectrometry and manual titrations. The use of sodium hydroxide as a titrant for the acid determination led to an error because of the precipitation of zinc hydroxide. This was partly correlated for by adding zinc and manganese to the acid standards and was overcome by using sodium tetraborate as titrant.
Zinc Sulfuric acid Zinc Potentiometry Electrode Spectrophotometry

"Pulse Coulometric Titration In Continuous-flow"
Analyst 1994 Volume 119, Issue 8 Pages 1835-1838
Anastas Dimitrov Dakashev and Veselina Todorova Dimitrova

Abstract: A suitable volume of a standard analyte solution or a solution of unknown analyte concentration was diluted to 25 mL with a reagent-generating solution containing 96.4 g of iron(III) ammonium sulfate, 112 mL of 96% H2SO4 and 87.5 mL of 85% H3PO4 per litre. The solution was passed continuously, at a constant flow rate, through a single-channel flow system consisting of consecutively joined generator and detector cells (diagram given). In the generator cell, the Fe(II) titrant was electrochemically generated in rectangular impulses of definite duration and different current magnitude. The analyte/titrant mixture then passed to the detector cell, and peaks were recorded corresponding to an excess of titrant generation, from which the concentration of the analyte was calculated (equation given). The described coulometric titration method was used to measure solution of K2Cr2O7, KMnO4, cerium(IV) sulfate and NH4VO3 from 0.1-10 milliequivalents/l, with RSD (n = 4-8) of 6.4-1.6%.
Metavandate Sulfate Dichromate Permanganate Coulometry

"Sequential Injection Analysis For Electrochemical Measurements And Process Analysis"
Analyst 1994 Volume 119, Issue 11 Pages 2309-2314
Gary D. Christian

Abstract: An overview is presented on sequential-injection analysis (SIA). The principles of SIA and some of its operational parameters are briefly described. Examples are provided to show that SIA is a versatile solution handling system for electrochemical and process systems. The examples given include coulometric titration with automated dilution, potentiometric studies using the matched potential method for assessing relative potentiometric selectivity coefficients, and the incorporation of the jet ring (fountain) cell in an SIA manifold for development of renewable reaction surfaces and sensors. (40 references).
Electrochemical analysis Coulometry Potentiometric stripping analysis

"Biamperometric Titration And Flow Injection Determination Of Cyclamate In Low-calorie Products"
Analyst 1995 Volume 120, Issue 9 Pages 2407-2412
Orlando Fatibello-Filho, Milton Duffles Capelato and Silvana Aparecida Calafatti

Abstract: Two methods for cyclamate (I) determination are described. In the titrimetric method, a portion (5 ml) of the sample in 1 M H3PO4 was titrated with 0.1 M NaNO2, with biamperometric detection at two Pt electrodes polarized at +0.7 V vs. Ag/AgCl. In the flow injection (FI) method, a portion (0.25 ml) of the sample in 1 M H3PO4 was injected into a carrier stream (2.96 ml/min) of 1 M H3PO4 containing 0.001% Triton X-100. The sample/carrier stream was merged with a reagent stream (0.77 ml/min) of 0.1 M NaNO2. The mixture was passed through a 50 cm coiled reactor before biamperometric detection of two Pt electrodes polarized at +0.7 V vs. Ag/AgCl. For the titrimetric method, the calibration graph was linear from 10 to 60 mM I, the detection limit was 1.3 mM and the RSD (n = 9) was 1%. Recoveries of I were 97.6-102.5%. For the FI method, the calibration graph was linear from 5 to 40 mM I, the detection limit was 2.5 mM and the RSD (n = 10) was 1.2%. Recoveries of I were 97.8-102.4%. The throughput was 90 samples/h. The methods were applied to various low-calorie products, viz., sweeteners, puddings, jellies and soft drinks.
Cyclamate Soft drink Food Food Artificial Biamperometry Electrode

"Silver(I)-selective Membrane Electrodes Based On Mono- To Quadridentate Podands"
Analyst 1998 Volume 123, Issue 2 Pages 383-386
Shim Sung Lee, Moon-Kyu Ahn and Sung Bae Park

Abstract: Nitrogen and sulfur containing podands were used as sensing components to prepare Ag(I) selective polymeric membrane electrodes. The electrochemical properties of these membrane electrodes were studied in a flow injection system and employed for the measurement of 2-thiobarbituric acid with titration.
Silver(I) 2-thiobarbituric acid Electrode Electrode

"Sequential Determination Of Titratable Acidity And Tartaric Acid In Wines By Flow Injection Spectrophotometry"
Analyst 1998 Volume 123, Issue 4 Pages 661-664
Antonio O. S. S. Rangel and Ildiko V. Toth

Abstract: A flow injection manifold is proposed for the sequential determination of titratable (total) acidity based on a pseudotitration and of tartaric acid based on the formation of a colored vanadate complex. The method involves inline dialysis prior to injection to avoid interference from the sample background absorption in the spectrophotometric detection. The changes in the color of both reactions were monitored using two flow cells aligned in the optical path of a single spectrophotometer. Wine samples were analyzed without any sample pre-treatment; table wines in the range 1-10 g L-1 (total acidity) and 0.5-4 g L-1 (tartaric acid) and port wines in the range 1-8 g L-1 (total acidity) and 0.5-5 g L-1 (tartaric acid). Sixteen samples can be measured per h, and the results were comparable to those obtained by reference procedures for both determinations RSDs (n = 10) generally lower than 3% were obtained.
Acidity, total Tartaric acid Wine Port Spectrophotometry

"Design And Evaluation Of A Potentiometric Detection System For Flow Injection Titrimetry"
Anal. Chem. 1982 Volume 54, Issue 1 Pages 43-46
S. F. Simpson and F. J. Holler

Abstract: A new potentiometric detection system for use In flow injection tltrimetry was designed and investigated. An antilogrithmic amplifier provided a signal related to proton concentration and enables manual selection of system sensitivity. A description of the mlcroelectrodes used as potentiometric sensors is provided. Precision within a set of titrations averaged 0.8% RSD and unknowns were determined with an average error of 4%.

"Exponential Dilution Chambers For Scale Expansion In Flow Injection Analysis"
Anal. Chem. 1982 Volume 54, Issue 13 Pages 2368-2372
Kent K. Stewart and A. Gregory Rosenfeld

Abstract: The use of a small mixing chamber in flow injection analysis systems is a unique and useful method to extend the range of detection for these systems. Colorimetric, fluorometric, conductometric, and flame emission detectors demonstrate the usefulness of this system. The scale expansion system is useful in those methods both requiring and not requiring a reagent to produce a detectable species. It is thought that this system will be useful in a number of flow injection applications.
Conductometry Fluorescence Spectrophotometry Spectrophotometry

"Continuous-flow Two-point Titration System For Chloride Using A Pair Of Silver - Sulfide Ion-selective Electrodes"
Anal. Chem. 1986 Volume 58, Issue 7 Pages 1502-1506
Hirokazu Hara, Yoshiki Wakizaka, and Satoshi Okazaki

Abstract: The two-point titration principle was used, with addition of a small excess of AgNO3 [in 0.1 to 0.2 M KNO3 and containing 250 to 500 mg L-1 of poly(vinyl alcohol)] being followed by the second addition in a flow stream. The Cl- concentration. could be continuously estimated from the p.d. between a pair of silver - sulfide electrodes. The accuracy was within 2% and the precision was within 0.9% for 6 to 14 mg L-1 of Cl- (n = 5). The maximum error in river water samples containing 9.6 to 16.9 mg L-1 of Cl- was 1.8% when compared with the results from a batchwise titrimetric determination.
Chloride River Electrode Electrode Potentiometry

"Sequential Determination Of Both Acids And Bases By Optosensing Flow Injection Analysis Using A Single-line Manifold"
Anal. Chem. 1987 Volume 59, Issue 23 Pages 2767-2773
Bruce A. Woods, Jaromir Ruzicka, and Gary D. Christian

Abstract: Dilute acids and bases were determined by single-point titration by injection of the sample (30 µL) into 0.1 M acetate buffer (pH 5.7) carrier stream followed by monitoring of the color change of an immobilized indicator (Colorphast, Merck) with use of an optical-fiber system (details given) in the same single-line manifold at the rate of 120 samples h-1. Plots of peak-height and peak-width measurements vs. concentration. gave rectilinear calibration graphs from 0.001 to 0.11M.
Acids Bases Spectrophotometry

"Automated Titrations Using A Discontinuous Programmed-flow Analyser"
Anal. Chem. 1989 Volume 61, Issue 18 Pages 2109-2116
Dennis P. Arnold, Russell M. Peachey, John D. Petty, and Denis R. Sweatman

Abstract: The technique of automated discontinuous programmed flow analysis is described and the operating principles and design of a working prototype instrument, employing syringe pumps driven by interchangeable cams, is discussed. Different cam profiles allow a number of direct reading or reagent addition methods, as well as both single- and dual-flow titrations. Results are presented for argentometric titrations of Cl-1 in water with anodized Ag micro-electrodes contained in two alternative mixer - sensor assemblies as detectors. Precision is generally better than 1% in the range 60 to 160 mg L-1 for analysis times of 30 s. Cycle times can range form 6 to 90 s with negligible sample carryover. Accuracy for waste water is ± 2 to 3%.
Chloride Environmental Waste Electrode

"Kinetic Determinations And Some Kinetic Aspects Of Analytical Chemistry"
Anal. Chem. 1990 Volume 62, Issue 12 Pages 441R-461R
Horacio A. Mottola, Dolores Perez-Bendito, and Harry B. Mark

Abstract: A review is presented, with 370 references, on kinetic methods based on, e.g., flow injection, thermometric titration, photometric monitoring, electrode reactions and luminescence.
Thermometry Spectrophotometry Electrochemical analysis Luminescence

"Automation Of Karl Fischer Water Titration By Flow Injection Sampling"
Anal. Chem. 1990 Volume 62, Issue 22 Pages 2504-2506
Yola Y. Liang

Abstract: Automating Karl Fischer (K-F) water titration was accomplished by recirculating the anode reagent from a coulometric K-F titrator through an air-actuated sampling valve. The automation was performed for online determination of water in liquid sample streams and for using an autosampler for unattended operation. The automated fixed-loop injection in a closed system improved precision and safety. Water levels as low as 28.3 µg were measured with a standard deviation of 0.46 µg. This versatile system is adaptable to many types of K-F titrators and various sample sizes, concentrations, and sampling rates. The sensitivity and accuracy of the method is only limited by the choice of titrator and reagents.
Karl Fischer analysis

"Development Of A Sequential Microtitration System"
Anal. Chem. 1996 Volume 68, Issue 8 Pages 1394-1400
Lloren&ccedil; Alerm and Jordi Bartrol&iacute;

Abstract: The design and construction of a sequential microtitration system are reported in the present work. The combination of the sequential injection analysis technique and a reaction chamber is the basis of this novel system. The reaction chamber features an integrated sensing assembly with miniature all-solid-state sensors. This setup is operated easily using titrant and sample solutions in the microliter range, much lower than the volumes employed in automatic titration systems. Furthermore, a separate reaction vessel for each sample is not required in the system reported here, The proposed setup titrates using sequential injections and does not need calibration procedures, as often happens with other pseudotitration systems adapted to now systems. The sequential microtitration system has been applied to a wide range of acid-base, complexometric, precipitation, and redox titrations. Accuracy and reproducibility of the method proposed are comparable to those obtained in batch titrations. The typical analysis time is around 5 min. The time employed in a cleaning operation or in a sample change procedure is under 2 min.
Magnesium Calcium Electrochemical analysis Sensor

"Titrimetry In A Continuous-flow System"
Fresenius J. Anal. Chem. 1978 Volume 293, Issue 5 Pages 413-415
H. F. R. Reijnders, J. J. van Staden and B. Griepink

Abstract: UFL
Sulfate Environmental Rain Surface Water Spectrophotometry

"Titrimetry In A Continuous-flow System. 3. Calcium Determination In Environmental Samples"
Fresenius J. Anal. Chem. 1979 Volume 295, Issue 5 Pages 409-410
H. F. R. Reijnders, J. J. van Staden and B. Griepink

Abstract: UFL
Calcium Environmental Spectrophotometry

"Titrimetry In A Continuous-flow System. 4. Determination Of Alkalinity Of Environmental Samples"
Fresenius J. Anal. Chem. 1979 Volume 298, Issue 2-3 Pages 155-156
H. F. R. Reijnders, J. J. van Staden and B. Griepink

Abstract: UFL
Alkalinity pH Environmental Environmental Spectrophotometry

"Exploitation Of Gradient Techniques In Flow Injection Analysis"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 656-659
Elo Harald Hansen

Abstract: A brief review is presented, with 16 references. Topics considered are gradient dilution and calibration, stopped-flow reaction rate measurements, titration, gradient scanning and simultaneous injection of two zones.

"A New Flow Injection Titration Analysis"
Fresenius J. Anal. Chem. 1988 Volume 330, Issue 6 Pages 484-488
Jun'ichi Toei

Abstract: The flow injection system consists of a multi-function pump, UV detector and sample syringe connected to a six-way injection valve with a loop containing a mixing chamber and attached reagent syringe. The sample and reagent can be stirred and the chamber volume can be varied between 15 and 150 µL. Results are reported of tests to determine reproducibility (coefficient of variation 2.0 to 2.5%) and the effects of carrier flow rate, reagent volume, carrier acidity, type of acid and sample concentration. on peak width and shape for the titration of NaOH (sample) with HCl, H2SO4 or acetic acid (carrier) with phenolphthalein as indicator (reagent). The sampling rate is 60 to 120 h-1 and the method is useful when the reagent is unstable, and for slow titration reactions.
Acids Bases Spectrophotometry

"Continuous Sample Monitoring By Flow-reversal Methodology"
Fresenius J. Anal. Chem. 1992 Volume 342, Issue 7 Pages 547-551
M. Romero-Salda&ntilde;a, A. R&iacute;os and M. Valc&aacute;rcel

Abstract: In the configuration proposed, the spectrophotometric detector was mounted in the loop of the injection valve. A single reversal of the flow direction, via a selecting valve, was activated when the detector signal fell to zero. Compared with the normal flow, peaks obtained by flow reversal were narrower and more Gaussian with lower dispersion. The influence of ionic strength, viscosity, surface tension and temperature on the dispersion were studied. Applications of the system, including acid - base titrations are described. A flow reversal methodology based on a single change of the flow direction was used for the continuous monitoring of samples injected into an unsegmented flow-system. The photometric detector was located in the loop of the injection valve and the flow was reversed once each whole plug emerged. Sample dispersion in the carrier stream was continuously monitored in systems with and without chemical reaction. The influence of various physicochem. variables was studied and some anal. possibilities are discussed.
Acids Bases 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

"Flow Injection Analysis Titrations Of Sulfide, Cysteine And Thiol-containing Drugs With Chemiluminescent Detection"
Fresenius J. Anal. Chem. 1993 Volume 345, Issue 11 Pages 723-726
I. L&oacute;pez Garc&iacute;a, P. Vi&ntilde;as and J. A. Mart&iacute;nez Gil

Abstract: The method is based on lowering of the chemiluminescence produced by the reaction between ClO- and luminol; the optimum pH for both the chemiluminescence reaction and its suppression by S2- or a thiol is 11.2 and the optimum ClO- concentration. in the flow injection analysis system used is 0.4 mM. Sample solution is injected into a stream of ClO- solution, which passes through a silicone tube (8 cm x 2 mm) and merges with 5 mM luminol before entering a flow-through chemiluminescence detector; the overall flow rate is 6.5 mL min-1. The method has been applied to aqueous solution of pharmaceuticals. Calibration graphs obtained by plotting the chemiluminescence peak width at half height vs. log. analyte concentration. were rectilinear for 1 to 100 mM of S2- and 0.1 to 100 mM of cysteine, N-acetylcysteine, N-penicillamine, 2-mercaptopropionylglycine (tiopronin) and 2-thiouracil; some variation in the slopes was observed. No interference was caused by fructose, lactose, glucose, sucrose, maltose, caffeine, salicylic acid, tartrate, oxalate or starch in up to 10-fold amount over N-penicillamine.
Sulfide Cysteine Thiols Pharmaceutical Chemiluminescence

"Flow Injection Analysis Using An Aquarium Air Pump"
Fresenius J. Anal. Chem. 1993 Volume 346, Issue 10-11 Pages 882-884
Kate Grudpan, Colin Taylor, Hans Sitter and Cornelius Keller

Abstract: Propelling systems for FIA that comprise an aquarium air pump in a pressure mode or a suction mode are described. Modifications to such a pump to facilitate rapid sample injection are illustrated. The determination of phosphate with (NH4)6Mo7O24 in the presence of ascorbic acid or ammonium with an FIA manifold in the suction mode and acid-base (HCl-NaOH) titrations in the pressure mode are outlined. The determination of Na, K and Ca by flow injection AES involving an aquarium air pump in the suction mode and a rapid injection valve is illustrated.
Sodium Potassium Calcium Phosphate Acidity Spectrophotometry

"Gran's Plot Titration And Flow Injection Titration Of Sulfate In Ground And Drinking Water With A Barium Ion-selective Electrode"
Fresenius J. Anal. Chem. 1994 Volume 350, Issue 10-11 Pages 630-632
O. Lutze, B. Ro&szlig; and K. Cammann

Abstract: The application of a barium ion-selective electrode for the determination of sulfate is reported. Titrations in the batch mode using the Gran's plot method [1] have been carried out. In the presence of a lithium acetate buffer and after the addition of isopropanol it has been possible to determine sulfate with a relative standard deviation (RSD) of 1.5%. The concentration range of the samples was 5-400 mg sulfate/l. Interfering ions were separated by cation-exchange. This indirect titration constituted the basis of a flow injection titration (FIA titration) system for the continuous determination of sulfate. By plotting the peakwidth vs. the logarithm of the sulfate concentration of the injected samples, linear calibration graphs in the range of 50-200 mg sulfate/l were obtained. In this system, the sample stream was pumped through an ion-exchange column, mixed with a buffer stream of lithium acetate and injected in a reagent stream of a BaCl2 solution. The resulting free Ba(II) concentration was monitored with a barium ion-selective electrode. The content of sulfate in ground and drinking water samples has been determined with a RSD between 1.2% and 1.3%.
Sulfate Water Ground Electrode

"Studies On Peak Width Measurement-based Flow Injection Analysis Acid - Base Determinations"
Microchim. Acta 1985 Volume 87, Issue 1-2 Pages 49-64
Jae-Seong Rhee and Purnendu K. Dasgupta

Abstract: Peak width measurement was used to determine strong acids or bases by injection into an aqueous indicator flow stream and spectrophotometric measurement in a flow-through cell (8 or 75 µL volume) at 615 nm (bandwidth 4 nm). The parameters investigated included concentration. and pK of the indicator, dimensions of the dispersion tube, signal level used for peak width measurement, sample volume, carrier flow rate, viscosity of the carrier stream and the diffusion coefficient of the analyte. As an example, the use of bromothymol blue is illustrated.
Acids Bases Spectrophotometry

"Sensitivity In Flow Injection Analysis"
Microchem. J. 1992 Volume 45, Issue 2 Pages 189-209
M. Valc&aacute;rcel and M. D. Luque de Castro

Abstract: A review is presented (with diagrams) which concentrates on the different ways of increasing or decreasing analytical sensitivity (96 references). An overview of the different ways of altering sensitivity in flow injection analysis (FIA) is presented. Both types of alterations, decreasing or increasing sensitivity, can be achieved by real or pseudodilution or (pre)concentration. steps. The great versatility of FIA is once more reflected in the large number of modes in which this anal. parameter can be altered. A review with 96 refs.

"Relationship Between Peak Width And Sample Concentration In Continuous-flow Injection Titration"
Anal. Lett. 1996 Volume 29, Issue 2 Pages 313-319
Wu, N.S.;Shi, W.J.;Su, H.W.

Abstract: A mathematical expression relating the measured time interval and the sample concentration in continuous-flow titrimetry was developed. All calculations were performed on an IBM-PC using BASIC programming.

"Determination Of Penicillin By Triangle Programmed Coulometric Acid-base Flow Titration In A System Incorporating An Enzyme Reactor"
Electroanalysis 1995 Volume 7, Issue 4 Pages 356-361
Zs&oacute;fia Feh&eacute;r, T. Len Nguyen, G&eacute;za Nagy

Abstract: A flow-through coulometric titration technique is described which can be applied for the determination of a wide variety of compounds. If necessary, the sample can be transformed in the measuring system into a form which can be titrated. Thus an enzyme-catalyzed reaction can also be used as a sample pretreatment step. In this article a measurement technique and apparatus are described in which an enzyme-catalyzed reaction is used for the fast and reliable determination of penicillin compounds. The principle of the technique is that an enzyme reactor is built into the sample line of the measurement system used for performing coulometric triangle programmed titrations. One of the components of the reaction mixture leaving the reactor (in this case penicilloic acid) is determined by coulometric acid-base titration. This technique is especially useful for the analysis of large sample series.
Benzylpenicillin Coulometry

"Chloride Determination In Serum By A Flow Injection Analysis Precipitation Pseudo-titration Technique Using A Flow-through All-solid-state Silver Electrode"
J. Pharm. Biomed. Anal. 1988 Volume 6, Issue 6-8 Pages 749-755
S. Alegret*, J. Alonso, J. Bartroli, J. Garcia-Raurich and E. Martinez-F&agrave;bregas

Abstract: Details are given of the flow injection system and of the design and construction of the tubular Ag electrode. A 50 µL portion of serum (diluted 1:10) was injected into the system, with 0.1 M KNO3 containing 0.5 mM AgNO3 as supporting electrolyte; a concentration. gradient was achieved by dispersion of the sample in a 0.55 mL mixing chamber, and peak width was measured. The system was applied in determination of Cl- over the range normally found in serum, viz, 96 to 104 mM. The coefficient of variation (n = 12) was 1.8%. Sixty samples could be analyzed in 1 h.
Chloride Blood Serum Electrode

"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

"Novel Flow Injection Analysis Systems For Drug Analysis"
J. Pharm. Biomed. Anal. 1992 Volume 10, Issue 10-12 Pages 769-773
Gary D. Christian

Abstract: Principles of operation and advantages of a cam-driven sinusoidal-flow syringe pump are described for use in conventional FIA or sequential injection analysis (SIA). SIA is a modified flow method that allows most analyzes to be performed on a single line with only one syringe. The apparatus is relatively cheap, readily automated and easily adaptable to different chemical methods. Flow injection coulometric titration is described as a valuable technique for analysis of unstable reagents or standards. Acid-base, redox, precipitation and complexometric titrants can be generated electrochemically, as can unstable titrants such as Cu(I), Br, Cl and Cr(II). The techniques described have potential for automatic drug assays. A review with 32 references. Flow injection analysis (FIA) has become a versatile tool for rapid and automated analysis. As its capabilities have increased, so have the complexity and operation of the apparatus. Ways to simplify both the apparatus and the application of injection techniques are investigated. A novel cam-driven syringe pump and the development of sequential injection analysis (SIA) are discussed, and some applications presented. Flow injection coulometric titrations. are presented as a means to further alleviate reagent stability and calibration problems. These systems have potential for automatically carrying out many drug assays.
Drugs Pharmaceutical Coulometry

"FIA Titrations Of Ephedrine In Pharmaceutical Formulations With A PVC Tetraphenylborate Tubular Electrode"
J. Pharm. Biomed. Anal. 1995 Volume 13, Issue 4-5 Pages 459-464
Manuel N. M. P. Al&ccedil;ada, Jos&eacute;L. F. C. Lima and M. Concei&ccedil;&atilde;o B. S. M. Montenegro*

Abstract: To prepare membranes for the tubular electrodes, 25 mL 0.1 M sodium tetraphenylborate were mixed with 20 mL 0.1 M tetrapentylammonium bromide in acetone, and the acetone was evaporated. The resulting crystals (0.06 g) were dissolved in 2.42 g 2-nitrophenyl-phenyl ether and portions (0.4 ml) of the resulting solution were mixed with 0.18 g PVC. Tubular electrodes were constructed as described previously (Lima et al., J. Flow Injection Anal., 1990, 7, 19) and applied to the flow injection analysis of ephedrine hydrochloride (I) in pharmaceuticals. Liquid samples equivalent to 2.5 mg I were diluted to 25 mL in phosphate buffer of pH 6.3. Powdered tablets equivalent to 12.6 mg I were dissolved in 25 mL phosphate buffer. Portions (80 µL) were injected into a carrier stream (6.8 ml/min) of 0.1 mM sodium tetraphenylborate in phosphate buffer. After passage through a mixing chamber (details given), potentiometric measurements were made vs. an Orion 90-02-00 double-junction reference electrode. The calibration graph was linear from 0.2-2 mM I and the RSD were 1.5%. Sample throughput was 60/h. The mean recovery of I in pharmaceuticals was 98.6% with a RSD of 2.5%. A flow injection system for the titration of ephedrine in pharmaceutical products with potentiometric detection was developed. For this purpose a tetraphenylborate tubular electrode was constructed. The electrode was prepared without inner reference solution and with a PVC membrane based on tetrapentylammonium tetraphenylborate as ion exchanger and 2-nitrophenylphenyl ether as mediator solvent. Its operational characteristics were evaluated in a low dispersion manifold and compared with more conventionally shaped electrodes using the same sensor. In the pH range 2.5-11.5, the electrodes showed linear response between 3.8 x 10^-6 and 0.1 M with a slope of -56.4 mV/log[BPh4]. Ephedrine determinations in pharmaceutical products were carried out in a single channel manifold with a mixing chamber incorporated and using the tubular electrode as detector. Recovery rates of 98.6±2.5% were obtained in the analysis of tablets, nasal drops and syrups with a sampling rate of about 60 h-1.
Drugs Ephedrine hydrochloride Pharmaceutical Pharmaceutical Pharmaceutical Electrode Potentiometry Electrode

"Future Applications Of ISFETs"
Sens. Actuat. B 1991 Volume 4, Issue 1 Pages 125-133
P. Bergveld

Abstract: The applications of ISFETs with respect to the measurement of ion fluxes are reviewed. The fast response of an ISFET has already been exploited in flow-through cells. To solve the reference electrode problem, a differential measurement set-up has been proposed in which the ISFET response is measured with respect to a REFET. Flow-through cells with two identical ISFETs and ISFETs with retarded responses are described. Flow injection titration systems, coulometric titrations and ion-step experiments with immunoFETs are considered. A review is presented, with 22 references. Future application areas to be exploited include flow-through systems and flow injection analysis, and biosenors.
Coulometry Field effect transistor Sensor

"Electrostatically Protected Ion-sensitive Field-effect Transistors"
Sens. Actuat. A 1984 Volume 5, Issue 2 Pages 127-136
Rosemary Smith, Robert J. Huber and Jiri Janata

Abstract: Two type of ISFETs with electrostatic protection have been designed and tested. They both utilize an electrically conductive layer incorporated into the gate of the ISFET. This layer is connected via an on-chip MOSFET switch to the outside circuitry. In the first type the conductor is capacitively coupled to the ion-selective membrane and to the solution. In this case the device output is proportional to the time differential of the concentration change. The applicability of this device to high-speed FIA titrations has been tested. In the second device the gate electrically contacts the membrane. In this case the output is identical to that of a conventional ISFET. The signal-to-noise ratio and the electrostatic protection of this ISFET are considerably improved.
pH Field effect transistor

"Flow Injection Titration Of Chloride In Electroplating Baths With A Silver Tubular Electrode As A Detector"
Anal. Sci. 1997 Volume 13, Issue 1 Pages 89-92
M. B. ETXEBARRIA, J. L. F. C. LIMA, M. C. B. S. M. MONTENEGRO and R. PEREZ-OLMOS

Abstract: A single-channel FIA manifold of high dispersion was used (schematic given). Sample was injected into a 1.5 mM AgNO3 carrier stream containing 1 M KNO3 to increase the conductivity and adjust the ionic strength through a 390 cm coil to create the exponential concentration gradient required in FIA 'pseudo-titrations'. The optimum flow rate was 3.6 ml/min. Ag tubular electrodes with a homogeneous crystalline membrane was used as the indicator electrode (cf. Ferreira and Lima, J. Flow Injection Anal., 1993, 10, 17). The method was suitable for chloride concentrations of 0.06-2.5M. The RSD was ~5% and the sampling rate was ~78 samples/h.
Chloride Industrial Electrode Potentiometry

"Flow Injection Titration Of Alkalinity In Natural Waters"
Anal. Proc. 1987 Volume 24, Issue 12 Pages 360-362
David R. Turner, Susan Knox, Michael Whitfield, Margarida Correia dos Santos

Abstract: A flow injection manifold for alkalinity measurements is described and illustrated; it consists of a mixing chamber, a capillary glass electrode detector and a reference electrode contacting the main flow stream via a free-diffusion liquid junction. A solution of 50 µM-HCl in 0.1 M NaCl is injected into a seawater carrier solution and potential readings are taken at a frequency of 5 Hz. The precision of the method is generally <1% and 30 samples h-1 can be analyzed.
Alkalinity Sea Electrode Electrode

"Principles Of Flow Injection Analysis"
Anal. Proc. 1987 Volume 24, Issue 12 Pages 362-364
Julian F. Tyson

Abstract: A review is presented, with 15 references, of the principles of flow injection titration.

"High Speed, On-stream Acid-base Titration Utilizing Flow Injection Analysis"
Adv. Instrum. 1984 Volume 39, Issue 1 Pages 279-285
NA (Karl D. Schick)

Abstract: Single point titration by flow injection analysis (FIA) allows rapid, on-stream determination of acids and bases. A small volume of acid or base is injected into a linear buffer, the resulting local pH change in the flowing buffer stream is linearly related to the concentration. of the injected acid or base. Process applications dealing with the determination of H2SO4 (1-10%), caustic (0.1-10%) and NH3 (1-6%) are discussed. A simple, on-stream sample clean-up procedure and device is also described. (SFS)
Ammonia pH Potentiometry Spectrophotometry

"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

"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

"Computer-assisted Automation Of Chemical Analysis Using Flow Injection. Application To A Fermentation Process"
Analusis 1991 Volume 19, Issue 8 Pages 266-270
Peris Tortajada M.; Maquieira A.; Lopez E.; Ors R.

Abstract: An automated modular flow injection system was developed for online monitoring of the following parameters in a fermentation process: pH, acidity (by titration), reducing sugars (by the method of Maquieira et al. (Anal. Chem., 1987, 112) and ethanol (by the method of Valcarcel et al., Anal. Chem., 1987, 59). The sampling rate was 30 h-1. The system was easily adapted to other types of analysis and was suitable for industrial process control.
Acidity Ethanol pH Sugars, reducing

"Estimation Of The Distance Change Between Cysteine-457 And The Nucleotide Binding Site When Sodium Pump Changes Conformation From E1 To E2 By Fluorescence Energy Transfer Measurements"
Biochemistry 1996 Volume 35, Issue 25 Pages 8419-8428
Shwu-Hwa Lin and Larry D. Faller

Abstract: The first indication of the size of a conformational change implicated in ion transport by sodium pump has been obtained by measuring the change in efficiency of fluorescence energy transfer between two specific locations on the α-subunit. The donor (5'- (iodoacetamido)fluorescein) attaches covalently to cysteine-457, and the acceptor (2'(or 3')-O-(trinitrophenyl)adenosine 5'-triphosphate) binds reversibly to the active site. The acceptor binds nearly 2 orders of magnitude tighter to the Na+ than to the K+ conformation of the enzyme and quenches donor fluorescence more efficiently in the Na+ than in the K+ conformation. The estimated distance between donor and acceptor, assuming random orientation of their emission and absorption dipoles, increases 2.9±0.6 A when the enzyme changes from the Na+ to the K+ conformation. Stopped-flow measurements of the change in fluorescence energy transfer efficiency with time when the doubly- labeled pump is mixed with Na+ or K+ demonstrate that the donor/acceptor pair reports the change between the E1 and E2 conformations of unphosphorylated enzyme. The observed first-order rate constant for the change in energy transfer efficiency depends sigmoidally on [K+] and inversely on [Na+], and both rate and amplitude data for the change in energy transfer efficiency can be fit with the same values of the rate and ion-dissociation constants as published data for the conformational change between E1 and E2 obtained by singly labeling the enzyme with fluorophores that report changes in protein microenvironment. The prerequisite for successfully measuring the distance change and equating the protein rearrangement with a step in the catalysis-transport cycle is that the donor by itself does not report the conformational change.
Protein, folding Fluorescence

"Development Of An Amperometric Flow Injection Immunoanalysis System For The Determination Of The Herbicide 2,4-dichlorophenoxyacetic Acid In Water"
Biosens. Bioelectron. 1997 Volume 12, Issue 6 Pages 499-510
Dieter Trau, Thomas Theuerl, Marianne Wilmer, Markus Meusel*, and Friedrich Spener

Abstract: An amperometric flow injection immunoanalysis (FIIA) system based on an immunoreactor with immobilized biocomponents on a silica surface has been developed for the determination of the herbicide 2,4- dichlorophenoxyacetic acid (2,4-D). In the antigen coating mode the hapten was immobilized and monoclonal primary antibody against 2,4-D together with alkaline phosphatase (AP)-labelled secondary antibody were used as sensing elements in a titration assay. In the antibody coating mode a biotinylated monoclonal antibody was immobilized on the surface of the immunoreactor and a 2,4-D-AP-conjugate was used for detection. For electrochemical measurements p-aminophenol enzymatically generated from p-aminophenyl phosphate was oxidized at a carbon working electrode at +150 mV versus Ag/AgCl. The system enabled the determination of 2,4-D in drinking water samples in the range from 0.2 to 70 µg/l. The whole system was computer controlled with a measuring time of 12 min for one determination.
2,4-dichlorophenoxyacetic acid Endothall sodium Water Immunoassay Amperometry Electrode Electrode

"Titration In Non-aqueous Solvents"
Bunseki 1992 Volume 1992, Issue 5 Pages 366-371
Izutsu, K.;Nakamura, T.

Abstract: A review is presented, with 70 references, on acid - base titrations, oxidation - reduction titrations, precipitation titrations and complexometric titrations in non-aqueous solvents and flow injection non-aqueous solvent titration.

"Liquid-flow Electroanalytical Techniques"
Bunseki 1981 Volume 1981, Issue 8 Pages 573-575
Kato, Y.

Abstract: A review with 17 references. A few examples from the recent literature are introduced, including flow-injection anal., the stop-flow method, and flow-through titration (SFS)
Electrochemical analysis

"Flow Injection Analysis Titrations Using A Volume-variable Mixer. 2. Flow Injection Titration Analysis For The Determination Of Brines Using An Ion Exchange Column"
Bunseki Kagaku 1986 Volume 35, Issue 9 Pages 832-835
Toei, J.;Baba, N.

Abstract: The brine is injected (20 µL) into a carrier stream (1 mL min-1) and passes through a column (1 cm x 8 mm) of TSKgel SAX (10 µm). The resulting alkaline plug is mixed with phenophthalein and detected at 575 nm; the peak width varies rectilinearly for 1 mM to 0.4 M NaCl. For 0.01 M and 0.04 M NaCl the coefficient of variation were 1.57% (n = 10) and 0.65% (n = 8), respectively. The method has been successfully applied to isotonic saline solution
Ionic strength Industrial Commercial product Ion exchange Spectrophotometry

"Continuous Determination Of Total Sulfur Oxide In Waste Gas By FIA"
Bunseki Kagaku 1990 Volume 39, Issue 2 Pages T29-T34
Korenaga, T.;Yokota, Y.;Okada, K.;Takahashi, T.;Moriwake, T.

Abstract: Sulfur oxides from exhaust gas were absorbed into 10% (v/v) H2O2 solution and the solution was subjected to flow injection analysis with 10% (v/v) H2O2 as carrier solution (0.3 mL min-1) and a Ba - sulfonazo III complex reagent solution (0.6 mL min-1). The reaction mixture was passed through a PTFE reaction coil (15 m x 10 mm) before spectrophotometric detection at 645 nm. The detection limit was 0.02 mg L-1 and the coefficient of variation was 0.5% for 5 mg L-1 of sulfur oxides. Results correlated well with those obtained by the official titration method (r = 0.996). The analysis time was 30 samples h-1.
Sulfur dioxide Waste Spectrophotometry

"The Metal-complexing Capacity Of Natural Waters Measured On The Basis Of Solvent Extraction And Reverse FIA"
Bunseki Kagaku 1995 Volume 44, Issue 12 Pages 989-999
Itabashi, H.

Abstract: Methods based on the backextraction, with the sample, of Cu(II) from its bis(benzoyltrifluoriacetonato)-complex in an organic solvent and on reverse FIA (manifold illustrated) are described. Results obtained by the two techniques were of the same order of magnitude. Methods for the measurement of copper(II) complexing capacity (CuCC) of natural waters by using a back-extraction of bis(benzoyltrifluoroacetonate) copper(II) (Cu(bfa)(2)) and the dithizone extraction rate of copper(II) complex were described. From the measurements of CuCC of river water samples, it was found that the CuCC of the water sample in the urban area was larger than that up-stream, due to a ligand originating from human activities. The conditional stability constant (beta) of the resulting copper(II) complex was determined by using the back-extraction method.beta values of river water samples were 10(9) similar to 10(10) order of magnitude. Free copper(II) concentration of the Kiryu river was estimated by using the side-reaction coefficient in the extraction of copper(II) with tenoyltrifluoroacetone. The free copper(II) concentration was estimated to be 10^-13 mol L-1 which is 10^-5 of total copper. Most of the copper(II) in the river, therefore, is complexed with naturally occurring ligands. A procedure for the measurement of metal complexing capacity by using reverse flow injection analysis (r-FIA) system was also described. The applicability of the method was evaluated by measuring zinc(II), cadmium(II) and lead(II) complexing capacities of both river and lake waters. The values obtained by the r-FIA system were in the same order of magnitude as those obtained by the back-extraction method, indicating the usefulness of the r-FIA method for the estimation of complexing capacity. (35 References)
Complexing capacity Sea River Spectrophotometry Sample preparation

"Trends In The Development And Application Of Flow Injection Analysis (FIA) In Pharmaceutical Analysis"
Cesk. Farm. 1992 Volume 41, Issue 2 Pages 62-68
Karlicek, R.;Solich, P.

Abstract: A review with 108 references discussing applications of flow injection analysis of pharmaceuticals in combination with chemiluminescence, fluorimetry, spectrophotometry, amperometry, and volumetry.
Pharmaceutical Chemiluminescence Fluorescence Spectrophotometry Amperometry

"Spectrophotometric Determination Of A Mixture Of Weak Acids Using Multivariate Calibration And Flow Injection Analysis Titration"
Chemom. Intell. Lab. Syst. 1993 Volume 19, Issue 2 Pages 243-254
Ronei J. Poppi and Celio Pasquini

Abstract: The sample was pumped continuously, and merged first with a mixture of acid - base indicators: to titrate HCl - acetic acid the mixture consisted of bromocresol green and phenolphthalein, whereas to titrate citric acid - tartaric acid or acetic acid - benzoic acid it consisted of methyl orange, bromocresol green, chlorophenol red, bromothymol blue and cresol red. The merged streams then merged with a stream of water into which 0.1 mL of 0.2 M NaOH was injected under computer control. The final stream was stirred magnetically to generate an alkaline gradient, and the mixture passed to a flow cell in which its spectrum (470 to 680 nm) was recorded repetitively by the rapid-scanning Hadamard-transform spectrophotometer described previously (Appl. Spectrosc., 1992, 46, 1822). Partial-least-squares modeling was used twice, viz, (i) to convert the absorption spectra into pH values in order to generate a time (t) x pH curve, and (ii) to process the t x pH curve on the basis of the response to standard acid mixtures. The applicable concentration. range for each acid was ~1 to ~5 mM. The mean relative error ranged from 2.8 to 6.5%.
Acids Spectrophotometry

"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).

"Determination Of Chloride In Soils By Flow Injection Potentiometric Pseudotitration"
Commun. Soil Sci. Plant Anal. 1996 Volume 27, Issue 5-8 Pages 1437-1445
Ferreira, A.M.R.;Rangel, A.O.S.S.;Lima, J.L.F.C.

Abstract: Air-dried, ground and sieved soil was shaken with water for 30 min, the mixture was filtered under reduced pressure, and the filtrate was stirred with activated charcoal and refiltered. The filtrate was injected into a carrier stream (3 ml/min) of 50 µM-AgNO3/ 1 mM HNO3/0.2 M KNO3 that then passed through an earthed tubular electrode and into a 300 µL mixing chamber with provision for stirring. Pseudotitrations were performed with use of a double-junction reference electrode, with 0.2 M KNO3 in the outer compartment, and a tubular Ag+-selective electrode with a homogenous crystalline membrane as an indicator electrode as described by Ferreira et al. (Food Chem., 1994, 50, 211). The calibration graph was linear for 5-500 ppm of chloride in dried soil with RSD (n = 10) of 0.42-4.8%. Sampling rates were 60-160 per h. A single-channel flow injection analysis (FIA) system for the pseudo-titration of chloride in soils was developed using a tubular silver ion selective electrode with a homogeneous crystalline membrane of Ag2S as potentiometric detector. This system allows the determination of chloride in soil extracts from 1 to 100 ppm. The results obtained for 15 soil extracts are in good agreement with those provided by the classical procedures with sampling rates varying from 60 to 160 determinations per hour with good precision (relative standard deviations lower than 4.8%).
Chloride Environmental Sample preparation Potentiometry Electrode Electrode

"FLUORIM - A Computer Program For The Automated Data Collection And Treatment Using Commercial Spectrofluorimeters"
Comp. Chem. 1991 Volume 15, Issue 4 Pages 307-312
L. A. Berrueta, L. A. Fernandez and F. Vicente

Abstract: A general purpose program that uses a PC microcomputer has been designed for the control of experiments in fluorimetry. This program allows the digital collection of the main types of scans that a commercial spectrofluorimeter can perform: emission, excitation and synchronic; as well as the measurement of the fluorescent intensity as a function of time. The program also allows a series of operations with previously stored spectra. These operations include screen and paper plots of the spectra, calculation of linear combinations of them and the nine first derivatives, as well as their relative maxima and minima.
HPLC Fluorescence Luminescence

"New Automatic Micro-titration Method"
Fenxi Huaxue 1994 Volume 22, Issue 5 Pages 482-484
Tan, A.M.;Ma, W.P.;Xu, Y.C.;Mao, A.Z.;Huang, J.L.;Xu, J.H.;Zhao, X.N.

Abstract: The design and construction of an automatic micro-titrator, based on the classical titration principle and FIA instruments, is presented. Advantages of this method are: simple, rapid, requiring only small amounts of reagent and sample as well as being more accurate and precise than FIA since its readout is linearly related to concentration of the analyte. The method was used in titration of NaOH with HCl, with RSD of 0.4%. As a practical example, it was also employed in analysis of NaOH/Na2O from a foundry; results agreed closely with those obtained by the chemical method.
Sodium hydroxide Sodium oxide

"Flow Injection Complexometric Titration Using Metal-ligand Buffers"
Fenxi Huaxue 1996 Volume 24, Issue 7 Pages 760-763
Chen, H.G.;Bao, L.J.;Pan, A.H.;Mo, J.Y.

Abstract: Portions (80 µL) of standard Cu solution were injected into a carrier stream of water at 1.5 ml/min and mixed with a metal-ligand buffer reagent stream (containing 0.1 mM Cu(II), 0.15 mM ethylenediamine tetrapropionic acid, 20 µM-4-(2-thiazolylazo)resorcinol and 0.1 M hexamine, adjusted to pH 6 with HCl) at 1.5 ml/min in a reaction coil (300 mm long) and detection of the colored complex formed at 540 nm. The calibration graph was linear, with a detection limit of 10 µM-Cu(II). The RSD (n = 11) was 0.92% for 40 µM-Cu. Only Th(IV), La(III) and Pb(II) interfered. Sampling frequency was 180 runs per h.
Copper Spectrophotometry

"Flow Injection Complexometric Titration Of Zinc With Zn-nitrilotriacetic Acid Metal-ligand Buffer Solution And 4-(2-thiazolazo)resorcin"
Fenxi Huaxue 1998 Volume 26, Issue 4 Pages 388-391
Bao, L.;Chen, H.;Tang, Z.;Mo, J.

Abstract: The conditions of flow injection complexometric titrating Zn with Zn-Nitrilotriacetic acid metal-ligand buffer solution and 4-(2-Thiazolazo)-resorcin were studied. The detection limit is 1.0 x 10^-6 mol/L and sampling frequency is 120/h. The interference and its elimination were also investigated. Zn in magnesium alloy was determined with satisfactory result.
Zinc Alloy Spectrophotometry

"Determination Of Zinc By Flow Injection Analysis Complexometric Back Titration"
Fenxi Shiyanshi 1991 Volume 10, Issue 2 Pages 37-38
Wang Guilan,Zhao Guoliang and Hu Yuze

Abstract: The cited determination (diagram of flow injection system given) was carried out with use of EDTA as complexing agent, Cu(II) as back titrant and spectrophotometric detection of the EDTA - Cu complex at 745 nm. The method was applied in the determination of Zn in zinc acetate and zinc borate.
Zinc Inorganic compound Inorganic compound Spectrophotometry

"Flow Injection Titration Of Chloride In Food Products With A Silver Tubular Electrode Based On An Homogeneous Crystalline Membrane"
Food Chem. 1994 Volume 50, Issue 4 Pages 423-428
Isabel M. P. L. V. O. Ferreira, Jos&eacute;L. F. C. Lima* and Ant&oacute;nio O. S. S. Rangel

Abstract: Wine, milk, beer and vinegar were tested for chloride by pseudo-titration using FIA and potentiometric detection. Sample was injected into a carrier stream composed of 20 µM-AgNO3/0.1 M KNO3 and directed to a well-stirred mixing chamber. The decrease in the Ag concentration was monitored by an Ag tubular electrode with a crystalline membrane of AgS prepared by mixing equal volumes of equimolar (0.1M) AgNO3 and Na2S solution, filtering and drying at 100°C for 24 h. After grinding, the membrane discs were prepared by pressing 0.25 g of sensor at high pressure to produce discs 10 mm in diameter and 0.4 mm thick. The membrane was set into a support (details given). The operating characteristics of the tubular electrode were compared with conventional electrodes and found to be similar. The optimum Ag concentration in the carrier stream was 0.1 mM and optimum carrier flow rate was 8.1 ml/min. Calibration graphs were linear from 10^-500 mg/l, 100-1800 mg/l and 40-500 mg/l for wine, milk and beer, and vinegar, respectively. Sampling rate varied from 120-136 samples/h. A comparison with reference procedures showed maximum RSD of 6, 0.3 and 1% for wine and milk, beer, and vinegar, respectively.
Chloride Wine Beer Milk Food Electrode Potentiometry

"Automated Titrations With An Alternate Flow: Linear Speed Variation System"
Instrum. Sci. Technol. 1995 Volume 23, Issue 2 Pages 91-102
Chaim N. Yarnitzky; Naphtali Klein; Orit Cohen

Abstract: The alternate-flow exponential speed-variation titrimeter described previously (Talanta, 1993, 40, 1937), which consists of two computer-controlled peristaltic pumps, two three-way valves, a mixing coil and a detector, can be operated in linear speed-variation mode. The rotation speed of the first (sample) pump decreases linearly with time while that of the second (reagent) pump increases likewise; the effects of deterioration of the tubing are eliminated by a reverse cycle effected by use of the valves. The system is suitable for rapid automated titrimetry; a complete titration takes <2 min. The accuracy depends on the mixing-coil delay and the time response of the detector, but at a fourfold sample-to-reagent concentration ratio the error is <0.5% and decreases as this ratio approaches unity. The performance of the system is demonstrated with acid-base and redox systems.

"Recent Advances In Flow Injection Analysis"
Int. Lab. 1985 Volume 15, Issue 8 Pages 14-23
Hansen, E.H.

Abstract: A review is presented, in which the development of flow injection analysis and the use of gradient dilution, gradient calibration, stopped-flow, gradient scanning, titrations, penetrating zones and other techniques with flow injection analysis are discussed. (18 references).

"Solid-phase Extraction Cleanup For Determining Ascorbic-acid And Dehydroascorbic Acid By Titration With 2,6-dichlorophenolindophenol"
J. AOAC Int. 1996 Volume 79, Issue 5 Pages 1236-1243
Krishna K. Verma, Archana Jain, Bhushan Sahasrabuddhey, Kalpana Gupta and Sanjeev Mishra

Abstract: Ascorbic acid is frequently determined by titration with 2,6-dichlorophenolindophenol. The determination is rapid, but the method is neither specific for ascorbic acid nor very sensitive. The coloring matter in the assay solution interferes with the visual endpoint, and iron(II), copper(I), sulfite, and sulfhydryl substances such as cysteine and glutathione interfere with the color reaction. Sample cleanup by solid-phase extraction with C-18 bonded silica was developed to remove the coloring matter. Extraction sorbent impregnated with 2,2'-bipyridyl, 2,9-dimethyl-1,10-phenanthroline (neocuproine) acid N-ethylmaleimide removes Fe(II), Cu(I), and sulfhydryl compounds, respectively. The procedure was applied to highly colored multivitamin pharmaceuticals, soft drinks, and fruit and vegetable juices. In contrast to the results from the original method, which is not applicable to such samples, the results obtained by the method incorporating cleanup were accurate and selective for ascorbic acid. The sample cleanup also permitted determination of dehydroascorbic acid by reducing it to ascorbic acid with cysteine and titrating the ascorbic acid formed with indophenol. As little as 3 µg ascorbic acid was determined by the method incorporating cleanup.
Ascorbic acid dehydroascorbic acid Soft drink Pharmaceutical Vegetable Fruit Sample preparation Spectrophotometry HPLC

"Automated Titrations: The Use Of Automated Multiple Flow Injection Analysis For The Titration Of Discrete Samples"
J. Autom. Methods Manag. Chem. 1981 Volume 3, Issue 1 Pages 30-32
KENT K. STEWART and A. GREGORY ROSENFELD

Abstract: In 1974 Fleet and Ho 1] successfully demonstrated an automated continuous flow titration system using a reagent gradient. This system had a throughput of only ten samples per hour, but it was significant since it demonstrated the principles for titration of discrete samples in continuously flowing streams. Nagy et al. [2,3 ]have also demonstrated a similar approach. In 1977, Ruzicka et al. [4] described the principles and an apparatus for the automated titration of manually injected samples using a gradient of the injected samples. A system is now described for automated titrations of discrete samples using a strategy [5] which automates the handling of discrete samples for flow injection analysis and Ruzicka's gradient titration system.

"Titration Of Spoilt Beer Samples By Flow Injection Analysis"
J. Autom. Methods Manag. Chem. 1982 Volume 4, Issue 4 Pages 176-182
J. G. WILLIAMS, M. HOLMES, and D. G. PORTER

Abstract: The titration of the acidity of beer by flow-injection analysis is described. Sodium hydroxide is used as titrant, and phenolphthalein is the indicator. After injecting the sample as a slug into the water carrier stream, the sample passes to a dispersion chamber, where the stream is continually titrated, and to a colorimeter, where transmittance at 550 nm is measured. Sampling rates of 65/h are typical.
Acids, volatile Acetic acid Beer Spectrophotometry

"Time-based Injection Approach For Monosegmented Continuous-flow Systems And Related Techniques"
J. Autom. Methods Manag. Chem. 1996 Volume 18, Issue 6 Pages 199-203
JO&Atilde;O CARLOS DE ANDRADE, RONEI JESUS POPPI, and ALINE REN&Eacute;E COSCIONE

Abstract: A time-based injection module which used three independently controlled solenoid valves (described) was evaluated for monosegmented continuous-flow analyzes (MCFA) and related techniques. Spectrophotometric FIA titrations of HCl with NaOH gave linear calibration graphs for 1-10 mM HCl. MCFA of Ca(II) by flame photometry gave calibration graphs which were linear for 10^-80 µg/ml Ca(II). Flow injection flame photometry of Ca(II) gave linear calibration graphs for 10^-100 µg/ml Ca(II). MCFA spectrophotometric analysis and flow injection photometric analysis gave linear calibration graphs for 0.2-2 µg/ml Cr(VI) with diphenylcarbazide as complexing agent. Experimental details are given.
Acids Chromium(VI) Spectrophotometry

"The Principles Of Flow Injection Analysis As Demonstrated By Three Lab Exercises"
J. Chem. Educ. 1979 Volume 56, Issue 10 Pages 677-680
Hansen, E. H.; Ruzicka, J.

Abstract: Three lab. experiments are described to illustrate a continuous-flow anal. technique, in which samples are injected into a continuously moving stream. The sample then mixes with and reacts with reagents in the stream (or added downstream) prior to its passage through a detecting device. Significant factors in this flow injection analysis technique are sample injection, reproducible timing, and controlled dispersion. The described experiments are for determination of chloride in water samples, determination of phosphate in output from a chromatography column, and titration of a strong acid with a strong base.
Acids Bases Chloride Phosphate Phosphates Water Spectrophotometry

"Flow Injection Analysis Titrations Using A Volume-variable Mixer"
J. Flow Injection Anal. 1986 Volume 3, Issue 1 Pages 27-36
Jun-ichi Toei Yoshinori Saigusa Nobuyuki Baba

Abstract: A New-type mixer(reactor) for flow injection titration analysis was developed and sodium hydroxide was determined using the mixer and flow injection titration technique. One of the chraracters of the mixer is that it has variable volume and another is that it has very low volume. A µstirrer is able to stir in it, however. To evaluate the character of the mixer a new-type analytical condition was proposed. Phenolphthaleine which is usually insoluble - in acidic or neutral pH, was solubilized in these conditions using non-ionic surfactant Triton X-100 and sodium hydroxide could be determined in a very simple system by only monitoring the change of absorbance at 575 nm. Reproducibility, linearity of calibration curves, effect of flow rate,volume of the mixer and composition of titration solution were discussed. Sodium hydroxide was able to be determined by neutral or alkaline solution without any trouble. Flow injection titration analysis could be performed with high precision using the mixer. Long linearity was gained by varing the volume of the mixer. As the mixer can be used for another purpose of FIA, applications will be discussed in future.

"Biamperometric Detection In Flow Injection Analysis"
J. Flow Injection Anal. 1994 Volume 11, Issue 1 Pages 34-44
Trojanowicz, M.A.;Michalowski, J.

Abstract: A review is presented of the applications of amperometric detection using two polarized electrodes and appropriate masking in FIA including direct, indirect, catalytic and single point titrimetric determinations. (31 references).
Biamperometry Turbidimetry

"Flow Injection Titration Using Reaction With Buffer Solution"
J. Flow Injection Anal. 1995 Volume 12, Issue 1 Pages 145-166
Toshihiko IMATO

Abstract: The methodology of flow injection titration of acids, bases, metals and redox compounds using a buffer solution with respect to pH, free metal ion concentration or redox potential has been proposed and applications of the proposed method to neutralization titration, chelate titration and redox titration are reviewed. The method is based on detection of variation in a property of the buffer solution due to a reaction with a sample injected in the buffer stream potentiometrically or spectrophotometrically. pH buffer solution and a glass electrode are utilized for determination of concentrated acids and bases, total amino acids in the Sake (Japanese rice wine). pH titration in non-aqueous solvent is applied to the determination of total alkalinity of lubrication oil and saponification values in food oil.

"Effect Of Ligand On Potentiometry And Its Application To Flow Injection Analysis"
J. Flow Injection Anal. 1998 Volume 15, Issue 2 Pages 198-208
Kawashima, T.;Teshima, N.;Katsumata, H.

Abstract: A review with 25 references. The redox potential of systems involving metal ions has been modified by the complexation with suitable ligands. This phenomenon can be potentially used for the development of novel redox systems for quantatitive analysis. Potentiometric titrations of metal ions in the presence of suitable ligands are presented. Development of spectrophotometric methods and complexing agents for metal ions is possible by using ligand effect in redox systems. Applications to estimation of complexing capacity in natural water and to catalytic method for copper(II) are demonstrated. Potentiometric flow titration methods are discussed.
Copper(II) Environmental Potentiometry

"Chloride Pseudotitration In Wines By FIA With A Silver Sulfide - Silver Tubular Electrode As Detector"
J. Food Comp. Anal. 1989 Volume 2, Issue 4 Pages 356-363
Jose L. F. C. Lima, and Ant&oacute;nio O. S. S. Rangel

Abstract: The tubular electrode was constructed (diagram given) and used in the analysis of wine which was introduced into the carrier stream (0.2 M KNO3 and 0.1 µM-AgNO3) in the FIA manifold. The concentration. profile, created in a well-stirred mixing chamber and generated by the decreasing Ag+ concentration. in the carrier stream was monitored by the variation of the potential between the tubular and reference electrodes. The calibration graph was rectilinear from 5 to 600 mg L-1 of Cl-. The within-run coefficient of variation was 1% (n = 10). Results compared well with those from a reference procedure (r = 0.990).
Chloride Wine Electrode Electrode

"Automated Flow Injection Pseudotitration Of Boric Acid"
J. Pharm. Sci. 1985 Volume 74, Issue 8 Pages 886-888
Paraskevi I. Anagnostopoulou, Michael A. Koupparis

Abstract: An automated flow injection pseudotitrimetric determination of boric acid, using a flow injection photometric analyzer controlled by a microcomputer, is described. The method is based on the injection of 200 µL of sample in a flowing stream of mannitol-bromothymol blue 'titrant' and measuring the peak width in time units. Equivalent times of 10^-70 s are measured with CV values of 0.1-0.4% (n = 5) and the analytical range is 1.5-309 mg/100 mL (2.5 x 10^-4 - 5 x 10^-2 M of boric acid. The method was evaluated by performing recovery studies in mixtures (mean 99.8%) and assays of commercial preparations which were compared with the official classical titrimetric method. Pharmaceutical preparations containing boric acid were dissolved in water and neutralized with 0.01 M NaOH or HCl. The solution were subjected to flow injection analysis by injection into the reagent stream (5 mL min-1) of 10 µM-phosphate buffer (pH 7) containing 0.1 mM bromothymol blue and 75 g L-1 of mannitol with absorbance measurement at 614 nm. The calibration graph was rectilinear for 0.25 to 50 mM boric acid; recovery was 99.8% and the coefficient of variation were 0.1 (0.06 and 0.31%) to 0.4% (16 ppm). The results agreed well with those obtained by the official titrimetric method.
Boric acid Pharmaceutical Spectrophotometry

"Multielement Isotope Dilution Analysis By Means Of Radiometric Titration"
J. Radioanal. Nucl. Chem. 1981 Volume 67, Issue 1 Pages 5-14
P. C. A. Ooms, G. P. Leendertse, H. A. Das, U. A. Th. Brinkman

Abstract: A theoretical concept is derived for multielement isotope dilution analysis in a liquid-liquid extraction system. The practical performance is based on radiometric titration. To that purpose a prototype of a titration/extraction vessel with flow injection has been constructed. For calculations of the initial concentrations of the elements of interest from the experimental data, a computer program has been developed.
Mass spectrometry Sample preparation

"Automated Determination Of Total Alkalinity In Surface, Ground And Domestic Waters By Single-point Titration And Flow Injection Analysis"
Lab. Pract. 1980 Volume 29, Issue 6 Pages 632-637
Basson, W.D.;Van Staden, J.F.

Abstract: NA
Alkalinity Ground Surface Water Electrochemical analysis Electrode Electrode

"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 Uranium In Process Solution By Flow Injection Analysis"
Lihua Jianyan, Huaxue Fence 1987 Volume 23, Issue 2 Pages 83-94
Xia, B.;Lang, H.

Abstract: Uranium was determined with use of a flow injection system incorporating a microcomputer. The method was based on the reaction of U with 4-(2-thiazolylazo)resorcinol with detection at 575 nm. Regression analysis was used to calculate U concentration. From 10 to 500 mg L-1 of U could be determined in the presence of masking agents. The coefficient of variation was 0.58% for 195.4 mg L-1 of U. The sampling rate was ~90 h-1. Results agreed well with those obtained by titrimetry.
Uranium Process liquor Spectrophotometry

"Flow Injection Analysis - Oxidation - Reduction Titration Of Iron"
Lihua Jianyan, Huaxue Fence 1991 Volume 27, Issue 6 Pages 361-362
Chen, J.;Ma, Q.

Abstract: A method for the determination of Fe was developed and applied in the analysis of ores. Sample was wetted with a little water, dissolved in concentrated HCl and heated with 4 M H2SO4. Following dilution with water, a portion of the solution was injected into a flow injection manifold into a stream of 0.5 M H2SO4 containing 0.008% sodium diphenylamine-4-sulfonate (1.3 mL min-1) which passed through a Jones' reduction column (12 cm x 3 mm) packed with zinc amalgam. The mixture was allowed to react with a stream of 0.16 mM K2Cr2O7 containing H2SO4 and H3PO4 (1.3 mL min-1) as titrant and the absorbance of the resulting mixture was monitored at 550 nm. The calibration graph was rectilinear for 7.3 to 60.8 mM Fe, the average recovery was 105% and the coefficient of variation was 0.43%. Sample throughput was 10 to 12 h-1.
Iron Geological Spectrophotometry

"Study On Flow Injection Potentiometric Titration - Precipitation Titration Of Lithium With Fluoride"
Lihua Jianyan, Huaxue Fence 1998 Volume 34, Issue 2 Pages 58-61
Dan Dezhong,Wu Jinghui

Abstract: A simple and effective gradient mixing tube was designed, and a new potentiometric titration method for the determination of Li by using F- ion selective electrode was established. The EtOH-H2O (9:1) solution containing 1 x 10^-5-1 x 10^-4 M F- was used as carrier, and F- and Li+ formed LiF ppt. quant., causing the change of the content of F-. The optimum anal. conditions were decided. The linear ranges were 5 x 10^-5-1 x 10^-2 M (titrant concentration. CF: 1 x 10^-5M) and 3 x 10^-3-1 x 10^-1M. The relative standard deviation was 2.67-3.19%. The interferences of Ca2+ and Mg2+ were eliminated by adding CyDTA and Na2CO3. The method was used for the determination of Li in natural bittern with satisfactory results.
Lithium Food Potentiometry Electrode

"Determination Of The Aluminum Complexing Capacity Of Fulvic Acids And Natural Waters, With Examples From 5 New-zealand Rivers"
Mar. Fresh. Res. 1996 Volume 47, Issue 1 Pages 11-17
DJ Hawke, KJ Powell and JE Gregor

Abstract: An FIA technique with 7 s reaction time was used to analyze free plus labile Al in fulvic acid (FA) solutions and natural waters at pH 4.7, without the need for separation procedures. Titrations of these solutions using incremental pH or total Al were used to determine pH binding curves or estimates of the 'kinetic' Al complexation capacity (Al-CCk) respectively. The operational definition of Al-CCk relates to the capacity of a humic substance or natural water to bind Al through a 7-s FIA reaction time under defined experimental conditions of chromophore (GAS) concentration, ionic strength, and pH. Both Al binding strength and complexation capacity were greater than the corresponding Cu-CC (ISE) values. The Al-CCk measurements at pH 4.7 were 710 µmol Al g-1 v. 590 µmol Cu g-1. Al-CCk results (pH 4.7) were higher for soil FA (710 µmol g-1) than for aquatic FA (390 µmol g-1). AI-CC, results (pH 4.7)for five unfiltered river waters from different catchments gave results in the range 6.5-9.8 µmol Al L-1. The differences between total (natural) Al in the samples and Al-CCk were between 2.7 µM and 8.6 µM. Filtration experiments identified fractionation patterns between total (natural) Al and the fraction of Al-CCk not utilized. The Al titration of alginate, another component of natural organic matter, is reported.
Aluminum Alginate River Environmental Voltammetry

"Successive Potentiometric Titration Of Copper(II) And Zinc(II) By Use Of A Copper(II) Ion-selective Electrode"
Nippon Kagaku Kaishi 1980 Volume 1980, Issue 12 Pages 1490-1493
Saruhashi, M.;Ohzeki, K.;Kambara, T.

Abstract: A mixture of copper(II) and zinc(II) is titrated with 3, 6-dioxaoctane-1, 8-diamine-N, N, N', N'-tetraacetic acid (customarily abbreviated to EGTA or Y) at first in acetate buffer solution of pH around 4. After the first end point is indicated by copper(II) ion-selective electrode, an appropriate amount of ammonia buffer solution is added, the solution pH being adjusted to 9, and then the titration is continued unitl the second end point is recorded. The first end point is due to the formation of binuclear copper(II) complex with EGTA, Cu2Y, and one can determine the half amount of copper(II). The second end point indicates the total amount of copper(II)and zinc(II), and thus one can determine both ions successively.Effects of nicke(II), cobalt(II), manganese(II), cadmium(II), aluminum(III), iron(III), and tin(IV) were studied by adding one of them separately to a mixture of 50 µmol of copper(II) and zinc(II). Copper(II) is successfully determined in the presence of equimolar amount of each ion except tin(IV), while in the ammonia buffer solution cadmium(II), cobalt(II), nicke(II), and manganese(II) are totally or partly titrated with EGTA and interfere with the determination of zinc(II). Iron(III) and aluminum(III) do not interfere with the titration of total amount of copper(II) and zinc(II) in the ammonia buffer solution. The interference of -tin(IV) (5 µmol) in the acetate buffer solution is effectively removed by fluoride ions, while in the ammonia buffer solution tin(IV) hydroxide is formed.
Copper(II) Zinc(II) Immunoassay Electrode Potentiometry

"Flow Injection Methods: A New Tool For Instrumental Analysis"
Phil. Trans. R. Soc. A 1982 Volume 305, Issue 1491 Pages 645-656
J. Ruzicka and D. Betteridge

Abstract: Gradient flow-injection techniques are reviewed and their use for serial assays and research in instrumental methods of analysis is outlined. The increasing importance of flow injection analysis as a new solution-handling technique in a laboratory is demonstrated with several examples.

"Application Of The Flow Injection Analysis Method For Single-point Titration Of Acids"
Pr. Nauk. Inst. Chem. Nieorg. Metal Pierwiastkow R 1988 Volume 58, Issue 1 Pages 254-258
Matuszewski, W.

Abstract: Flow-injection single-point titration of acids is based on biamperometric measurement of iodine formed quant. in the reaction of iodide with iodate. Results are presented for determination of sulfuric, hydrofluoric, monochloroacetic, formic, and acetic acids. The slopes of the calibration plots, which are linear for about 1-10 mM acid, depend on the strength of the acid, decreasing from sulfuric acid to acetic acid. With microcomputer online data processing relative standard deviations were about 0.2%. (SFS)
Acids Sulfuric acid Hydrofluoric acid Chloroacetic acid Formic acid Acetic acid Amperometry

"Implementation Of Flow Injection Titration Technique Based On The CAMILE Data Acquisition And Control System"
Process Control Qual. 1992 Volume 2, Issue 3 Pages 215-224
W.A. Heeschen, D.C. Greminger and E.D. Yalvac

Abstract: For the determination of strong and weak acids, a product stream is sampled by a pneumatically actuated six-port valve, and a portion (80.4 µL) is injected into a titrant stream of aqueous 0.01 M NaOH. The solution passes to a 1 mL mixing cell fitted with an ISI pH electrode connected to a Cole-Parmer pH transmitter. The equipment is connected and controlled by a CAMILE 3000 and Compaq DeskPro 386 computer running version 11 of the CAMILE software, by means of which the Savitzky-Golay algorithm is implemented for data smoothing and differentiation to detection the inflection points. The logic flow diagram of the system is presented. Calibration is effected with stable and standards modelling those in the product stream. In the titration of binary mixtures of strong and weak acids (or, with an acidic titrant stream, strong and weak bases), the pKa values should differ by at least 5 units; the strong species is titrated first.
Acids, weak Acids, strong Electrode Potentiometry

"Status Of Process Flow Injection Analysis And Current Trends"
Process Control Qual. 1994 Volume 6, Issue 2-3 Pages 91-95
E.D. Yalvac and R.A. Bredeweg

Abstract: The status of process FIA is presented and the maintenance issue is discussed. Miniaturization is reviewed, with an example application illustrating the determination of total alkalinity by flow-injection titration technique. (14 references).
Alkalinity, total

"Flow Injection Analysis - How It All Started"
Quim. Anal. 1993 Volume 12, Issue 1 Pages 3-6
Hansen, E.H.

Abstract: The early experiments and concepts which led to the development of the FIA approach are described. The injection of the sample into an unsegmented carrier stream, controlled dispersion and reproducible timing characterized the system. The development of the FIA titration procedure is outlined. (15 references).

"Acid Base Flow Titration Based On The Use Of An Automatic Burette"
Quim. Anal. 1994 Volume 13, Issue 1 Pages 31-35
Bartroli, J.;Alerm, L.;Garcia Raurich, J.;Masip, J.

Abstract: Continuous-flow titrations were conducted using a combination of FIA and an automatic burette. The optimization process for the flow system allowed the evaluation of the influence of flow rate and reaction coil length in the observed equivalence volume. The results obtained using two detection systems, a flat-membrane glass electrode and a pH-sensitive ISFET sensor, are compared. Acetic acid was used as a carrier solution and NaOH as the titrant. The injection of small volumes of the titrant in the carrier channel gave a titration graph. From this curve, an equivalence volume could be derived. A calibration surface could be produced by plotting the equivalence volume for each concentration of the acid carrier and the basic titrant. By using the surface polynomial equation acid-base titrations could be performed over a wide working range. Use of the ISFET sensor improved analytical speed and resolution.
Acids Bases, weak Field effect transistor Electrode Electrode

"Potentiometric Determination Of Chloride Ion In Milk And Dairy Products By FIA Titration"
Quim. Anal. 1995 Volume 14, Issue 2 Pages 121-124
Alegret, S.;Alonso, J.;Bartroli, J.;Garcia Raurich, J.;Martinez Fabregas, E.;Sanchez Rodriguez, J.

Abstract: A 100 µL portion of milk was injected into a carrier stream (1 ml/min) of 0.1 M KNO3 and passed into a 0.55 mL variable-volume dilution chamber. The stream then passed through a ground electrode to a flow-through reference electrode as previously described (Alegret et al., Ibid. 1987, 6, 278) and a tabular flow-through Ag25 heterogeneous membrane all-solid-state electrode for the detection of the end point of the titration. The calibration graph was linear for 0.4-0.8 M chloride. Results are discussed.
Chloride Dairy Products Cows Milk Potentiometry Electrode

"Titration Device By Flow Injection"
Rev. Chim. 1989 Volume 40, Issue 6 Pages 532-535
Danet, A.F.;Gurguta, A.

Abstract: A new titration device by flow injection for acid-base titrns. is described and schematically shown. It consists of a peristaltic pump, an injection valve, a mixture chamber and a cell for spectrophotometric flow determinations The detection limits for samples of 16.8 and 46.6 µL were 3.5 10^-3 and 1.4 10^-3 M HCl, respectively, at a reagent flow of 2 mL/min of 10^-3 M KOH. The device allows 60-80 titrns./h. (SFS)
Acids Hydrochloric acid Spectrophotometry

"Flow Injection Analysis. 1. Principles And Working Methods"
Rev. Chim. 1990 Volume 41, Issue 5-6 Pages 490-495
Danet, A.F.;Luca, C.

Abstract: A review is presented, with 44 references, covering a brief history of the cited method, its principles and mathematical analysis. The various techniques and apparatus used are described, with examples of their use, including continuous- or interrupted-flow, titrations, solvent extraction and gas diffusion methods.
Sample preparation

"Method And Device For Rapid Titration By Direct Flow Injection"
Rev. Chim. 1992 Volume 43, Issue 7 Pages 398-401
Danet, A.F.

Abstract: A modification is described of the device presented by Danet and Gurguta (Ibid., 1989, 40, 532), in which the mixing chamber is designed as part of a flow-line tube (2 mm vs. 1 mm diameter). The device was applied in alkalimetric titrations (1 to 10 mM KOH, 1 to 100 mM HCl; indication of the end-point with bromothymol blue and detection at 620 nm).
pH Spectrophotometry

"Flow Injection Analysis Of The Total Alkalinity In Surface, Ground And Domestic Water Using A Single-point Titration System"
Water SA 1986 Volume 12, Issue 2 Pages 93-98
van Staden JF

Abstract: An electrometric single-point titration system for the determination of total alkalinity in surface, ground and domestic water is described. The method is based on a combination of flow injection analysis and single-point titration. The sample is reacted with an acid linear-response buffer solution and the pH of the resulting solution is measured with a glass electrode in a flowthrough assembly. The method is suitable for the analysis of total alkalinity at a rate of up to 120 samples per hour with a coefficient of variation of better than 0,8%. Color and turbidity interferences are eliminated.
Alkalinity, total Ground Surface Water Electrode

"Ion-selective Electrodes Based On Neutral Carriers As Sensors For Organic Cations. Membrane Octylammonium-selective Electrodes Based On Phosphoryl-containing Podands"
J. Anal. Chem. 1993 Volume 48, Issue 12 Pages 1974-1982
Shvedene, N.V.;Pletnev, I.V.;Nemilova, M.Y.;Sinenko, O.D.;Sheina, N.M.;Baulin, V.E.

Abstract: The electrode membrane was prepared as described by Moody (et al., Analyst (London), 1970, 95, 910) from PVC plasticized with o-nitrophenyl octyl ether and containing oxybis(ethyleneoxymethylene)bis(diphenylphosphine oxide), which was the best of the acyclic polyether podands examined. The membrane was deposited on a Pt wire and dried for 18 h, and was conditioned in 0.1 M octylammonium chloride for ~3 days. A Ag/AgCl electrode containing 0.1 M LiCl was used as reference electrode. The electrode was suitable for titrations by static or flow injection methods.
Cations, organic Electrode Electrode Electrode Sensor

"FIA Acid–base Titrations With A New Flow-through PH Detector"
Anal. Bioanal. Chem. 2005 Volume 382, Issue 8 Pages 1981-1986
H. Kahlert, J. R. P&ouml;rksen, J. Behnert and F. Scholz

Abstract: A pH-sensitive detector for flow-through potentiometry based on a graphite/quinhydrone composite electrode was applied for flow-injection analysis (FIA) titrations. Hydrochloric acid and acetic acid were titrated by injection of samples into a sodium hydroxide carrier solution. System conditions were optimized by variation of flow rate, injection volume and titrant concentration. The parameters sampling frequency, residence time and dispersion coefficient were determined. The evaluation of peak width (time between the two inflection points on each side of the peak), peak area and slope of the raising edge of the peak lead were studied with respect to their use for calibration. Hydrochloric acid and acetic acid could be titrated down to a concentration of 2 x 10^-4 mol L-1 using 150 µL injection volumes, which is almost ten times lower than can be achieved using color indicators and a spectrophotometric detection.
Acids Bases pH Electrode

"A Monosegmented Flow Titration For The Spectrophotometric Determination Of Total Acidity In Vinegar"
Anal. Sci. 1999 Volume 15, Issue 7 Pages 665-668
Ricardo S. Honorato, M&aacute;rio C. U. Ara&uacute;jo, Germano Veras, Elias A. G. Zagatto, Rui A. S. Lapa And Jos&eacute; L. F. C. Lima

Abstract: A monosegmented flow system involving sample and titrant sequential injections and the establishment of a tandem plug between two air bubbles is proposed for automated titrations. The end point is found after successive variations of the sample and titrant volumes, determined by an algorithm based on the one-dimensional optimization method of Fibonacci. The set up includes a multi-port solenoid valve with four inlets and one outlet. The feasibility of the system was demonstrated in the spectrophotometric determination of the total acidity in vinegar with NaOH and phenolphthalein used as the titrant and indicator, respectively. The sample throughput was ~30 h-1 and consumption of the sample and titrant was about 0.7 mL. The results were in agreement with the expected values, with relative errors lower than ±0.4%. After 12 successive analyzes of typical samples with a 47.1 - 53.4 total acidity, expressed as g L-1 acetic acid, the relative standard deviations of the results were estimated within the 1.2 - 2.1% range.
Acidity, total Food Spectrophotometry