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
Website: @unf

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Classification: Beverage -> alcoholic -> wine

Citations 149

"Metals Determination In Wines By Sequential Injection Analysis With Flame Atomic Absorption Spectrometry"
Am. J. Enol. Vitic. 2000 Volume 51, Issue 2 Pages 131-136
Rui Cerdeira C. Costa, M. Isabel Cardoso, and Alberto N. Araújo

Abstract: This paper describes the application of sequential injection analysis with flame atomic absorption spectrophotometric detection (SIA/FAAS) for the determination of Zn, Mn, Fe, and Cu in Portuguese Verde, Maduro, and Porto wines. The basic configuration of the system allowed the determination of Zn, Mn, Fe, and Cu, the latter in concentrations higher than 0.20 mg/L. Selecting a sample volume of 340 µL allowed the determination of Zn and Mn up to 1.50 and 3.00 mg/L, respectively. The Fe determination was accomplished using 85, 120, and 340 µL sample volumes for Fe contents in the range of 1.50 to 15.00 mg/L, 0.50 - 10.00 mg/L, and 0.25 - 5.00 mg/L, respectively. Wine samples with Cu contents in the 0.20 to 2.00 mg/L range were analyzed with a sample volume of 750 µL. The determination of Cu trace levels was carried out using an heterogeneous-phase pre-concentration unit composed of a commercial cartridge packed with silica C18 coupled to the system. Cu was retained as diethylammonium-N,N-diethyldithiocarbamate chelate. Using about 2 mL of sample allowed determination of Cu between 0.05 and 0.50 mg/L. A comparison of the results obtained by the proposed methodologies and the reference procedures presented relative deviations less than 5%. Repeatability of determinations was always better than 3% (RSD).
Zinc Manganese Iron Copper Spectrophotometry Sequential injection C18 Method comparison

"Analytical Pervaporation: An Advantageous Alternative To Headspace And Purge-and-trap Techniques"
Chromatographia 2000 Volume 52, Issue 5-6 Pages 265-272
M. D. Luque de Castro and L. Gámiz-Gracia

Abstract: An overview of the principles and general applications of analytical pervaporation is presented. The different designs of both the analytical pervaporation module and the continuous manifolds to which the pervaporator is connected are discussed. The versatility of this non-chromatographic continuous separation technique for circumventing some of the shortcomings encountered in the automation of the overall analytical process is shown. Examples of methods developed for samples (both liquid and solid) in the environmental, food and beverage, and clinical and pharmaceutical fields are shown. The potential of pervaporation as an alternative to static and dynamic well-established approaches such as headspace and purge-and-trap sampling prior to gas-chromatographic separation is demonstrated. Examples of this approach involving both solid and liquid samples are discussed.
Spectrophotometry Review Pervaporation

"Biosensing For Determination Of Food Components And Estimation Of Their Functions"
Nippon Shokuhin Kagaku Kogaku Kaishi 2001 Volume 48, Issue 2 Pages 157-163
Kiyoshi MATSUMOTO, Hiroyuki UKEDA

Abstract: A review on methodologies of food analysis by combination of using immobilized biocatalysts and flow injection analysis. Rapid evaluation of food functional properties, e.g., super oxide dismutase (SOD)-like activity and inhibition of a-glucohydrolase (AGH) and angiotensin I-converting enzyme (ACE) activities is also discussed. 22 references.
l-Malate Lactate Enzyme, activity Immobilized enzyme Reactor

"Enzymatic Determination Of Ethanol And Glycerol By Flow Injection Parallel Multi-site Detection"
Anal. Chim. Acta 2000 Volume 416, Issue 2 Pages 205-210
António O. S. S. Rangel and Ildikó V. Tóth

Abstract: A flow injection method was developed for the sequential enzymatic determination of ethanol and glycerol in wines, using immobilized ethanol dehydrogenase and glycerol dehydrogenase, respectively. The enzymes were immobilized separately on alkylaminated controlled pore glass. A multi-site spectrophotometric detection system was used in parallel configuration to monitor the absorbance change in the two independent analytical channels. A 50-fold dilution of the samples was necessary before injection. The working range was between 0.05 and 0.5% (v/v) for the ethanol and between 0.03 and 0.3 g L-1 for the glycerol determination, with corresponding detection limits of 2 x 10^-3% (v/v) and 2 x 10^-3 g L-1. Relative standard deviations (RSD) (n=9) lower than 2.3% for the ethanol and 2.1% for the glycerol determination were found. For 13 samples of different types of table and Port wines, the results showed good agreement with the corresponding reference procedures; a two level recovery study also showed good accuracy for the developed methods. The sampling rate was 10 hr-1, corresponding to 20 determinations per hour.
Ethanol Glycerol Spectrophotometry Reactor Method comparison Immobilized enzyme Controlled pore glass Multidetection

"Determination Of Sulfur Dioxide By Flow Injection Analysis With Amperometric Detection"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 445-451
M. Granados, S. Maspoch and M. Blanco

Abstract: The SO2 is determined by direct injection or after separation in a diffusion cell with a PTFE membrane. The detection cell is of wall-jet type with vitreous-carbon working and auxiliary electrodes and silver - AgCl reference electrode. With the diffusion cell at 25°C the response shows two rectilinear ranges between 0.06 and 6 mg L-1 and 12 and 110 mg l-1, and at 50°C the range is from 0.04 to 5 mg l-1. The coefficient of variation at 3 mg L-1 are 1.7 and 2.3% (n = 7) with detection limits of 0.03 and 0.02 mg L-1 at 25°C and 50°C, respectively. Sulfide and NO2- interfere at mg L-1 levels. The method is applied to the determination of free SO2 in wine.
Sulfur dioxide Amperometry Electrode Electrode Interferences Gas diffusion Teflon membrane

"Individual And Simultaneous Enzymic Determination Of Ethanol And Acetaldehyde In Wines By Flow Injection Analysis"
Anal. Chim. Acta 1986 Volume 185, Issue 1 Pages 57-64
F. Lázaro, M. D. Luque de Castro and M. Valcárcel

Abstract: For determination of acetaldehyde(I), a solution of the sample and a solution of aldehyde dehydrogenase (NAD+) and NAD+ in phosphate buffer solution (pH 9.0) were each injected into separate streams of the buffer solution (0.62 mL min-1), which were then mixed in a 140-cm reactor column; the NADH formed was determined spectrophotometrically at 340 nm. Ethanol(II) was determined similarly with use of alcohol dehydrogenase as enzyme and addition of glycine and semicarbazide hydrochloride to the buffer solution Calibration graphs were rectilinear for final solution of 20 to 160 nl mL-1 of II and 1.0 to 8.0 µg mL-1 of I; mean dilutions of 80 for I and 1500 for II were required. In the determination of 5 µg mL-1 of I and 80 nl mL-1 of II the coefficient of variation were 0.5 and 0.7%, respectively (n = 11). A procedure for the simultaneous determination of I and II involving dual reagent injections and diode-array detection was devised.
Acetaldehyde Ethanol Spectrophotometry Enzyme Simultaneous analysis

"Indirect Atomic Absorption Spectrometric Determination Of Mixtures Of Chloride And Iodide By Precipitation In An Unsegmented Flow System"
Anal. Chim. Acta 1987 Volume 193, Issue 1 Pages 127-135
P. Martínez-Jimenez, M. Gallego and M. Valcárcel

Abstract: Chloride and iodide are injected into a carrier silver nitrate and the precipitates formed are retained on a stainless-steel filter, so that total chloride and iodide can be determined by the decrease in the atomic absorption signal for silver. The silver chloride precipitate is subsequently dissolved with ammonia and chloride only is determined. Iodide is determined by difference. Mixtures of these anions at µg mL-1 levels can be determined for chloride/iodide ratios from 7.5:1 to 1:60, with a sampling frequency of ~10 h-1. Applications to the determination of chloride in foodstuffs and wines are described. Up to 10 samples per hour can be handled and 50-100 samples can be run before the filter must be cleaned.
Chloride Iodide Spectrophotometry Indirect Precipitation

"Versatile Automatic Stopped-flow System For Routine Analysis"
Anal. Chim. Acta 1987 Volume 199, Issue 1 Pages 29-40
A. Loriguillo, M. Silva and D. Pérez-Bendito

Abstract: A versatile, automatic stopped-flow system featuring a mixing module and real-time data collection and treatment is presented. The mixing module is compatible with a number of spectrophotometers and spectrofluorimeters. The fast reaction between iron(III) and thiocyanate is used to evaluate the performance of the system and to develop a routine procedure for the determination of iron in wines, with a reaction time of 3 s. The calibration is linear over the range 1-30 µg mL-1, with a RSD of 0.9% (n = 11) for 10 µg Fe mL-1 and a high sample throughput (120 h-1) is achieved.
Iron Fluorescence Spectrophotometry Automation Stopped-flow

"Determination Of Glucose In Alcoholic Beverages By Flow Injection With Two Internally Coupled Injection Valves And An Enzyme Reactor,"
Anal. Chim. Acta 1988 Volume 211, Issue 1-2 Pages 281-285
J. Ruz, A. Ríos, M. D. Luque De Castro and M. Valcárcel

Abstract: Two flow configurations are described for the determination of a component in samples for which the matrix provides varying blank values. The enzyme reactor was either in the injection system (manifold A) or between the injection system and the detector (manifold B). The determination is described of glucose in wines and beers, with an enzymatic reactor packed with immobilized hexokinase and glucose-6-phosphate dehydrogenase. The NADPH produced was monitored spectrophotometrically. Manifold A was used to determine glucose at 5 to 60 µg mL-1; the coefficient of variation for 40.0 µg mL-1 of glucose was 2.0%. The range of application was increased to 10 to 100 µg mL-1 by use of manifold B and a first-derivative signal.
Glucose Spectrophotometry Immobilized enzyme Injection technique

"Integrated Retention - Spectrophotometric Detection In Flow Injection Analysis. Determination Of Iron In Water And Wine"
Anal. Chim. Acta 1989 Volume 219, Issue 2 Pages 231-238
F. Lazaro, M. D. Luque de castro and M. Valcárcel

Abstract: A sample (2 ml) containing 10 to 200 ng mL-1 of Fe(III) at pH 2 is inserted into the carrier stream, comprising 0.2 M NaF - 0.5 M NaOH - 0.02 M Na acetate - 2 mM Na2EDTA, at 2.0 mL min-1. After mixing in a coil, the stream is mixed with 0.4 M NH4SCN - 0.5 M HCl reagent solution at 2.0 mL min-1, and the Fe(III) - SCN- complex formed is retained on Dowex 1-X2-200 anion exchanger located in the flow cell. When the sample plug reaches the resin, the pH change causes an increased absorbance at 480 nm. Subsequently, the absorbance increases because of retention of the complex. The method is selective, with a determination limit of 10 ng mL-1 and a rectilinear range of 10 to 400 ng mL-1. Peak height, absorbance increment and tangent curve measurements each have advantages. Preconcentration of the analyte is rapid and the blank signal from colored samples is avoided. The method was applied in the determination of Fe in water and wine, with an average recovery of 100.3 and 98.8%, respectively.
Iron Spectrophotometry Preconcentration Dowex Solid phase detection Resin

"Determination Of Glucose In Wine And Fruit Juice Based On A Fibre-optic Glucose Biosensor And Flow Injection Analysis"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 293-301
Bernd A. A. Dremel, Bernhard P. H. Schaffar and Rolf D. Schmid

Abstract: A glucose biosensor based on an oxygen optrode with immobilized glucose oxidase was used in a flow injection system to determine glucose in wine and fruit juice. The consumption of 0 was determined by dynamic quenching of the fluorescence of decacyclene by molecular 0. Glucose oxidase was adsorbed on a sheet of carbon black and cross-linked with glutaraldehyde. Carbon black was used as an optical isolation to protect the optrode from interference from ambient light and sample fluorescence. The calibration graph was rectilinear for 0.1 to 500 mM glucose, with a coefficient of variation of 2% for 100 mM (n = 5). The optrode was stable for >400 h in continuous use. No interference at 500 mg L-1 of SO32- for 5 mM glucose was observed. Up to 60 samples h-1 could be analyzed with a precision similar that of standard methods. The method was simple, economical, could be computer-controlled and required minimal sample prep.
Glucose Sensor Fluorescence Optrode Computer Quenching Interferences Computer Standard method Method comparison

"Simultaneous Determination Of Carbon Dioxide And Sulfur Dioxide In Wine By Gas Diffusion - Flow Injection Analysis"
Anal. Chim. Acta 1989 Volume 225, Issue 2 Pages 443-448
P. Linares, M. D. Luque de Castro and M. Valcárcel

Abstract: The analytes were separated from the sample matrix by passage through the PTFE membrane of a gas diffusion cell, trapped by the acceptor stream (H20) and transported to a potentiometric cell containing a glass-calomel electrode for determination of total CO2 plus SO2. The stream was then merged with a p-rosaniline - formaldehyde solution in 0.7 M H2SO4, and a colored compound was produced by SO2 only, which was determined at 578 nm; CO2 was determined by difference. Mixtures of CO2 and SO2 could be analyzed with an average error of 3.9 and 5.9%, respectively. The reproducibility was 7% and the sampling frequency was ~25 h-1. The method was applied to the simultaneous determination of CO2 and SO2 in wine and was as effective as the standard EEC method, but 8 to 10 times faster, used less sample and reagent and was completely free from interference.
Carbon dioxide Sulfur dioxide Potentiometry Electrode Spectrophotometry Gas diffusion Interferences Teflon membrane Dual detection Simultaneous analysis

"Gas Diffusion Dilution Flow Injection Method For The Determination Of Ethanol In Beverages Without Sample Pretreatment"
Anal. Chim. Acta 1990 Volume 234, Issue 1 Pages 213-220
Wolfgang Künnecke and Rolf D. Schmid

Abstract: Sample was injected into water as carrier stream and passed to a gas diffusion unit, in which ethanol passed through a membrane into a stream of 0.1 M phosphate buffer (pH 7.5). This solution was passed through a column containing immobilized alcohol oxidase, and the H2O2 produced was detected at a platinum working electrode at 700 mV vs. Ag - AgCl. The limit of detection was 6 ppm or 0.1 mM ethanol (coefficient of variation 5.2%, n = 15 to 20), and up to 60% ethanol could be determined, depending on the membranes used. The coefficient of variation was generally 0.2 to 0.7%. Up to 180 samples h-1 could be analyzed. The operational half-life of the immobilized enzyme was 8000 injections in 44 h. The method was applied to beer, wine, spirits and pharmaceuticals.
Ethanol Electrode Gas diffusion Membrane Immobilized enzyme

"Determination Of Glucose In Fermentation Processes By Means Of An On Line Coupled Flow Injection System Using Enzyme Sensors Based On Chemically Modified Electrodes"
Anal. Chim. Acta 1990 Volume 235, Issue 2 Pages 265-271
Roger Appelqvist and Elo H. Hansen

Abstract: An easy-to-make disposable biosensor (prep. described) based on a graphite electrode [chemically modified with an ethyl ether solution of bis(benzophenoxazinyl) derivative of terephthaloic acid] with an adsorbed, cross-linked layer of glucose dehydrogenase was applied in the online monitoring of glucose in a wine fermentation process. The contents of a fermentation unit were continuously pumped (1 l min-1) to a spiral filter unit and back to the fermenter. The resulting filtrate was transported to an online dialyser equipped with a hydrophilic polypropylene membrane and the dialysed fraction was injected in to a carrier stream (0.75 mL min-1) of 0.1 M phosphate buffer (pH 6.5) - 0.15 M NaCl containing 2 mM NAD and analyzed by flow injection analysis with detection by a three-electrode detector. The detection limit was 50 µM-glucose and the electrode response was rectilinear up to 40 mM. The system permitted up to 60 determinations h-1 and the electrode was stable for at least 3 days of continuous use.
Glucose Electrode Electrode Sensor Enzyme Membrane

"Flow Injection System For The Fluorimetric Determination Of Fructose With An Immobilized Mannitol Dehydrogenase Reactor"
Anal. Chim. Acta 1991 Volume 243, Issue 2 Pages 183-186
Nobutoshi Kiba, Yukari Inoue and Motohisa Furusawa

Abstract: Sample solution was injected into a carrier stream of water (0.5 mL min-1), which was merged with 10, 100 or 200 µM-NADH in 0.2 M phosphate buffer (pH 7.0; 0.5 mL min-1) for reaction in a reaction column (5 cm x 4 mm) of mannitol dehydrogenase immobilized on poly(vinyl alcohol) beads (prep. described) at 40°C. The decrease in NADH was monitored fluorimetrically at 465 nm (excitation at 340 nm). Calibration graphs were rectilinear for 3 to 30, 15 to 150 or 60 to 600 µM-fructose (I) for 10, 50 and 200 µM-NADH, respectively; the detection limit was 1 µM-I for 10 µM-NADH. Seventeen carbohydrates did not interfere; D-mannitol did interfere. The sampling rate was 30 h-1. The column retained >80% of its activity after continuous use over 2 months. The method was applied in the determination of I in fruit juice, wine and cola.
Fructose Fluorescence Buffer Column Heated reaction Immobilized enzyme Interferences

"Enzymatic Determination Of Free L-(levo)-malic Acid In Must And Wine By Stopped-flow Flow Injection Analysis"
Anal. Chim. Acta 1991 Volume 247, Issue 1 Pages 61-66
C. Garcia De María, T. Manzano Muñoz and A. Alonso Mateos, L. García De María

Abstract: Flow injection/stopped-flow procedures are described for the determination of free L-(-)-malic acid based on the catalytic activity of malate dehydrogenase. Malic acid concentrations higher than 7.5 times 10^-7 M can be determined with a sampling frequency of 80 h-1. The proposed procedures were applied to the determination of the L-(-)-malic acid content in samples of different types of wine and must undergoing malolactic fermentation.
l-Malic acid Spectrophotometry Stopped-flow Catalysis

"Determination Of Sulfite In Wine Through Flow Injection Analysis Based On The Suppression Of Luminol Chemiluminescence"
Anal. Chim. Acta 1992 Volume 266, Issue 2 Pages 317-323
Yu Liang Huang*, Jong Min Kim and R. D. Schmid

Abstract: Several flow injection manifolds were tested (diagrams given) for the detection of sulfite in samples in the presence of 1 mM EDTA by the supression effect of sulfite on the reaction between 50 µM-H2O2, 0.5 mM luminol and 4 iu mL-1 of horse-radish peroxidase. The calibration graph was rectilinear from 0.05 to 0.8 mM sulfite (or from 10 to 200 µM-sulfite with 20 µM-H2O2); the coefficient of variation (n = 5) for wine was 4%. A sensitive and rapid assay for total sulfite and SO2 was based on the suppression of luminol chemiluminescence. EDTA greatly amplified this suppression. Flow-through anal. was applied to evaluate the anal. potential for measuring sulfite concentration, with 50 µM H2O2, 0.5 mM luminol, 1 mM EDTA and 4 U/mL horseradish peroxidase being used to induce chemiluminescence. The signal of the suppression of light emission could be obtained within 1 min and was linearly proportional to sulfite concentration. from 10 to 800 µM with a relative standard deviation of <2% over the measurable range. Flow injection analysis with a gas diffusion system based on this principle was applied to measure sulfite concentrations. (free and total) in wine. The results (free and total sulfite concentrations.) can be obtained within 10 min for each wine. The assay was fairly specific for sulfite.
Sulfite Chemiluminescence Indirect Quenching Gas diffusion Interferences

"Flow Injection Determination Of Ethanol By Fibre-optic Chemiluminescence Measurement"
Anal. Chim. Acta 1992 Volume 266, Issue 2 Pages 325-329
Xiangfang Xie, Ahmad A. Suleiman and George G. Guilbault*, Zhiming Yang and Zhu-an Sun

Abstract: The H2O2 generated from the oxidation of ethanol in the alcohol oxidase reactor described by Swindlehurst and Nieman (Ibid., 1988, 205, 195) was measured by the luminol reaction with K3Fe(CN)6 as catalyst. The luminescence was transmitted from the flow cell via optical fibers to the detector. The calibration graph was rectilinear from 3 to 750 µM ethanol with a detection limit of 3 µM; the coefficient of variation (n = 20) was 2.4% for 300 µM ethanol. Analysis time was 1.5 min. The results on seven wines compared well with those reported by the manufacturer and those from the AOAC method. The H2O2 generated in the enzymatically catalyzed oxidation of EtOH was measured by the luminol chemiluminescence reaction with K hexacyanoferrate(III) as a catalyst. Alcohol oxidase immobilized on aminopropyl glass beads packed in a glass column was used for EtOH oxidation and H2O2 formation. The chemiluminescence measurement was made by using an optical fiber to transport the luminescence from the flow cell to the detector in conjunction with a flow system. This assay system responded linearly to EtOH concentrations of 3 x 10^-6 to 7.5 x 10^-4 M with a precision of 2.4% and an analysis time of 1.5 min.
Ethanol Chemiluminescence Indirect Optical fiber Standard method Glass beads Catalysis

"Enhanced Automatic Flow Injection Determination Of The Total Polyphenol Index Of Wines Using Folin - Ciocalteu Reagent"
Anal. Chim. Acta 1992 Volume 269, Issue 1 Pages 21-28
Mercedes Celeste, Consuelo Tom&aacute;s, Andreu Cladera, Jos&eacute; Manuel Estela and Victor Cerd&agrave;*

Abstract: Wines, after appropriate dilution in water, were analyzed for total polyphenol content in a flow injection system with water as the carrier (0.7 mL min-1). The carrier was mixed with Folin - Ciocalteu reagent, diluted 1:10 with water and mixed with 0.5 M NaOH in a reaction coil (1 m); spectrophotometric detection was at 760 nm. Rectilinear calibrations were obtained over the range 12.5 to 150 mg L-1 of tannic acid and 5 to 100 mg L-1 of gallic acid. The method was tolerant to the presence of 400 mg L-1 of SO2, 50 mg L-1 of ascorbic acid and 40 g L-1 of glucose. Different types of wines were analyzed at 60 h-1.
Polyphenol index Tannins Tannic acid Gallic acid Spectrophotometry Interferences

"Automated Determination Of Reducing Sugars By Atomic Absorption Spectrometry"
Anal. Chim. Acta 1993 Volume 276, Issue 2 Pages 385-391
M. C. Yebra, M. Gallego and M. Valc&aacute;rcel*

Abstract: Wine samples (0.25 to 1 ml) were diluted with water to 25 ml, the pH was adjusted to 4.6 to 8.2 with dilute KOH, and the sample was pumped into a reversed flow injection system. A portion (200 µL) of pre-mixed Fehling A and B solution was injected into the carrier stream and the sample - reagent plug was halted in a precipitation coil at 95°C for 10 min. The change in the Cu AAS signal with respect to a blank was then monitored after diluting the carrier stream with water. Reducing sugars could be determined in the range 10 to 110 µg mL-1 with a coefficient of variation (n = 11) of 2.7%; the recovery was close to 100%. Results are compared with those obtained by conventional methods.
Sugars, reducing Spectrophotometry Method comparison Indirect Reverse

"Determination Of Total And Free Sulfur Dioxide In Wine With A Continuous-flow Micro-distillation System"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 401-407
A. Maquieira*, F. Casamayor and R. Puchades, S. Sagrado

Abstract: For free SO2, flowing sample was merged with a pre-mixed stream of H2O/1.2 M H3PO4 (1:1) in the described and illustrated apparatus and a portion was transferred to a distillation unit comprising a coiled column in a glycerol bath at 100°C. The liberated SO2 was swept by N2 to an absorption module, entrained in a stream of 2,2'-dinitro-5,5'-dithiodibenzoic acid (0.32 g/l) in phosphate buffer solution of pH 6 and the resulting solution passed via a reaction coil to a detector operated at 410 nm. The procedure for total SO2 was similar but the sample was first merged with 4 M NaOH and then with 1.2 M H3PO4 before reaching the injection valve. Calibration was effected with standard sodium sulfite solution (0-30 or 0-200 µg/ml for free or total SO2, respectively); response over these ranges was linear. The optimization of the experimental parameters is described. Acetaldehyde interfered but ascorbic acid did not. The detection limit was 5 or 1 µg/ml for total or free SO2, respectively, and the RSD in the middle of the calibration range was 2.9 or 10.4%, respectively (n = 10). Results for red and white wines agreed with obtained by standard distillation and iodimetric methods.
Sulfur dioxide Interferences Optimization

"Spectrophotometric Flow-through Sensor For The Determination Of Sulfur Dioxide"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 408-413
P. Richter, M. D. Luque de Castro* and M. Valc&aacute;rcel

Abstract: Sample was injected into a carrier stream of water or buffer solution, which was then merged with 0.08% p-rosaniline (C. I. Basic Red 9)/0.2% formaldehyde solution in dilute HCl (pH 0.4). The resulting solution passed through a reaction coil and switching valve to a flow cell containing Dowex 1-X8 anion-exchange resin (100-200 mesh) to retain the reaction product, the absorbance of which was measured at 560 nm. The valve was then switched to introduce 2 M HCl saturated with butanol into the cell as eluent. Response was linear for 0.16-6 µg/ml of SO2 and the detection limit was 49 ng/ml; the RSD over the calibration range was 2.4% (n = 11). The method was used to determine SO2 in wine; results on white and rose wines agreed well with those of a standard iodimetric method, but the method was inapplicable to red wine because tannins were retained on the resin.
Sulfur dioxide Spectrophotometry Sensor

"Monitoring Of Reducing Sugars By Flow Injection Analysis Using P-hydroxybenzoic Acid Hydrazide"
Anal. Chim. Acta 1994 Volume 285, Issue 1 Pages 1-8
Peter Hartmann, Stephen J. Haswell*, Manfred Grasserbauer

Abstract: Wine, beer, Lucozade and cola drinks were diluted with or without decolorization and banana, apple and kiwi fruit were homogenized, sonicated and filtered and injected into a water carrier stream. The solution merged with a pre-mixed stream of NaOH and p-hydroxybenzoic acid hydrazide (PAHBAH), passed through a reaction coil at 90-95°C and the absorbance measured at 410 nm. The concentrations and flow rates of NaOH and PAHBAH (listed) were optimized for three systems investigated: System A, non-catalyzed for glucose at high concentrations (0.025-1.5 g/l); System B, Bi(III) catalyzed for glucose at low concentration (4-40 mg/l); and System C, non-catalyzed for glucose and fructose (0.08-0.6 g/l). Standard calibration graphs (peak height) were linear (r = 0.9999) for the above concentration ranges and linear for fruit and beverages over the calibration range for System C with a RSD of 2%. Interference due to Ca(II) increased dramatically above 2 mM for System C and above 10 mM for System A and 20 ppm of glucose standard.
Fructose Glucose Spectrophotometry Interferences

"Determination Of Lead By Flow Injection Inductively Coupled Plasma Mass Spectrometry Comparing Several Calibration Techniques"
Anal. Chim. Acta 1994 Volume 293, Issue 1-2 Pages 171-181
Jan Goossens, Luc Moens and Richard Dams*

Abstract: A method for the determination of Pb in wine and urine was developed using a flow injection (FI) system coupled to ICP-MS. The FI system permitted online sample dilution and online internal standardization. Three calibration procedures were compared, viz., online isotope dilution, online standard additions and external calibration. The standard-additions method was preferred with respect to accuracy, precision and flexibility. The FI system was designed so the three streams (A, B and C at 0.6 ml/min each) were merged at two consecutive T-junctions. Streams A and C carried the sample and 50 µg/l of Tl solution (internal standard), respectively. A selector valve was fitted into the third channel so that stream B carried either 0.14 M HNO3 or 100 µg/l of Pb solution in 0.14 M HNO3 (for calibration). A 70 µL portion of the merged streams was injected into the primary carrier stream (0.14 M HNO3 at 1.5 ml/min), transported to the nebulizer and analyzed by ICP-MS. The 200-210 u mass range was scanned entirely. The method was applied to undiluted wines and standard reference urine samples.
Lead Mass spectrometry Mass spectrometry Standard additions calibration Reference material

"Air-segmented Flow Injection: A Hybrid Technique For Automated, Low Dispersion Determinations"
Anal. Chim. Acta 1995 Volume 303, Issue 2-3 Pages 231-239
Yunsheng Hsieh and S. R. Crouch*

Abstract: The hardware requirements of the title technique are discussed, and the degree of instrumental sample dispersion critically evaluated using 10 µM-phenol red in a borate buffer of pH 9.5. Applications of the technique to the analysis of glucose in wine and serum at 510 nm as previously described (Ibid., 1993, 284, 159) are presented, with a calibration graph linear over the range 10^-80 ppm glucose. Over the range 0.0093-0.42% glucose in wine, RSD (n = 5) of 0.46-0.78% were obtained. At 79 mg/dl glucose in serum an RSD (n = 5) of 3% was obtained.
Glucose Spectrophotometry Air segmentation Dispersion

"Flow Analysis With Membrane Separation And Time Based Sampling For Ethanol Determination In Beer And Wine"
Anal. Chim. Acta 1995 Volume 305, Issue 1-3 Pages 241-247
Jochen Mohns and Wolfgang K&uuml;nnecke*

Abstract: The flow analyzer. consisted of a dual-channel peristaltic pump, a gas diffusion unit incorporating a PTFE membrane (channel; 0.5 mm depth x 1.4 mm width x 21 mm length), an enzyme reactor containing 10 mg of alcohol oxidase immobilized on to controlled pore glass beads and an electrochemical detection cell operated at 700 mV. One channel of the pump propelled the acceptor stream (0.1 M potassium phosphate buffer at pH 7.5) through the gas diffusion unit and, after the switching of the appropriate valves, through the enzyme reactor and the detector cell. The other channel of the pump propelled samples and standard solutions through the donor channel of the gas diffusion unit. All flow rates were 1.5 ml/min. The flow of both donor and acceptor solutions was stopped to allow ethanol to diffuse across the PTFE membrane. The accumulated ethanol plug was then carried to the enzyme reactor where it was converted to acetaldehyde and H2O2. H2O2 was detected electrochemically. The thickness and pore size of the PTFE membrane controlled the diffusion of ethanol. With 550, 500 and 400 µm thick membranes, the calibration graphs were linear up to 0.6, 7 and 15% ethanol, respectively. The detection limit was 0.0001% ethanol. The RSD (n = 3) for the analysis of samples within the linear calibration range was 2%. The ethanol content of beer and wine samples were determined without sample pretreatment apart from manual degassing. The sampling frequency was 30 samples/h.
Ethanol Amperometry Controlled pore glass Immobilized enzyme Teflon membrane Gas diffusion

"Construction And Use Of A Tubular Picrate Ion-selective Electrode For Reducing Sugar Determination In Port Wine By Flow Injection Analysis"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 122-128
Teresa I. M. S. Lopesa, Ant&oacute;nio O. S. S. Rangela,*, Jos&eacute;L. F. C. Limab and M. Concei&ccedil;&atilde;o B. S. M. Montenegrob

Abstract: An FIA system equipped with a picrate ISE was described for the determination of reducing sugars in port wine. The determination was based on the reaction between the reducing sugars and picric acid and the measurement of the decrease in the picrate concentration by a tubular, flow-through detector. A 150 µL volume of wine was injected into a 0.045 M picric acid carrier stream (0.7 ml/min) which was merged with a 1.8 M NaOH stream (0.2 ml/min). After passing through a thermostatted water bath at 58°C, the flow was merged with a 1 M H2SO4 stream (0.2 ml/min). The flow passed through a 100 cm mixing coil to the detector. The calibration graph was linear for 25-200 g/l of reducing sugars and the RSD were 3.9%. The sampling frequency was ~e;50 samples/h. The results obtained for samples containing 98-148 g/l of reducing sugars were in agreement with those obtained by an iodometric reference method.
Sugars, reducing Electrode Electrode Method comparison Indirect Heated reaction

"A Stopped-flow/continuous-flow Method For Kinetic Determinations"
Anal. Chim. Acta 1995 Volume 309, Issue 1-3 Pages 277-282
Yun-Sheng Hsieh and S. R. Crouch*

Abstract: Using the kinetics of glucose (I) oxidation in wine as a model system, wine samples were diluted in phosphate buffer as described previously (Ibid., 1993, 284, 159), injected into carrier streams (0.16-0.98 ml/min) of air and buffer and detected at 510 nm with the detector placed within the sample loop. Calibration graphs were linear for 10^-80 ppm I. At ~0.44% and 0.019% of I in wine and using air- and buffer-carriers, RSD (n = 4 and 3) of 1.2% and 3.9%, and 1.5% and 1% were obtained, respectively. Method accuracy was assessed with the determination of I in standard sera, with an error of 8% (no details given). The use of acetone, ethanol, methanol and IBMK as carrier streams resulted in no significant system improvement.
Glucose Spectrophotometry Kinetic Optimization Stopped-flow MIBK Reference material

"Flow Injection Stopped-flow Spectrofluorimetric Kinetic Determination Of Total Ascorbic Acid Based On An Enzyme-linked Coupled Reaction"
Anal. Chim. Acta 1995 Volume 309, Issue 1-3 Pages 271-275
Houping Huang,*, Ruxiu Cai, Yumin Du and Yune Zeng

Abstract: Wine, beer or urine were adjusted to pH 6 with HCl or NaOH and 0.1 M EDTA added. Solid dose formulations of ascorbic acid were dissolved in 100 mL 1% oxalic acid and liquid formulations of ascorbic acid were diluted with water. To 1 mL portions containing ~0.5 µg/ml of ascorbic acid were added 5 µL aqueous 2 mg/ml of laccase and the solution injected in parallel with 10 mL 20 µM-o-phenylenediamine in 250 µM-phosphate buffer of pH 6 into a carrier stream (2 ml/min) of water and mixed in a 5 cm reaction coil at 35°C, and fluorimetric detection at 430 nm (excitation at 360 nm). Calibration graphs were linear for 0.025-1 µg/ml of ascorbic acid. Quantitative recoveries of ascorbic acid in the presence of Fe(III), Cu(II) and a range of common biochemical substrates were obtained, excepting L-cystine, L-cysteine, tyrosine and NH3OHCl.
Ascorbic acid, total Fluorescence Heated reaction Interferences Kinetic Stopped-flow

"Flow Injection Analysis With Chemiluminescent Detection Of Sulfite Using Sodium Carbonate-sodium Bicarbonate-copper Ion System"
Anal. Chim. Acta 1996 Volume 323, Issue 1-3 Pages 69-74
Jin-Ming Lin* and Toshiyuki Hobo

Abstract: An FIA system incorporating a gas diffusion cell is described for the selective determination of sulfite. A 100 µL sample was injected into a 0.1 M H2SO4 stream (0.5 ml/min) and transported to the cell, where the liberated SO2 diffused through a PTFE membrane (0.02 µm pore size, 45 µm thickness) and was collected in a 0.6 M Na2CO3 stream (0.5 ml/min). The collector stream was propelled to the chemiluminescence detector and mixed with a reagent stream formed by merging 0.4 M NaHCO3 and 0.5 mM Cu(II) (both at 1.5 ml/min). The light emitted was detected by a photomultiplier tube. The calibration graph obtained by plotting light intensity vs. log. sulfite concentration was linear for 1 µM-0.5 mM, the detection limit was 0.5 µM, and the RSD (n = 9) for 5 µM-sulfite was 4.6%. The method was applied to the determination of sulfite in wine following 100-500-fold dilution. The results were verified by a titration method with iodine.
Sulfite Chemiluminescence Gas diffusion Method comparison Teflon membrane

"Determination Of Sulfite In Wines By Gas Diffusion Flow Injection Analysis Utilizing Spectrophotometric PH-detection"
Anal. Chim. Acta 1997 Volume 337, Issue 2 Pages 125-131
L. G. Decnop-Weever* and J. C. Kraak

Abstract: A flow injection spectrophotometric method was developed for determining total sulfite in wines. The sample preparation procedure was carried out in a N2 atmosphere using a solution that had been degassed with N2. A wine sample of 25 mL was mixed with 50 mL of 10% ethanol and then 10 mL 2.5 M KOH was added. After 5 min, the following solutions were added in succession; 6.25 mL 2 M H2SO4 in 10% ethanol, 25 mL 2 M H2SO4 in 10% ethanol and sufficient 10% ethanol to give a total volume of 250 mL. A 40 µL portion of the resulting solution was immediately injected into a carrier stream (0.9 ml/min) of 1 M H2SO4 in 10% ethanol and passed through the donor channel of the gas diffusion cell. The SO2 diffused through the PTFE membrane and was collected in the acceptor stream (0.9 ml/min), 35 mg/l bromocresol green in 10% ethanol at pH 5.5. The absorbance of the acceptor stream was monitored at 620 nm. The method was calibrated for 1-20 mg/l sulfite and the detection limit was 0.1 mg/l. The method was applied to white, red and rose wines. The RSD (n = 6) for the peak heights was 0.7-1.5%. The recoveries of up to 7.5 mg/l sulfite from spiked wines were 96-109%. The sampling frequency was 120/h.
Sulfite Sample preparation Spectrophotometry Gas diffusion Teflon membrane pH

"Determination Of Trans-resveratrol And Other Polyphenols In Wines By A Continuous-flow Sample Clean-up System Followed By A Capillary Electrophoresis Separation"
Anal. Chim. Acta 1998 Volume 359, Issue 1-2 Pages 27-38
Lourdes Arce, Mar&iacute;a Teresa Tena, Angel Rios and Miguel Valc&aacute;rcel*

Abstract: A new method coupling flow injection (FI) with capillary electrophoresis (CE) was developed using diode array detection to measure the concentration. of trans-resveratrol in wines, in particular because of the interest in its biological properties and cancer prevention. A FI system furnished with a C-18 mini-column was used to clean up the wines by solid phase extraction prior to CE. The analytes were eluted from C-18 by using methanol and then driven from the FI system to the auto-sampler of the CE equipment by a programmable arm. The 3s detection limit ranged from 0.05 mg/L (trans-resveratrol) to 0.36 mg/L [(-)epicatechin]. The recoveries of added trans-resveratrol and other polyphenols from synthetic wines were between 92 to 110%, (mean of 99%). The method is faster and simpler than those previously reported which used liq.-liq. extraction and liquid chromatography
Polyphenols Trans-resveratrol Electrophoresis Spectrophotometry C18 Solid phase extraction

"Enzymic Determination Of L(+) Lactic And L(-) Malic Acids In Wines By Flow Injection Spectrophotometry"
Anal. Chim. Acta 1998 Volume 366, Issue 1-3 Pages 187-191
Jos&eacute; L. F. C. Limaa, Teresa I. M. S. Lopesb and Ant&oacute;nio O. S. S. Rangelb,*

Abstract: A flow injection system for the enzymatic determination of L(+) lactic acid and L(-) malic acid in wines with spectrophotometric detection is described. The samples are dialyzed inline, and the enzymes in solution (malate dehydrogenase and lactate dehydrogenase) are injected as a train of plugs in the acceptor stream of the dialysis unit, yielding two peaks corresponding to the NADH formed for each determination This methodology enables the determination of both acids with a single detector with a sampling rate of 20 h-1 (0.4-3 g L-1). The results are comparable to those obtained by the reference procedure, the repeatability is better than 5% (rsd), with low enzyme consumption (1.3 µL of suspension per sample).
l-Lactate l-Malic acid Spectrophotometry Enzyme Method comparison

"Automated Determination Of Sulfite And Sulfur Dioxide By Cool-flame Molecular-emission Spectrometry After Reduction To Hydrogen Sulfide With Sodium Tetrahydroborate(III)"
Talanta 1992 Volume 39, Issue 11 Pages 1471-1478
Toyin A. Arowolo and Malcolm S. Cresser*

Abstract: Sample was mixed with NaBH4, acidified with 6 M HCl and carried by a continuous-flow stream into a gas - liquid separator where the evolved H2S is swept by N into a cool H - N flame. The intensity of the blue diatomic S2 emission generated was measured at 384 nm. A schematic diagram of the apparatus is presented. The experimental conditions were optimized for the effects of HCl concentration, NaBH4 volume and concentration, sample volume, flow rates and flame composition. Calibration graphs for sulfite were rectilinear at 24 µg mL-1 with a detection limit of 29 ng mL-1 and the coefficient of variation were 1.2 and 1.5% for 1 and 5 µg l-1, respectively. Samples could be analyzed at a rate of ~40 h-1. Some interferences (notably from sulfide) were found, but the effects could be minimized; there was no interference from NO2. The method was applied to the determination of SO2 in air and sulfite in wines.
Sulfite Sulfur dioxide Spectrophotometry Interferences Optimization

"Simultaneous Determination Of Sulfite And Phosphate In Wine By Means Of Immobilized Enzyme Reactions And Amperometric Detection In A Flow Injection System"
Talanta 1994 Volume 41, Issue 12 Pages 2113-2119
Toshio Yao*, Masahiro Satomura and Taketoshi Nakahara,

Abstract: A flow-injection system is proposed for the simultaneous determination of sulfite and phosphate in wine. A sulfite oxidase immobilized reactor and purine nucleoside phosphorylase-xanthine oxidase co-immobilized reactor are incorporated at fixed positions (parallel configuration) in the flow line, which is based on the splitting of the flow after sample injection and subsequent confluence. A poly(1,2-diaminobenzene)-coated platinum electrode is used as an amperometric detector to detect selectively hydrogen peroxide generated enzymatically in the enzyme reactors, without any interference from oxidizable species and proteins present in wine. Because each channel has a different residence time, two peaks are obtained. The first peak corresponds to sulfite and the second peak to phosphate. The peak current is linearly related to the concentrations of sulfite between 1 x 10^-5 and 2 x 10^-3 M and phosphate between 2 x 10^-5 and 5 x 10^-3M. The simultaneous determination of sulfite and phosphate in wine can be performed at a rate of 30 samples/hr with satisfactory precision (less than 1.2% RSD) and no pretreatment except for the sample dilution.
Sulfite Phosphate Amperometry Immobilized enzyme Simultaneous analysis

"Pervaporation: An Integrated Evaporation/gas Diffusion Approach To Analytical Continuous Separation Techniques"
Talanta 1995 Volume 42, Issue 5 Pages 755-763
Ivanildo L. de Mattos*, M. D. Luque de Castro and Miguel Valc&aacute;rcel,

Abstract: A flexible pervaporation module was developed and characterized. The spacers it uses allows the volume of the donor and/or acceptor to be altered as required. The performance of the module was tested as regards both dynamic behavior and continuous pervaporation in terms of flow-rates, temperature, type of membrane, flow mode, etc. A method for the determination of ethanol in different types of wine was developed and applied to various samples in order to validate the proposed continuous separation approach.
Ethanol Gas diffusion Pervaporation

"Chemiluminometric Flow Injection Method For Determination Of Free L-malate In Wine With Co-immobilized Malate Dehydrogenase/NADH Oxidase"
Talanta 1995 Volume 42, Issue 11 Pages 1751-1755
Nobutoshi Kiba*, Junko Inagaki and Motohisa Furusawa

Abstract: Aminated poly(vinyl alcohol) beads were packed into a stainless-steel column (5 cm x 4 mm i.d.) and activated with 2.5% glutaraldehyde in 0.1 M phosphate buffer of pH 7. Enzyme solution (5 mg malate dehydrogenase; 600 iu and 5 mg NADH oxidase; 250 iu, in 10 mL 0.1 M phosphate buffer of pH 7) was circulated through the column for 6 h at a flow rate of 0.2 ml/min. A schematic diagram of the flow injection method is presented. Wine was introduced into the system and the H2O2 produced was detected chemiluminometrically via a luminol-hexacyanoferrate(III) reaction. The calibration graph was linear from 30 µM- to 25 mL-malate and the detection limit was 0.08 µM. RSD (n = 7) was 0.54%. Recoveries were 74-101%. Sample throughput was 30/h without carryover. The reactor was renewed every two weeks. A flow injection system with a co-immobilized malate dehydrogenase/reduced nicotineamide adenine dinucleotide (NADH) oxidase reactor and a chemiluminometer is described for the determination of free L-malate in wine. Malate dehydrogenase and NADH oxidase were co-immobilized on poly(vinyl alcohol) beads and packed into a stainless-steel column (5 cm times 4 mm i.d.). The hydrogen peroxide produced was detected chemiluminometrically via a luminol-hexacyanoferrate(III) reaction. The calibration graph was linear from 3 x 10^-7 M to 2.5 x 10^-4 M (the linear correlation coefficient was 0.9998); the detection limit (signal-to-noise ratio, 3) was 8 x 10^-8 M. The sample throughput was 30 h-1 without carryover. The reactor was renewed every 2 weeks.
l-Malate Chemiluminescence Immobilized enzyme Poly vinyl alcohol beads

"Chemiluminometric Method For The Determination Of Glycerol In Wine By Flow Injection Analysis With Co-immobilized Glycerol Dehydrogenase/NADH Oxidase"
Talanta 1996 Volume 43, Issue 10 Pages 1761-1766
Nobutoshi Kibaa,*, Naoki Azumaa and Motohisa Furusawaa

Abstract: Glycerol dehydrogenase and NADH oxidase were immobilized onto poly(vinyl alcohol) beads (details given) and packed into a stainless steel reactor column (4 cm x 4 mm i.d.) in a FIA system. Wine was diluted 1000-fold with water and injected into a carrier stream (0.2 ml/min) of water. Reagent streams of 1.5 mM NAD+ in 10 mM phosphate buffer of pH 7 (0.2 ml/min) and 1.5 mM luminol in 0.3 M carbonate buffer of pH 10 (0.2 ml/min) merged with each other and then with the carrier stream. The resulting stream passed through the enzyme reactor in a water bath at 30°C, merged with a reagent stream (0.2 ml/min) of 20 mM potassium hexacyanoferrate and passed through a mixing coil (60 cm x 0.5 mm i.d.). The chemiluminescence was measured in a flow-through cell. The calibration graph was linear for 0.3- 300 µM-glycerol with a detection limit of 70 nM. The RSD (n = 7) was 0.51% for 50 µM-glycerol. Sample throughput was 30/h.
Glycerol Chemiluminescence Immobilized enzyme Poly vinyl alcohol beads

"Online Coupling Of Gas Diffusion To Capillary Electrophoresis"
Talanta 1998 Volume 45, Issue 3 Pages 477-484
Petr Kuban and Bo Karlberg*

Abstract: Online gas diffusion has been coupled to a capillary electrophoresis system (CE) via a specially designed interface. The sample is merged with a modifying solution, e.g., a strong acid, in a flow system to transform the analytes of interest into their respective gaseous forms. These transformed, gaseous analytes permeate through a PTFE membrane into an acceptor stream comprising of a tris-buffer. The continuously flowing acceptor stream is led into an injector forming an integrated part of a flow injection analysis (FIA) system. The sample receiving carrier stream in the FIA system, a chromate buffer, brings the sample, 50 µl, to the FIA-CE interface into which one end of a separation capillary has been inserted. A small portion of the injected sample enters the capillary (electrokinetic injection) and separation takes place. A UV detector is placed at the other capillary end and a run potential of 25 kV is applied to two platinum electrodes positioned in the flow system. Multiple sample injections can be performed in one uninterrupted electrophoretic run. A typical sampling frequency is 15 h-1; each run may result in quantitation of at least five anions. The overall repeatability is in the range 1.8-3.6% (RSD). The technique has been applied to the analysis of real samples such as soft drinks, vinegar and wine. Selective discrimination of anions which are unable to form volatile species is accomplished. No off-line sample pre-treatment is needed.
Anions Electrophoresis Gas diffusion Interface Teflon membrane Volatile generation

"Determination Of Sulfur And Total Sulfur Dioxide In Wines By An ICP-AES Method"
Talanta 1998 Volume 45, Issue 6 Pages 1281-1284
I. Sarudi* and J. Kelemen

Abstract: Sulfur contents of the original sample and the sample free from sulfur dioxide were determined by ICP-AES following nitric acid digestion under high pressure (using PAAR HPA equipment), and the total sulfur content was calculated from the difference between the results obtained. With the aim of preparing a sample free from sulfur dioxide, bound sulfur dioxide was released by sodium hydroxide, then after acidifying by phosphoric acid, boiling was carried out. Relative standard deviations of the results obtained for total sulfur, the sulfur without S(IV) and total sulfur dioxide were lower than 2.5, 3.5 and 5% respectively. Various amounts of sulfur (in the form of Na2SO4), added to wine samples, were successfully recovered between 95.5 and 104.9%. Based on comparative analyzes performed by a widely accepted classic method, the indirect method developed was found to be adequate for the determination of total sulfur dioxide. The procedure is suitable for serial tests.
Sulfur Sulfur dioxide Spectrophotometry Sample preparation Method comparison

"Photometric Determination Of Tartaric Acid In Wine By Flow Injection Analysis"
Analyst 1986 Volume 111, Issue 7 Pages 729-732
Fernando L&aacute;zaro, M. D. Luque de Castro and Miguel Valc&aacute;rcel

Abstract: The wine sample in 0.7 M acetic acid was injected into the flow stream where tartaric acid(I) was complexed with VO3- from 6.6 mM NaVO3 in a solution buffered with Na acetate formed in situ. The absorbance was measured at 490 nm by using a Pye Unicam SP6-500 spectrophotometer equipped with a Hellma 178 12 QS flow cell. The influence of time and pH on the absorbance was studied and recoveries obtained (~102.5%) were compared with established methods (e.g., the Rebelein method). The calibration graph was rectilinear from 0.06 to 0.50 g L-1 of I with a coefficient of variation of 0.79%.
Tartaric acid Spectrophotometry Complexation Optimization

"Determination Of Ethanol Using Flow Injection Enthalpimetry"
Analyst 1988 Volume 113, Issue 2 Pages 359-360
Walace A. de Oliveira and Celio Pasquini

Abstract: Flow injection enthalpimetry was carried out by using the apparatus described previously (Anal. Chim. Acta, 1984, 156, 307). For the determination of ethanol in fuel-grade ethanol, both the carrier and diluent solution were anhydrous ethanol. Samples (100 µL) were introduced directly into the flow manifold (illustrated) and the resulting enthalpimetric peaks (from the heat of dilution of ethanol) were compared with those of standard solution. Results agreed well with those from a pyknometric method. For the determination of ethanol in wines and spirits, water was used as diluent and carrier and samples were distilled before analysis. The precision for ethanol concentration. of 6 to 12% ranged from 0.03 to 0.1%.
Ethanol Enthalpimetry Method comparison

"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 Spectrophotometry Stopped-flow Titrations

"Conductimetric And Spectrophotometric Determination Of The Volatile Acidity Of Wines By Flow Injection"
Analyst 1992 Volume 117, Issue 5 Pages 917-919
R&aacute;vio Guimar&atilde;es Barros and Matthieu Tubino

Abstract: The method previously described by the authors (J. Assoc. Off. Anal. Chem., 1991, 74, 346) was applied. It involved the diffusion of acetic acid through a membrane into a stream of water and a conductivity cell or into a stream of bromocresol purple, pH 7.0, and measurement at 540 nm. The calibration graphs were rectilinear, or nearly so, from 0.02 to 0.10 g per 100 mL. The spectrophotometric method was simpler but the conductimetric method was faster. The usual methods for the determination of the volatile acidity of wines are relatively slow. A method was developed which provides results in a much shorter time. About 60 analyzes can be performed in 1 h. The conductimetric anal. consists of the injection of the wine sample into a de-ionized water stream which then flows past a poly(tetrafluoroethylene) membrane separator. The HOAc diffuses through the membrane into another water stream that passes through a conductivity cell. The spectrophotometric method is similar. The HOAc diffuses into a stream of Bromocresol Purple solution, at pH 7.0, which passes through a flow cell in a spectrophotometer set at 540 nm. Anal. results were similar to those obtained by the method of Jaulmes.
Acidity Conductometry Spectrophotometry Method comparison Teflon membrane Gas diffusion

"Spectrophotometric Determination Of Biacetyl In Distillates Of Wine By Flow Injection"
Analyst 1992 Volume 117, Issue 8 Pages 1343-1346
Gloria del Campo and M. Carmen Lajo

Abstract: Biacetyl (I) was determined in wine by its reaction with 1-naphthol and creatine in alkaline medium. Reaction with the principal interferent, acetoin, was relatively slower so optimization of the flow injection conditions was used to increase the selectivity for I. A portion of wine steam distillate diluted with water was injected into a stream of 1-naphthol in NaOH and merged with a stream of creatine in NaOH at 0.4 mL min-1. The 280 cm long reaction coil was placed in a water bath at 35°C. The absorbance of the solution was measured at 520 nm and the sampling rate was 30 h-1. The calibration graph was rectilinear up to 10.0 µg mL-1 with coefficient of variation of 0.7 and 0.4% for 1.0 and 5.0 µg mL-1 of I standard, respectively (n = 10). For wine distillates, the coefficient of variation of the method was 2.7 to 3.3% and the recovery of I was 98 to 104%. The reaction of biacetyl with 1-naphthol (40 g/L) and creatine (6 g/L) in an alkaline medium was used to develop a flow injection method for the determination of biacetyl. The fact that biacetyl reacts comparatively faster than acetoin was exploited to minimize interference by acetoin; the optimum experimental conditions for increasing the selectivity were: temperature, 35°C; reaction coil length, 280 cm; flow rate, 0.4 mL/min; sample volume, 220 mm3. Under these conditions, the relationship between the peak height (absorbance), measured at 520 nm, and the concentration of biacetyl was linear up to 10.0 µg mL-1 with a relative standard deviation (RSD) of 0.74 and 0.37% for 1.0 and 5.0 µg mL-1 biacetyl standards (n = 10), respectively. The sampling rate was 30/h. When the method was applied to the determination of biacetyl in wine, after a separation step for biacetyl by steam distillation, the RSD was 2.7-3.3%, and the results were in good agreement with those obtained by a conventional spectrophotometric method. Recovery of biacetyl from wine samples spiked with 1.65 and 3.30 µg biacetyl/mL averaged 100.2%, with no serious interference from acetoin.
Biacetyl Spectrophotometry Interferences Optimization Heated reaction Method comparison

"Simultaneous Spectrofluorimetric Determination Of Glycerol And Ethanol In Wine By Flow Injection Using Immobilized Enzymes"
Analyst 1995 Volume 120, Issue 1 Pages 179-182
I. L. Mattos, J. M. Fernandez-Romero, M. D. Luque De Castro and M. Valc&aacute;rcel

Abstract: Wine was diluted 2500-fold in 100 mM KHCO3/Na2CO3 buffer of pH 10 (buffer A). Two volumes of the sample solution (150 and 50 µL for glycerol and ethanol determination, respectively) were injected via a dual injection valve into two symmetrical channels containing a reagent stream (0.6 and 1 ml/min) for glycerol and ethanol determination, respectively) of 4.5 mM β-NAD in buffer A. Each plug passed through a 1.5 cm long enzyme reactor (glycerol dehydrogenase or alcohol dehydrogenase immobilized on controlled-pore glass) maintained at 35°C. A coiled reactor (300 cm long) was inserted in the ethanol channel to produce a delay between the two streams subsequently merged and passed through a 50 cm long mixing coil before fluorimetric detection at 460 nm (excitation at 340 nm). A diagram of the manifold used is given. Calibration graphs were linear from 1-10 and from 10^-100 µg/ml of glycerol and ethanol, respectively. The RSD (n = 11) were 1%. Recoveries were 97-105%. The throughput was 60 samples/h.
Ethanol Glycerol Fluorescence Immobilized enzyme Controlled pore glass Heated reaction

"Direct Determination Of Free Sulfur Dioxide In Wine And Dried Apple Samples By Using A Gas Generating And Purging Device Coupled To A Continuous-flow (injection) System"
Analyst 1995 Volume 120, Issue 7 Pages 2013-2018
Zheng-liang Zhi, Angel R&iacute;os and Miguel Valc&aacute;rcel

Abstract: Two flow injection (FI) methods for the cited determination are described. In both methods a gas generating and purging device was incorporated in the FI manifolds, whereby the sample (2.5 mL of wine or 0.2-2 g of dried apple) was mixed with 0.8 mL of 1 M HCl in a reaction vessel kept at 65°C (method A) or 70°C (method B) to generate SO2. In method A, the SO2 was purged by a N2 stream (5 ml/min) and passed through a cuvette containing 1 mL of color-developing reagent (0.002% pararosaniline/1.5% formaldehyde/0.2 M HCl). The absorbance was measured continuously at 568 nm and the kinetic features of the absorbance-time (A-t) profiles were used for quantification of SO2. In method B, the SO2 was purged by an air stream (3 ml/min) and a portion (500 µL) of the gaseous sample was injected into a stream (0.7 ml/min) of the color-developing reagent downstream of the detector. By operating the FI manifold in flow-reversal mode, the sample was cycled such that A-t multipeak recordings were obtained at 568 nm on which quantification of SO2 was based. Calibration graphs were linear from 0.03 (detection limit) to 3 and from 0.75 (detection limit) to 75 µg/ml of SO2 for methods A and B, respectively. The RSD (n = 11) were 5-7% and the throughput was 10^-15 samples/h.
Sulfur dioxide Spectrophotometry Flow reversal Gas stream

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

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

"Flow-through Spectrofluorimetric Sensor For The Determination Of Glycerol In Wine"
Analyst 1995 Volume 120, Issue 12 Pages 2837-2840
Pilar Ca&ntilde;izares and M. D. Luque de Castro

Abstract: A flow-through sensor based on transient immobilization of NADH, the product of the reaction between glycerol and NAD(+) catalyzed by glycerol dehydrogenase, is proposed, The biocatalyst is immobilized on controlled-pore glass, where the enzymatic reaction takes place, the product of the reaction being transiently retained and spectrofluorimetrically monitored on passage through a flow cell packed with a solid support, The proposed method affords a linear range between 0.3 and 5.0 µg mL-1 of glycerol, and a detection limit of 0.1 µg mL-1, with a relative standard deviation of less than 2%, The performance of the sensor was checked by applying it to the determination of glycerol in wine. The results obtained agree well with those provided by a conventional method based on HPLC. (14 References)
Glycerol Fluorescence Sensor Immobilized enzyme Controlled pore glass Method comparison

"Vapor Generation Fourier Transform Infrared Direct Determination Of Ethanol In Alcoholic Beverages"
Analyst 1996 Volume 121, Issue 7 Pages 923-928
Amparo P&eacute;rez-Ponce, Salvador Garrigues and Miguel de la Guardia

Abstract: A procedure is proposed for the direct determination of ethanol in alcoholic beverages. The method is based on the injection of small volumes of untreated samples into a heated Pyrex glass reactor in which, at a temperature between 80 and 100°C, the ethanol is volatilized and introduced by means of a nitrogen carrier flow into a gas cell of an FTIR spectrometer. The measurement of the area of the flow injection recording, obtained from the absorbance of the transient signals, in the wavenumber range between 1150 and 950 cm-1, allows the direct quantification of ethanol without water background problems and free from interferences from sugars, providing a limit of detection of 0.02% v/v and typical RSDs between 0.11 and 0.5% for five analyzes of the same sample containing between 5 and 30% v/v ethanol. The sampling frequency of the method is 51 h-1 and accurate results were obtained for different types of alcoholic beverages, from low-alcohol beers to wines and spirits.
Ethanol Spectrophotometry Gas phase detection Interferences

"Flow Injection Determination Of Sulfite In Wines And Fruit Juices By Using A Bulk Acoustic Wave Impedance Sensor Coupled To A Membrane Separation Technique"
Analyst 1998 Volume 123, Issue 2 Pages 221-224
Xiaoli Su, Wanzhi Wei, Lihua Nie and Shouzhuo Yao

Abstract: A flow injection analysis (FIA) method was developed for the rapid determination of sulfite in wines and fruit juices. The method is based on an online membrane separation of the SO2 released from a stream of 0.5 M H2SO4 into a stream of 0.01 M H2O2-0.15 mM H2SO4. The conductance increase due to the oxidation of SO2 to H2SO4 is monitored by a bulk acoustic wave impedance sensor and the signal is proportional to the concentration. of sulfite present in the original sample. At a throughput of 78 samples h-1, the method exhibited a linear frequency response up to 1.0 mM sulfite with a detection limit of 5.0 µM, and the relative standard deviation of the peak height (n = 6) ranged from 0.57 to 1.23. Results obtained by the proposed method agreed well with those obtained by conventional iodimetry. The effects of several factors, including those affecting the detector performance and gas transfer process, on the performance of the proposed FIA system were also examined
Sulfite Sensor Conductometry Sensor Gas diffusion Method comparison Volatile generation Membrane Optimization

"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 Spectrophotometry Titrations Interferences Method comparison

"Speciation Analysis For Biomolecular Complexes Of Lead In Wine By Size-exclusion High-performance Liquid Chromatography-inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 8 Pages 749-754
Joanna Szpunar, Patrice Pellerin, Alexei Makarov, Thierry Doco, Pascale Williams, Bernard Medina and Ryszard Lobinski

Abstract: Size-exclusion chromatography with ICP-MS detection was developed for speciation of lead in wine. The method required minimal sample preparation and allowed routine anal. of wine samples, showing the distribution of lead among biomol. compounds within 30 min. The quantification of lead bound to biomolecules was done by comparing the chromatography peak area with that of a signal obtained by flow injection ICP-MS analysis. A study carried out on a population of 20 wines of different origin showed that mineral lead on which the toxicity conclusions were based may not exist in wine. Lead was found to be associated with one major biomol. (about 10 kDa) species present in all wine samples and one to three minor compounds whose number depended on the wine sample. The dominant species which accounted for 40-95% of lead was identified as the complex formed with the dimer of a pectic polysaccharide, rhamnogalacturonan II. Other minor species with apparent molecular masses in the range 500-3000 Da were not identified.
Lead Organometallic compounds SEC Mass spectrometry Speciation

"Doubly Stopped-flow. A New Alternative To Simultaneous Kinetic Multi-determinations In Unsegmented Flow Systems"
Anal. Chem. 1987 Volume 59, Issue 7 Pages 950-954
Fernando Lazaro, M. D. Luque de Castro, and Miguel Valcarcel

Abstract: A dual-injection system was used to analyze complex mixtures in which the determination of one of the analytes required a treatment step before the indicator reaction; twofold sequential stoppage of flow was also involved. The method was demonstrated by the simultaneous determination of free and total SO2 in wines and was based on the measurement at 578 nm of the compound formed by the analyte with formaldehyde and p-rosaniline. After injection of the sample into two channels, the stream for the determination of free SO2 was mixed with the reagent and was passed into the detector. In the other channel the bound SO2 was liberated with alkali before merging with the reagent and the product (total SO2) was passed into the detector after pumping out the first solution. Recoveries of added 2, 4 and 6 µg mL-1 of SO2 to five wines were between 92 and 106% with an average coefficient of variation of 3.6% (n = 10) for total SO2. The results for free SO2 were similar. The results agreed closely with those obtained by the method recommended by the EEC and were more precise.
Sulfur dioxide Spectrophotometry Kinetic Stopped-flow

"Individual And Simultaneous Determination Of Ethanol And Acetaldehyde In Wines By Flow Injection Analysis And Immobilized Enzymes"
Anal. Chem. 1987 Volume 59, Issue 14 Pages 1859-1863
Fernando Lazaro, M. D. Luque de Castro, and Miguel Valcarcel

Abstract: Ethanol(I) and acetaldehyde(II) in wine were determined individually on a straightforward flow injection analysis manifold with a suitable enzyme reactor by using immobilized alcohol dehydrogenase and acetaldehyde dehydrogenase (NAD(P)+), respectively, and detection at 340 nm. For the simultaneous determination, a dual injection valve was used that inserted the sample into different length channels, each containing an enzyme reactor. One peak per analyte was obtained. Calibration graphs for I and II, respectively, were rectilinear from 2 to 14 ppm (v/v) and 0.5 to 11.0 µg mL-1, and corresponding coefficient of variation were 0.6 and 0.5%. Results compared favourably with those obtained by using a dissolved enzyme technique.
Acetaldehyde Ethanol Spectrophotometry Dual valve Immobilized enzyme Tecator

"Determination Of Total And Free Sulfur Dioxide In Wine By Flow Injection Analysis And Gas Diffusion Using P-aminoazobenzene As The Colorimetric Reagent"
Anal. Chem. 1991 Volume 63, Issue 21 Pages 2532-2535
Jordi Bartroli, Manel Escalada, Cecilia Jimenez Jorquera, and Julian Alonso

Abstract: For the determination of free SO2, samples (0.3 ml) were injected into a stream of 0.6 M HCl, which then passed to the diffusion module, a poly(methacrylate) block, with a channel (7 cm x 2 mm) fitted with a gas-permeable poly(vinylidene fluoride) membrane. The SO2 diffusing across the membrane merged with the reagent stream, containing p-aminoazobenzene (I) and formaldehyde. The mixing coil after the diffusion module was 250 cm long to allow for the slow reaction of I with SO2. The reaction product was measured at 520 nm. For the determination of total SO2, samples (50 µL) were mixed with 4 M NaOH and the mixture passed into the loop of the injection valve, whence it was mixed with 0.6 M HCl as before. Agreement between direct and standard addition methods showed that there was no interference. Unlike p-rosaniline, the I was available pure commercially and the reagent solution was stable for at least a year.
Sulfur dioxide Spectrophotometry Diffusion Interferences Mixing coil Gas diffusion

"Mixed-valent Ruthenium Oxide-ruthenium Cyanide Inorganic Film On Glassy Carbon Electrodes As An Amperometric Sensor Of Aliphatic Alcohols"
Anal. Chem. 1995 Volume 67, Issue 1 Pages 101-107
Tommaso R. I. Cataldi, Diego Centonze, and Antonio Guerrieri

Abstract: For use in batch experiments, a clean vitreous carbon disc was cycled 25 times between -0.2 and +1.1 V vs. the SCE at 50 mV/s in a fresh solution of pH 2 containing 1 mM Ru3+ and Ru(CN)64-. It was then cycled similarly in 0.1 M H2SO4 at pH 2. Alternatively, an electrode was maintained at +1.05 V for 5-30 min in the fresh Ru solution and subsequently used in a flow cell for amperometric detection. Aliphatic alcohols were determined by FIA with 25 mM H2SO4 as electrolyte and carrier (0.5 ml/min) and detection at +1.05 V vs. Ag/AgCl; mixtures were separated at room temperature on a 10 µm Polipore H reversed-phase ion-exchange column (22 cm x 4.6 mm i.d.) with 25 mM H2SO4 as mobile phase (0.4 ml/min) and detection at +1-1.05 V vs. Ag/AgCl. In FIA, the mean current recorded for 5 mM butanol was 4.3 µA and the RSD was 6% (n = 5). The modified electrodes were applied in the LC analysis of beer and wine.
Alcohols, aliphatic Butanol, 1- Amperometry Electrode Sensor

"A Bienzyme Electrode Probe For Malate"
Anal. Chem. 1996 Volume 68, Issue 2 Pages 360-365
M. C. Messia, D. Compagnone, M. Esti, and G. Palleschi

Abstract: A new amperometric malate enzyme electrode probe has been constructed using a hydrogen peroxide-based sensor coupled with malic and pyruvate oxidase enzymes. The first enzyme catalyzes the oxidation of malic acid, which in the presence-of NADP(+) yields pyruvate as product. The oxidation of pyruvate is catalyzed by pyruvate oxidase, which yields H2O2 as product in the presence of O-2 and phosphate as cosubstrates and thiamine pyrophosphate and Mg2+ as cofactors. The H2O2 is then detected by the electrochemical transducer, and the output current changes are correlated to the concentration of malic acid in solution. Analytical parameters such as pH, temperature, buffer, substrate and cofactor concentrations, and response time have been optimized, Probe stability and reproducibility have been evaluated. The malic enzyme was used first in solution and then coimmobilized with pyruvate oxidase, Coimmobilization of the oxidase and dehydrogenase enzymes has been performed both randomly and asymmetrically on different supports, Calibration curves for malate have been constructed with all the analytical parameters optimized. The detection limit for this newly designed probe was 5 x 10^-7 mol/L, with a broad linear range between 10^-6 and 5 x 10^-4 mol/L. Recovery studies of malate in a wine matrix have been carried out. Malic acid has been determined in grape musts during grape maturation, Results correlated well when compared with those from a spectrophotometric procedure.
l-Malate Amperometry Electrode Interferences Immobilized enzyme Method comparison

"Flow Injection - Based Renewable Electrochemical Sensor System"
Anal. Chem. 1996 Volume 68, Issue 21 Pages 3808-3814
Michael Mayer and Jaromir Ruzicka

Abstract: A renewable electrochemical sensor was developed in which electrically conducting beads formed the disposable electrode and enzymes immobilized on to non-conducting beads formed renewable enzymatic layers. The sensor was based on a sequential injection system equipped with planar concentric Pt electrodes mounted at the base of a stainless steel tube. The central electrode (5.5 mm2) was the working electrode and the beads were piled on to this electrode to form a packed-bed column. The outer Pt electrode (2.8 mm2) was the quasi-reference electrode and the steel tube was the counterelectrode. Each measurement was carried out by injecting a suspension of beads into the stainless steel column to form a packed bed. The analyte was then injected into the carrier stream and transported through the beads. Detection was by measuring the oxidation current. The approach was tested using different immobilized oxidases (galactose, lactate, alcohol or glucose) and various conducting and non-conducting beads (controlled pore glass, oxirane acrylic, glassy C and graphite). Detection limits were 0.085 and 0.005 mM alcohol, and galactose, glucose and lactate, respectively. The approach was applied to determine glucose and alcohol in beer and wine samples.
Alcohol Glucose Sensor Controlled pore glass

"Comparison Of Ion Chromatography And Atomic Absorption Spectrometry For Metal-ion Analysis In Wine And Fruit Juices"
Fresenius J. Anal. Chem. 1985 Volume 322, Issue 5 Pages 474-479
Da-ren Yan, E. Stumpp und G. Schwedt Contact Information

Abstract: Copper, Zn, Fe, Mn, Ca and Mg were determined in wines and fruit juices by ion chromatography and AAS; the results were compared. The chromatographic separation was optimized for a Nucleosil SA-10 column (25 cm x 4 mm) with a mobile phase (2 mL min-1) of 1.5 mM oxalic acid - 2 mM ethylenediamine at pH 3.5. Post-column derivatization was carried out with 0.25 mM 4-(2-pyridylazo)resorcinol containing Zn and EDTA; detection was at 490 nm. Results were comparable with those obtained by AAS between 213.86 and 422.67 nm.
Copper Calcium Iron Magnesium Manganese Zinc HPIC Spectrophotometry Spectrophotometry Method comparison Post-column derivatization

"Digestion-free Determination Of Trace Metals In Beverages By Inverse Voltammetry In Flow-through Cells"
Fresenius J. Anal. Chem. 1987 Volume 327, Issue 2 Pages 175-178
Faramarz Wahdat und Rolf Neeb

Abstract: Digestion-free determination of trace-metals (Zn, Cd, Pb, Cu) in beverages by inverse voltammetry in a flow-through cell equipped with a mercury film-electrode is described. Optimal enrichment potentials are obtained by inspection of the pseudopolarograms of the elements in the original diluted sample solution. After the deposition step in the untreated sample solution stripping is effected in a proper supporting electrolyte after medium exchange. Values obtained by this techniques with various samples compare well with those obtained by usual procedures including wet digestion of the samples.
Cadmium Copper Lead Zinc Voltammetry Flowcell

"Determination Of Sulfite In Wine By Flow Injection Analysis With Indirect Electrochemical Detection"
Fresenius J. Anal. Chem. 1994 Volume 349, Issue 6 Pages 469-472
N. T. K. Thanh, L. G. Decnop-Weever and W. T. Kok

Abstract: Wine was diluted 50-100-fold with 0.1 M H2SO4 in 10% ethanol. A 0.13 l portion was injected into a carrier of the same composition as the diluent. The carrier flowed over a 45 µm thick permeable PTFE membrane and the SO2 diffused into an acceptor stream of acetate buffer of pH 4.7. This merged with a reagent stream, containing 5 mM KI, which was oxidized electrochemically at 5 or 25 µA, to provide an iodine solution All streams were pumped at 0.5 ml/min; this gave an iodine concentration of 0.78 or 3.9 µM. After the reaction with SO2, the unconsumed iodine was detected amperometrically. With the 5 µA generating current, the linear range was 0.05-2 ppm; at 0.9 ppm, the RSD was 1.6%. The results compared well with those obtained by titrimetry.
Sulfite Amperometry Indirect Method comparison Teflon membrane Gas diffusion Electrochemical product conversion

"Determination Of Antimony In Wine By Hydride Generation Graphite Furnace Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 1 Pages 92-96
Anne-Marie Wifladt A, Grethe Wibetoe A, W. Lund

Abstract: A method was developed for the determination of Sb in wine by electrothermal atomic absorption spectrometry, based on pre-concentration by hydride generation with collection directly in the graphite furnace. Thiourea was added for prereduction of Sb(V) to Sb(III). The hydride was directly generated from diluted wine. Palladium was used as modifier in the collection step; the overall efficiency of the hydride/trapping system was found to be 67%. Sb was determined in several samples of red wine; the concentrations found were in the range 0.6 to 5.7 µg/L Sb. The detection limit of the method was 39 pg Sb, corresponding to 0.13 µg/L Sb in wine when 0.3 mL wine was analyzed.
Antimony Spectrophotometry Volatile generation Volatile generation

"A Rapid Automated Method For Wine Analysis Based Upon Sequential Injection (SI)-FTIR Spectrometry"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 1 Pages 130-136
R. Schindler, R. Vonach, B. Lendl, R. Kellner

Abstract: A new process control methodology for the simultaneous determination of sugars, alcohols, and organic acids in wine based on multivariate evaluation of mid-IR transmission spectra of wine samples is presented. In addition to EtOH several lower level wine components (glucose, fructose, glycerol, citric- , tartaric-, malic-, lactic-, and acetic acid) were determined To establish a multivariate calibration model a set of 72 calibration solutions was prepared and measured, using a novel, fully automated sequential injection (SI) system with Fourier transform IR (FTIR) detection. The resulting spectra were evaluated using a partial least square (PLS) model. The developed PLS model was then applied to the anal. of real wine samples containing 79-91 g L-1 EtOH, 5.9-8.1 g L-1 glycerol, 0.4-6.9 g L-1 glucose, 1.5-7.5 g L-1 fructose, 0.3-1.6 g L-1 citric acid, 1.0-1.7 g L-1 tartaric acid, 0.02-3.2 g L-1 malic acid, 0.4-2.8 g L-1 lactic acid, and 0.15-0.60 g L-1 acetic acid, yielding results which were in good agreement with those obtained by an external reference method (HPLC-IR). The short analysis time (<3 min) together with high reproducibility makes the newly developed method applicable to process control and screening purposes (av. of the standard deviations calculated from four repetitive measurements of 6 different real samples: EtOH: 0.55 g L-1, glycerol: 0.037 g L-1, glucose: 0.056 g L-1, fructose: 0.036 g L-1, citric acid: 0.020 g L-1, tartaric acid: 0.010 g L-1, malic acid: 0.052 g L-1, lactic acid: 0.012 g L-1, and acetic acid: 0.026 g L-1).
Sugars Alcohol Acids, organic Ethanol Glucose Glycerol Fructose Citric acid Tartaric acid l-Malic acid Lactic acid Acetic acid Spectrophotometry Sequential injection Method comparison Simultaneous analysis Multivariate calibration Partial least squares

"Chemiluminescence Determination Of Sulfite In Sugar And Of Sulfur Dioxide In Air Using The Tris(2,2 '-bipyridyl)ruthenium-KIO4 System"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 7-8 Pages 566-570
F. Wu, Zhike He, H. Meng, Liangjie Yuan, Xiaoyan Li, Yun'e Zeng

Abstract: The chemiluminescence (CL) detection for the determination of sulfite using the reaction of Ru(bipy)(3)(2+)(bipy=2,2'-bipyridyl)-SO32--KIO4 is described. The concentration of sulfite is proportional to the CL intensity from 1.0 x 10^-7 to 1.0 x 10^-4 mol/L. The limit of detection is 2.0 x 10^-8 mol/L and the relative standard deviation is 4.4% for a 2 x 10^-5 mol/L sulfite solution (n = 9). This method has successfully been applied to the determination of sulfite in powdered sugar (sucrose) and of sulfur dioxide in air by using triethanolamine (TEA) as absorbent material.
Sulfite Sulfur dioxide Chemiluminescence

"Spectral And Non-spectral Interferences In Inductively Coupled Plasma Mass Spectrometry"
Microchim. Acta 1995 Volume 119, Issue 3-4 Pages 277-286
Richard F. J. Dams, Jan Goossens and Luc Moens

Abstract: An overview is presented on the identification and elimination of interferences in ICP-MS. Elimination of spectral interferences by anion exchange, matrix modification and mathematical correction are discussed. Calibration methods, adapted sample preparations and flow injection techniques for the elimination of nonspectral interferences are then considered. Applications of the correction methods to the analysis of water, soil, sewage, urine, serum and wine are described. (50 references).
Mass spectrometry Sample preparation Interferences Matrix removal Review

"Flow Injection Analysis Of Wine - Accomplishments And Needs"
Microchem. J. 1992 Volume 45, Issue 2 Pages 114-120
Katja Wagner, Ursula Bilitewski and Rolf D. Schmid*

Abstract: A general review is presented, with 37 references, covering the application of flow injection analysis to the analysis of wine components and comparing them with conventional techniques. State-of-the-art methods are presented in the form of tables. A general review with 37 references is presented concerning the need for wine analysis and the application of flow injection analysis (FIA) for the determination of wine components. The state-of-the-art is presented in the form of tables. Different types of methods and systems are described and compared with conventional techniques. Some improvements in this field of research are also mentioned.

"L-Malate Determination In Wines And Fruit Juices By Flow Injection Analysis. Adaptation Of A Coupled Dehydrogenase - Transferase System"
Anal. Lett. 1989 Volume 22, Issue 15 Pages 2897-2913
Chemnitius, G.C.;Schmid, R.D.

Abstract: Malate dehydrogenase and aspartate aminotransferase were co-immobilized on controlled-pore glass; the carrier stream (0.1 M K phosphate of pH 7.0) contained NAD+ to generate oxalacetate (I) and NADH from L-malate and the first enzyme, and L-glutamate to trap I with the second enzyme. The NADH was detected fluorimetrically. The rectilinear range was 5 to 100 µM-L-malate, but up to 50 mM L-malate could be determined directly by zone sampling, a flow injection configuration which is described. From 12 to 20 samples could be analyzed per hour. Results agreed with those obtained by an official method.
l-Malate Fluorescence Controlled pore glass Immobilized enzyme Method comparison Standard method Zone sampling

"New Chemiluminometric Method For The Determination Of Glycerol In Wine By Flow Injection Analysis With Immobilized Glycerol Dehydrogenase In Combination With NADH Oxidase"
Anal. Lett. 1994 Volume 27, Issue 8 Pages 1489-1505
Kondruweit, S.;Dremel, B.A.A.;Schmid, R.D.

Abstract: Wine (100 µL) and 40 µL of aqueous 5 mM NAD+ were introduced into a stream (0.8 ml/min) of 0.1 M potassium phosphate buffer of pH 9 containing 0.02% sodium azide (buffer A) and, for fluorimetric determination, carried to an enzyme reactor (30°C) containing glycerol dehydrogenase (GDH) immobilized onto controlled-pore glass with glutaraldehyde, where glycerol was converted to dihydroxyacetone; the NADH produced was detected at 460 nm (excitation at 340 nm). The calibration graph for glycerol is shown; no detection limit or RSD are given. For chemiluminometric (CL) determination, the sample first passed to an enzyme reactor (30°C) containing immobilized GDH, and then to a reactor (30°C) containing immobilized NADH oxidase, before merging with pre-mixed streams of 0.8 mM luminol and 40 mM potassium hexacyanoferrate(III), both in buffer A, for detection of H2O2. The calibration graphs for H2O2 and glycerol are shown and the detection limits were 1 nM and 25 µM, respectively; the working range was from 0.1-10 mM glycerol (RSD 2%). For both systems, sample throughput was 40/h.
Glycerol Fluorescence Chemiluminescence Controlled pore glass Immobilized enzyme

"Alcohol Electrodes In Beverage Measurements"
Anal. Lett. 1994 Volume 27, Issue 15 Pages 3027-3037
Rebelo, M.J.F.;Compagnone, D.;Guilbault, G.G.;Lubrano, G.J.

Abstract: Alcoholic beverage (50-200 µL) was added to 5 mL 0.1 M phosphate buffer of pH 8 (or to 200 µL of diluted buffer for beverages of >20% alcohol content) and a peroxide system alcohol sensor was dipped in the solution with stirring. The steady state current was measured and the background current was subtracted. The calibration graph was linear for 50-700 mg/dl of ethanol; the RSD (n = 3-5) was 0.2-0.84%. The electrode was used in a wall jet mode FIA system. Beverages diluted in 0.1 M phosphate buffer of pH 8 (100 µL) was injected into a phosphate buffer carrier stream at 1 ml/min. The calibration graph was linear for 60-300 mg/dl of ethanol with RSD (n = 10) of 0.4%. The results from the analysis of wines, beers, liqueur, port and vodka were compared with those obtained by the Sigma ethanol test kit. The batch method results agreed well with those reported by the beverage manufacturers.
Ethanol Electrode Steady state Method comparison

"Cyclic Enzymatic Determination Of L-lactate By Differential PH Measurement"
Anal. Lett. 1995 Volume 28, Issue 14 Pages 2475-2490
Compagnone, D.;Mosca, A.;Palleschi, G.

Abstract: An electrochemical procedure for the analysis of L-lactate based on the lactate dehydrogenase/lactate oxidase reaction cycle has been developed and applied in whole blood and wine. The reaction of lactate with lactate oxidase produces pyruvate, which is the substrate, at physiological pH, of the enzyme lactate dehydrogenase. This enzyme, in the presence of NADH, converts pyruvate to lactate consuming H+. An automated software controlled differential pH meter was used for H+ detection and the Delta pH measured was correlated to the lactate concentration present in the sample. (24 References)
l-Lactate Electrode Potentiometry Immobilized enzyme Indirect

"An Enzymatic Method For The Determination Of ATP And Glycerol With An Automated FIA System"
Anal. Lett. 1997 Volume 30, Issue 3 Pages 537-552
E. R. Kiranas; M. I. Karayannis; S. M. Tzouwara-Karayanni

Abstract: The flow manifold was equipped with two enzyme reactors coupled in series containing glycerol kinase (GK) and glycerol-3-phosphate oxidase (GPO) immobilized on to non-porous glass beads. The glycerol assays were performed by injecting 85 µL sample solution into a carrier stream of Tris/HCl buffer of pH 8.2 at a flow rate of 0.45 ml/min. The carrier stream was merged with a reagent stream, at a flow rate of 0.06 ml/min, containing ATP/MgCl2 (1:17). The mixture was passed through the GK reactor where glycerol was phosphorylated to produce α-glycerophosphate (α-GP). The flow was then passed through the GPO reactor where α-GP was oxidized to dihydroxyacetone phosphate producing H2O2. Detection was at 510 nm by merging the flow with a colorimetric reagent at a flow rate of 0.06 ml/min containing horseradish peroxidase/4-aminoantipyrine/3.5-dichloro-2-hydroxymethyl sulfonic acid. To determine ATP the first reagent was changed to glycerol/MgCl2. Calibration graphs were linear from 4-70 and 2-160 µM ATP and glycerol, respectively. The method was applied to the determination of glycerol in wines following a 1:5100 dilution and in human serum following deproteinization by gel filtration.
Adenosine-5'-triphosphate Glycerol Spectrophotometry Immobilized enzyme Glass beads

"Computerized Potentiometric Stripping Analysis Using Asyst Software: Application To Lead Determination In Wines And Vinegars"
Electroanalysis 1989 Volume 1, Issue 2 Pages 177-180
Saverio Mannino*, Giuseppe Fregapane, Mariagrazia Bianco

Abstract: A computerized system for potentiometric stripping analysis made of commercially available components with corresponding software is described. Application to the determination of lead in wines and vinegars is also reported.
Lead Potentiometric stripping analysis Computer

"Enzymic Determination Of Ethanol By Flow Injection Analysis Using A Kel-F Wax - Carbon-paste Electrode"
Electroanalysis 1991 Volume 3, Issue 7 Pages 625-630
Julie Wangsa, Neil D. Danielson

Abstract: The electrode was prepared from graphite powder and Kel-F wax in the wt. ratio 1.25:1. The graphite powder was first treated with hexane folowed by CHCl3, acetone and 6 M HNO3 and then dried at 100°C. This pre-treatment improved the reponse of the Kel-F wax - carbon-paste electrode by ~36% and improved electrode-to-electrode reproducibility. The graphite powder was added slowly with stirring to the melted Kel-F. After cooling and further mixing, a small amount of the paste was packed into the flow cell cavity, and the electrode surface was flattened and polished. The freshly prepared electrode was equilibrated for ~8 h by flow injection in the presence of buffer. Generally, the carrier solution used for standards and samples contained 20 iu mL-1 of alcohol dehydrogenase, 1.25 mM NAD+ and 2% (w/v) of polyoxyethylene glycol (to stabilize the enzyme) in 0.05 M Tris - HCl buffer (pH 8.0). Wine samples were diluted by a factor of 200 before analysis. The calibration graph was rectilinear from the detection limit of 0.44 mM to 33 mM.
Ethanol Electrode Buffer Graphite Heated reaction Enzyme

"Simultaneous Flow Injection Analysis For L-lactate And L-malate In Wine Based On The Use Of Enzyme Reactors"
Electroanalysis 1992 Volume 4, Issue 5 Pages 545-548
Shuichi Yoshioka, Hiroyuki Ukeda, Kiyoshi Matsumoto, Yutaka Osajima

Abstract: Malate dehydrogenase and diaphorase were co-immobilized on CNBr-activated Sepharose 4B; lactate oxidase was immobilized on Amino-Cellulofine. The product was packed into a glass tube (10 cm x 2 mm) to form a reactor for malate or lactate, respectively, which was incorporated into one line of a flow injection system operated at 20°C. The sample solution was diluted with 0.05 M pyrophosphate buffer of pH 9.0 and saturated with menadione, then pumped through the sample loop (150 µL) of the lactate line and mixed with 5 mM NAD+ in the same buffer before reaching the sample loop (150 µL) of the malate line. By means of a 16-way switching valve, sample solution was simultaneously injected into the two lines and transported by a stream (2.0 and 1.0 mL min-1 in the lactate and the malate line, respectively) of the pyrophosphate buffer saturated with menadione to the enzyme reactors and thence to an O electrode operated at -0.8 V for amperometric measurement. Peak currents were rectilinearly related to concentration. for 0.05 to 1.2 mM L-malate and 0.01 to 0.5 mM L-lactate. Sampling frequency was 15 h-1. The method was used for determining both analytes in wine; red wines were pre-treated with gelatin to remove polyphenols. Results agreed with those obtained by the conventional F-kit method. The simultaneous determination of L-malate and L-lactate, by enzyme-supported flow injection analysis was developed using 2 enzyme reactors in parallel and a single O2 electrode. NADH formed in the reaction of malate dehydrogenase (MDH) was regenerated to NAD+ with dissolved O2, using vitamin K3 and diaphorase (DI). L-Lactate was determined using the enzyme lactate oxidase (LOD). When sample solutions were simultaneously injected into the 2 reactors (the MDH-DI-reactor and the LOD-reactor) with a controlled residence time, a train of 2 peaks corresponding to L-lactate and L-malate was seen. The peak currents were linearly related to the L-malate and L-lactate concentration. in the range 0.05-1.2 mM and 0.01-0.5 mM, respectively. The present system was applied to the determination of L-lactate and L-malate in wine. The results showed good agreement with those obtained using a conventional method (F-kit method), suggesting that this system may be applicable to the monitoring of malolactic fermentation during wine prodn.
l-Lactate l-Malate Amperometry Electrode Reactor Immobilized enzyme Sepharose beads Merging zones Method comparison

"Potentiometric Detectors For The Determination Of Acidity By Discontinuous Flow Analysis"
Electroanalysis 1992 Volume 4, Issue 8 Pages 805-810
Terence J. Cardwell, Robert W. Cattrall, Gregory R. O'Connell, John D. Petty, Geoffrey R. Scollary

Abstract: Three potentiometric detectors, each incorporating a vibrating reed mixer, were investigated for use in the determination of acidity by discontinuous flow anal. (DFA). Two of these used PVC and glass membrane pH-sensors, and the third employed a novel differential titration technique based on two quinhydrone electrodes. These detectors were applied to the determination of the total acidity of vinegars and the titratable acidity of wines, the results agreeing well with standard procedures. The anal. of wine proved to be difficult because of the gradual change in pH at the end-point and so a method was developed which determined the titratable acidity at pH 8.3.
Acidity Electrode Electrode Potentiometry Mixing Method comparison

"Flow Injection Analysis Of Ethanol With An Alcohol Dehydrogenase-modified Carbon Paste Electrode"
Electroanalysis 1996 Volume 8, Issue 10 Pages 932-937
M. Jesus Lobo, Arturo J. Miranda, Paulino Tu&ntilde;&oacute;n*

Abstract: An amperometric ethanol sensor based on carbon paste, chemically modified with alcohol dehydrogenase, nicotinamide adenine dinucleotide and Toluidine Blue O as a mediator, is described. The surface of the sensor is protected by covering with a dialysis membrane. Dialysis membranes with different molecular weight cut-off were tested for preventing leaching of soluble species from the electrode. The influence of various experimental conditions was investigated for optimum analytical performance. Linear responses for ethanol in the range 2 times 10^-5 M to 2.4 times 10^-4 M at 0.05 V (Ag/AgCl) and a response time of 60 s were obtained. The sensor was also used in flow injection analysis and tested on wine samples. Modified carbon paste was prepared from graphite powder/paraffin oil mixture containing 10% toluidine blue O, 5% alcohol dehydrogenase and 10% nicotinamide adenine dinucleotide. The paste was packed into the body of the working electrode and covered with a dialysis membrane. Cyclic voltammetric measurements were made in 0.1 M phosphate/citrate buffer of pH 8.5 with Ag/AgCl and a Pt wire electrode served as the reference and counter electrodes, respectively. Amperometric measurements for addition of suitable portions of standard ethanol (I) solutions were made at an applied potential of 50 mV. The calibration graph was linear up to 24 µmM I with a detection limit of 8.7 µM. FIA was effected with the supporting electrolyte buffer containing 0.7 M NaCl as the carrier solution (0.5 ml/min). The sensor was stable for, at least, 1 month.
Ethanol Electrode Electrode Sensor Optimization Dialysis

"The Determination Of Ethanol In Wine By Voltammetry With An Internal Standard"
Electroanalysis 1997 Volume 9, Issue 7 Pages 544-548
Ji Jin Yu, Weiguang Huang, D. Brynn Hibbert*

Abstract: A rapid method for the electroanalysis of ethanol is presented that incorporates flow extraction at room temperature, with voltammetric detection and potassium ferrocyanide as internal standard. in 0.1 M NaOH electrolyte, ethanol was oxidized at a platinum comb-shaped working electrode at -300 mV (vs. a Ag/AgCl reference electrode) and K4Fe(CN)(6) was oxidized at +180 mV. The ratio of the anodic peak currents was Linear with ethanol concentration in the range of 0.1 to 8.0% (v./v.), and the detection limit (calculated as 3s background) was 0.012 % (v./v.) for Osteryoung square wave voltammetry (OSWV) and 0.023 %(v./v.) for cyclic voltammetry (CV). The average extraction efficiency of ethanol from aqueous solutions, at 20±1°C, was 8.5%. The repeatability was in the range of 2.5 to 3.3% RSD (n = 8), and accuracy was in the range of 95.2 to 104.7% for the determination of wine samples. Application to wines compared well with GC and HPLC methods and the nominal ethanol concentration determined by gravimetry. Analytical parameters in CV and OSWV are optimized, and the dependence of the extraction efficiency with temperature and nitrogen gas flow is presented. 20 References
Ethanol Amperometry Voltammetry Electrode Sample preparation Extraction Optimization Method comparison

"Flow Injection, Amperometric Determination Of Ethanol In Wines After Solid-phase Extraction"
Electroanalysis 1997 Volume 9, Issue 7 Pages 541-543
Zuliang Chen, Ji Jin Yu, D. Brynn Hibbert*

Abstract: Wine (0.5 ml) was diluted with water (1 ml) and purified on a Super Clean LC-SAX anion exchange-cartridge by elution with 2 mL water. A portion of the eluate was injected into a stream (0.5 ml/min) of 0.1 M NaOH of a FIA system. Detection was effected with a Ni wire working electrode, a Ag/AgCl reference electrode and a Pt wire counter electrode. A potential of +0.6 V was applied to the working electrode. The detection limit was 1 µM-ethanol. The response was linear up to 1 mM. Recoveries ranged from 100.8-102.9%.
Ethanol Amperometry Electrode Ion exchange Sample preparation Extraction

"Graphite-Teflon-peroxidase Composite Electrodes"
Electroanalysis 1997 Volume 9, Issue 14 Pages 1113-1119
Maria Antonia del Cerro, Gabriela Cayuela, A. Julio Reviejo, Jose M. Pingarr&oacute;n *, Joseph Wang

Abstract: The performance of graphite-70% Teflon-peroxidase-ferrocene composite electrodes, fabricated by simple physical inclusion of the enzyme and the mediator into the bulk of a graphite-Teflon matrix, by using both batch and flow injection modes, is reported. The electrode responds very rapidly to changes in H2O2 concentration due to the absence of a membrane barrier on the electrode surface and of a covalent attachment of the enzyme to graphite. The composite enzyme electrode showed a long-term operation due to the renewability of its surface by polishing. Reproducible amperometric responses were achieved with different electrodes fabricated from different composite matrices, and no significant loss of the enzyme activity was observed after seven months of dry-storage at 4°C. A bienzymatic graphite-70% Teflon-peroxidase-glucose oxidase-ferrocene electrode has been developed, too, showing a rapid response to the changes in the glucose concentration. The stability of the bienzymatic composite electrode was similar to that of the peroxidase biosensor. This biosensor was applied to the determination of glucose in must and wine samples by batch amperometry and flow injection with amperometric detection modes.
Glucose Amperometry Electrode Sensor Electrode Electrode Apparatus

"Determination Of Biogenic Amines In Cheese And Some Other Food Products By High Performance Liquid Chromatography In Combination With Thermo-sensitized Reaction Detection"
J. Chromatogr. A 1986 Volume 356, Issue 2 Pages 311-319
H. M. L. J. Joosten and C. Olieman

Abstract: Biogenic amines were extracted from cheese, chocolate, fish, wine and sauerkraut by precipitation with trichloroacetic acid before HPLC on a radial-compression cartridge (10 cm x 8 mm) packed with Nucleosil C18 and equipped with a pre-column of Corasil C18. The mobile phase was aqueous 47% dimethyl sulfoxide containing 1 g L-1 of Na dodecyl sulfate and 2.8 M in Na acetate buffer (pH 5); ninhydrin (8 g l-1) and hydrindantin (0.6 g l-1) were dissolved in the mobile phase to effect post-column derivatization of the amines without need for an extra reagent pump. Detection was by using a PTFE knitted-tube reactor at 145°C and measuring the absorbance at 546 nm. Recovery of amines from cheese was 85 to 105%. The detection limit was 2 mg kg-1 in cheese and the response was rectilinear for 0.1 to 4 µg of amine injected. Detection limits for amines in sauerkraut and wine were 0.8 and 0.3 mg kg-1, respectively.
Amines, biogenic HPLC Spectrophotometry Heated reaction Open tubular reactor Post-column derivatization Knotted reactor

"Post-column Derivatization Of Carbohydrates With Ethanolamine - Boric Acid Prior To Their Detection By High Performance Liquid Chromatography"
J. Chromatogr. A 1992 Volume 607, Issue 2 Pages 191-198
M. J. Del Nozal*, J. L. Bernal, F. J. Gomez, A. Antolin and L. Toribio

Abstract: Concentrated wine samples were subjected to HPLC on a column (50 cm x 3 mm) of Aminex A-25, operated at 69°C, with a mobile phase (1 mL min-1) of 0.4 M borate buffer (pH 9.35). The eluate was hydrolyzed by mixing with aqueous 1.6 M p-toluenesulfonic acid and the mixture was passed through a PTFE tube (10 m x 0.3 mm) at 140°C before merging with the fluorogenic reagent (an aqueous solution containing 20% ethanolamine and 20% H3BO3). The mixture was passed through a PTFE capillary (30 m x 0.3 mm) which was immersed in a reaction bath filled with glycerine at 140°C and then in a water bath at 20°C to cool the mixture. The fluorescence of the cooled mixture was measured at 445 nm (excitation at 400 nm). Melibiose was used as internal standard. Detection limits and calibration ranges for 11 carbohydrates are tabulated.
Carbohydrates HPLC Fluorescence Post-column derivatization Heated reaction Internal standard

"Direct Determination Of Biogenic Amines In Wine By Integrating Continuous-flow Clean-up And Capillary Electrophoresis With Indirect UV Detection"
J. Chromatogr. A 1998 Volume 803, Issue 1-2 Pages 249-260
Lourdes Arce, AngelR&iacute;os and Miguel Valc&aacute;rcel*

Abstract: A flow injection manifold for automating the determination of biogenic amines in wine using capillary electrophoresis (CE) with indirect UV detection was developed. The ensuing method involves clean-up and solid phase extraction (SPE) of the target analytes in the sample. Various treatments involving different SPE minicolumns were tested and compared. The C18 minicolumn was chosen to concentrate the amines following addition of ammonium chloride and ammonium hydroxide as buffer to neutralize them. Addns. of amine standards were used to determine recoveries. Biogenic amines can be separated and detected after SPE with limits of detection in the range 0.05-0.1 µg mL-1 by using 4 mM copper(II) sulfate, formic acid and 18-crown-6 as running buffer. All the amines studied are eluted within 15 min under the optimum conditions established. The overall process was successfully used to identify biogenic amines in various types of wine from different Spanish regions.
Amines, biogenic Electrophoresis Spectrophotometry Indirect Optimization Buffer

"Amperometric Substrate Determination In Flow Injection Systems With Polypyrrole - Enzyme Electrodes"
Sens. Actuat. B 1991 Volume 4, Issue 1 Pages 41-49
Wolfgang Schuhmann

Abstract: The polypyrrole films were prepared as previously described (Ibid, 1990, 1, 537) then glucose oxidase was covalently immobilized onto the electrode by immersing the electrode into a solution of the enzyme with activated carboxylic side chains and in the presence of glucose to block the active sites. After rinsing with 1 M KCl, the immobilized enzyme was crosslinked with 2% glutardialdehyde for 10 min to improve stability. The glucose oxidase electrode and the non-enzyme electrode were mounted in the flow-through cell of a flow injection system (described) and a potential of 600 mV vs. SCE was applied. The apparatus was applied to the determination of glucose in the presence of co-oxidizable compounds in fruit juice and wines. Due to the size-exclusion properties of polypyrrole, the thicknesses of the conducting polymer layers at both electrodes had to be equal to allow interfering compounds to be discriminated. Polypyrrole - glucose oxidase electrodes with the enzyme covalently bound to the outer surface of the functionalized polymetric network (prep. described) are used together with a similarly prepared non-enzyme electrode to determine glucose in the presence of co-oxidizable compounds in fruit juices and wines. Due to the size-exclusion properties of polypyrrole, the thicknesses of the conducting polymer layers at both electrodes have to be equal to allow interfering compounds to be discriminated. Polypyrrole - glucose oxidase electrodes and polypyrrole - albumin electrodes with a polymer thickness of 750 mC cm-2 are used with a flow injection system with an electrochemical cell (details given). The rectilinear range of the calibration graph and the detection limit are dependent on the flux of the carrier stream, and both peak height and peak width decrease significantly with its velocity. At a carrier flux of 36 mL h-1, the peak width at half peak height for 10 mM glucose was 25 s, allowing 60 analyzes per h. Reliability of results and throughput of samples compares well with that of standard photometric procedures.
Glucose Amperometry Electrode Immobilized enzyme Interferences Peak width

"Continuous-flow Determination Of Aqueous Sulfur By Atmospheric-pressure Helium Microwave-induced Plasma Atomic-emission Spectrometry With Gas-phase Sample Introduction"
Spectrochim. Acta B 1995 Volume 50, Issue 4-7 Pages 393-403
Taketoshi Nakahara*, Toshio Mori, Satoru Morimoto

Abstract: The borosilicate-glass gas-liquid separator described previously (J. Anal. Atomic Spectrom., 1992, 7, 211) was used with a Tokyo Rikakikai MP-3 microtube peristaltic pump, a laboratory-constructed Beenakker-type water-cooled TM010 microwave cavity and a N2-purgeable Ebert-type plane-grating far-UV monochromator (cf. Bunko Kenkyu, 1989, 38, 205). The sample solution stream (containing sulfide or sulfite) merged with a stream of 1 M HCl, the evolved H2S or SO2 was swept from the gas-liquid separator to the microwave-induced plasma by a stream of He carrier/plasma gas and the emission intensity at 180.73 nm was integrated over 10 s in triplicate. The detection limits for H2S and SO2 introduction were 0.13 and 1.28 ng/ml of S and the background equivalent concentrations were 20.9 and 62.2 ng/ml of S, respectively, and the calibration graphs were linear over approximately four decades. The RSD (n = 10) at 10 and 100 ng/ml of S with H2S introduction and at 40 and 400 ng/ml of S with SO2 introduction were 3.21, 1.13, 3.00 and 1.42%, respectively. The method was applied to determine sulfide in waste water and sulfite in wine.
Sulfide Sulfite Sulfur Spectrophotometry Volatile generation Volatile generation

"Determination Of Total Aliphatic Amines In Alcoholic Drink By Online Liquid-liquid Extraction/flow Injection Analysis"
Anal. Sci. 1988 Volume 4, Issue 5 Pages 537-538

Abstract: Sample solution (5 µL) was injected into the carrier solution (10 mM NaOH; 0.4 mL min-1) which was then mixed with reagent solution (Na 1,2-naphthoquinone-4-sulfonate; 0.4 mL min-1). The mixture passed to the reaction coil, which was immersed in a water-bath at 60°C, and, after mixing with segmenting extractant (CHCl3; 0.3 mL min-1), the mixture passed to an extraction coil and thence to a membrane phase separator. The derivatives in the organic phase were detected at 460 nm. The calibration graph for ethylamine was rectilinear from 1.3 to 132 ppm, and the detection limit was 0.5 ppm. The coefficient of variation (n = 10) for 6.6 ppm of ethylamine and 10.4 ppm of propylamine were 2.6 and 1.7%, respectively. The method was applied to determine amines in beer and wine.
Amines, aliphatic Ethylamine Propylamine Spectrophotometry Sample preparation Extraction Heated reaction Organic phase detection Phase separator

"Potentiometric Determination Of Ethanol In Alcoholic Beverages Using A Flow Injection Analysis System Equipped With A Gas Diffusion Unit With A Microporous Poly(tetrafluoriethylene) Membrane"
Anal. Sci. 1990 Volume 6, Issue 4 Pages 541-546

Abstract: The method involves the oxidation with K2Cr2O7 of ethanol permeating through a porous membrane, the reduction of unconsumed Cr2O72- with Fe2+ in a flow injection system, and the determination of the Fe3+ produced with a redox electrode. A diagram is presented of the flow injection manifold equipped with a gas diffusion separation unit. Results agreed with those obtained by a specific gravity method and by GC. The method is useful for application to alcoholic beverages owing to its high selectivity, high throughput, low cost and simplicity of operation.
Ethanol Potentiometry GC Gas diffusion Microporous membrane Redox Selectivity Heated reaction

"Microbial Sensor For Estimating Organic-acids In Wine"
Anal. Sci. 1995 Volume 11, Issue 6 Pages 941-945

Abstract: A microbial sensor based on an oxygen electrode and the microorganism Pseudomonas putida was developed in order to determine fixed acids, such as L-malic acid, succinic acid and L-lactic acid, in wine. The carbon source used in cultivating the microorganism affected the selectivity of the sensor to a great extent. When L-lactic acid was used as the carbon source, the microbial sensor gave a selective response for L-lactic acid. determining L-lactic acid was constructed and applied to commercially available wine samples. The obtained result was a flow injection analysis system for determining L-lactic acid was constructed and applied to commercially available wine samples. The obtained result was comparable to that obtained by the F-kit method. On the other hand, the microbial sensor showed a response for L-malic acid, L-lactic acid, succinic acid and ethanol present in wine when meso-tartaric acid was used in the cultivation. The addition of L-lactic acid (0.05 mM) and ethanol (0.01%) into the carrier solution suppressed the response for L-lactic acid and ethanol, and under the conditions the microbial sensor was thus selective for L-malic acid and succinic acid. The sensor responses for wine samples (n = 6) were linearly related to the sum of the L-malic acid and succinic acid concentrations determined by HPLC with a correlation coefficient of 0.969. (12 references)
Acids, organic l-Lactic acid l-Malic acid Succinic acid Electrode Sensor Immobilized cell Method comparison Interferences

"Flow Injection Sequential Speciation Of Free And Total Potassium In Fortified Wines"
Anal. Sci. 1996 Volume 12, Issue 6 Pages 887-891
A. O. S. S. RANGEL and I. V. TOTH

Abstract: A schematic is given of the FIA manifold. Wine was injected into the water carrier stream (1.7 ml/min) and merged with the ionic strength adjustor (0.75 M NaCl in 15 µM-KCl; 4.2 ml/min). Mixing occurred in a 100 cm coiled tube and the res The stream leaving the electrode system was merged with a water diluting stream (22 ml/min) and mixed in a 60 cm coiled tube. The sample plug flowed through to the flame AAS system for measurement of total K. The calibration graph was linear from 300-2000 mg/l of K. The RSD were The results compared well with those obtained by traditional methods using the same detection systems.
Potassium Spectrophotometry Speciation Ionic strength

"Comparison Of A Piezoelectric Impedance Sensor-based Flow Injection System And A N,N,N',N'-tetrakis-2-hydroxylethyl Ethylenediamine-coated Quartz Crystal Microbalance For Determination Of CO2 In Wine And Beer"
Anal. Sci. 1998 Volume 14, Issue 3 Pages 553-558
Xiao-Li SU), Hu-Wei TAN), Wei-Feng LI), Wan-Zhi WEI) and Shou-Zhuo YA

Abstract: A novel FIA system for CO2 was constructed and compared with a N,N,N',N'-tetrakis-2-hydroxylethyl ethylenediamine(THEED)-coated quartz crystal microbalance (QCM) for the determination of CO2 in wine and beer samples. This FIA method is based on the use of a gas-permeable membrane to sep. CO2 from a carrier stream of 0.5 mol/l phosphate buffer (pH 6.0) into a recipient stream of 10 mmol/l tris(hydroxymethylamino)methane (Tris) containing 1.0 mmol/l KCl and a piezoelec. impedance sensor to follow the conductance change occurring in the acceptor solution Although the results for real samples obtained by the FIA, the QCM and the conventional titrimetric methods agree well with each other, the FIA method offers the best precision. The FIA method is also characterized by its high throughout, promising sensitivity, excellent selectivity, low cost and easy manipulation, etc. The influence of some experimental parameters on the FIA's performance is discussed in detail.
Carbon dioxide Piezoelectric crystal Microbalance Sensor Conductometry Method comparison Optimization

"Spectrophotometric Flow Injection Determination Of Ethanol In Distilled Spirits And Wines Involving Permeation Through A Silicon Tubular Membrane"
Anal. Sci. 1998 Volume 14, Issue 5 Pages 1005-1008
Ivanildo L. MATTOS, Raquel P. SARTINI, Elias A. G. ZAGATTO, Boaventura F. REIS and Maria Fernanda GIN&Eacute;

Abstract: A concentric tubing reactor comprising an inner silicone tube and an outer polyethylene tube was assembled in a manifold for flow injection determination of ethanol in beverages. The number of potential interferents was restricted by mol. size, and permeation and chemical reaction are allowed to occur along the entire chemical path. For a typical sample with an ethanol content of 40.3%, the relative standard deviation (n=7) was 3.7%.
Ethanol Spectrophotometry Silicone membrane Permeation Tubular membrane Interferences

"Automated Determination Of The Total Polyphenol Index In White Wines By Flow Injection"
Afinidad 1986 Volume 43, Issue 406 Pages 530-536
Buitrago, J.;Cela, R.;Perez Bustamante, J.A.

Abstract: The method is a flow injection adaptation of that of Jerumanis (Bull. Assoc. R. Anc. Etud. Brass. Univ. Louvain, 1973, 69, 1), and involves reaction of the polyphenols with ammoniacal Fe(III) citrate to form a colored complex that absorbs at 525 nm. A modified univariant simplex optimization method was used to establish the best conditions. Gallic acid is the preferred calibration standard. The optimized method has a sample throughput of 200 h-1 and affords reproducibility of ±3.4%. In the analysis of six samples (mean polyphenolic index 96 to 139 ppm), the coefficient of variation was 4.71% (n = 7); results were lower than those obtained by the conventional version of the method.
Gallic acid Polyphenol index Spectrophotometry Simplex Optimization

"Analysis Of Pentoses In Dry Wine By High Performance Liquid Chromatography With Post-column Derivatization"
Am. J. Enol. Vitic. 1986 Volume 37, Issue 4 Pages 269-274
Bruce D. Franta, Leonard R. Mattick, and John W. Sherbon

Abstract: Wine samples were adjusted to pH 8 to 9 with concentrated aqueous NH3 and diluted with water before separation of the pentoses on an HPX-87P lead cation-exchange column (30 cm x 7.8 mm), at 70°C, fitted with an Aminex HPX-87C carbohydrate pre-column. Post-column derivatization with tetrazolium blue(I) was achieved with a reagent solution containing 80% ethanol - 0.01 M NaOH - 0.1% I at 1.1 mL min-1 and a 1.8-m reaction coil at 85°; detection was at 520 nm. The rectilinear ranges for xylose, arabinose, ribose, glucose and rhamnose extended up to 2.4 µg (that for fructose up to 1.2 µg), coefficient of variation were ~2% and detection limits were <0.3 µg. The method was only applicable to dry wines as large glucose concentration. (e.g., in sweet wines) affected the determination of xylose.
Pentoses Xylose Arabinose Ribose Glucose Rhamnose HPLC Spectrophotometry Heated reaction Post-column derivatization

"Determination Of Metallic Cations In Wines By Flow Injection Analysis"
Am. J. Enol. Vitic. 1990 Volume 41, Issue 4 Pages 284-288
Jos&eacute; L. F. C. Lima and Ant&oacute;nio O. S. S. Rangel

Abstract: Four flow-injection manifolds were developed aiming to automate the determination of metallic cations (Na, K, Ca, Mg, Fe, Mn, Zn, and Cu) in wines using atomic absorption (AAS) and flame emission (FES) spectrometry as detection processes. Good agreement was obtained between the results of FIA methods and by the reference methods, in which samples are prepared in a discrete manner and then introduced into the detection system. The FIA methods developed present good quality results (relative standard deviation between 0.57% and 1.4%) with high sampling rates (180 to 360 samples per hour) and a low reagent consumption.

"Enzymatic Determination Of L(-)malic And L(+)lactic Acids In Wine By Flow Injection Analysis"
Am. J. Enol. Vitic. 1992 Volume 43, Issue 1 Pages 58-62
Jos&Eacute; L. F. C. Lima and Ant&oacute;nio O. S. S. Rangel

Abstract: The enzymatic determination of L-(-)-malic and L(+)lactic acids in several types of wines by flow injection analysis (FIA) with spectrophotometric detection is described. This flow injection system, which incorporates a dialysis unit for adjusting the composition of the injected solutions to the requirements of the measuring system, enables determinations of these two organic acids without the need for any prior treatment of the wine samples, with a concentration. interval of between 0.02 and 4 g/L, and a sampling rate of approximately 20 determinations per h. The results obtained with this FIA method for various types of Portuguese wines are in good agreement with those of the batch method which uses the same enzymatic technique and are quite precise as they present a coefficient of variation below 2.5%.
l-Malic acid l-Lactic acid Spectrophotometry Dialysis Method comparison Enzyme

"Potential Of Flow Injection Methodology For Beverage Analysis"
Am. J. Enol. Vitic. 1992 Volume 43, Issue 1 Pages 93-100
M. D. Luque De Castro and J. A. Garc&iacute;a-Mesa

Abstract: A literature review of the use of flow injection analysis for the analysis of beverages (particularly wines) is presented. The different possibilities of carrying out individual and multiple determinations (whether simultaneous or sequential) with or without the aid of continuous on- line separation are critically discussed.
Review Method comparison Sequential injection Simultaneous analysis

"Automated Determination Of Total Acidity In Wines By Flow Injection Analysis"
Am. J. Enol. Vitic. 1993 Volume 44, Issue 1 Pages 118-120
Miguel Peris-Tortajada, A. Maquieira, and R. Puchades

Abstract: Two automatic flow injection methods for the determination of total acidity in wine based on an acid-base titration are proposed. Their usefulness was tested by applying them to different wine samples (red, rosé, and white). The results obtained agree with those provided by a batch standard method. The features of both methods make them suitable for adaptation to enological laboratories with a view to continuous or irregular monitoring.
Acidity Automation

"A New Approach To Dialysis In Sequential Injection Systems: Spectrophotometric Determination Of L(+)-lactate In Wines"
Am. J. Enol. Vitic. 1997 Volume 48, Issue 4 Pages 428-432
Alberto N. Ara&uacute;jo, Jos&eacute; L.F.C. Lima, M. L&uacute;cia M.F.S. Saraiva, and Elias A.G. Zagatto

Abstract: A sequential injection analysis (SIA) system for the spectrophotometric determination of L(+)-lactate using lactate oxidase/peroxidase was developed and applied to wine analysis. It incorporates a dialysis unit between the pump and the selecting valve to provide online dilution and interference minimization of the sample matrix. A volume of 100 µL of carrier solution trapped in one channel of the dialysis unit, acts as donor and acceptor solution. With an assay cycle of 262 seconds, the system allows a sample throughput of 14 samples per hour and yields precise results (rsd < 2%). Peroxidase (0.0512 IU) and 0.0384 IU of lactate oxidase promote the conversion of L(+)-lactate in 160 µL of sample, allowing its determination within the 0.25 to 2.5 g/L range. A detection limit of 0.074 g/L was calculated. Results are in good agreement with those obtained with the conventional method (Boehringer UV-Kit).
l-Lactate Spectrophotometry Sequential injection Interferences Dilution Method comparison Dialysis

"Construction And Evaluation Of A Crystalline Silver Double-membrane Tubular Potentiometric Detector For Flow Injection Analysis. Application To Chloride Determination In Wine"
Analusis 1998 Volume 26, Issue 4 Pages 182-186
C.M.C.M. Couto, J.L.F.C. Lima and M.C.B.S.M. Montenegro

Abstract: This paper describes the construction and assessment of the operating characteristics and analytical usefulness of a homogeneous crystalline silver double membrane tubular electrode with increased sensitivity. The electrodes allowed Ag(I) determinations in the 3 x 10^-5 - 1 x 10^-1 M range with a calibration slope of 114 mV dec-1 and with good reproducibility (0.6 mV). The development and application of a flow injection analysis system manifold for chloride determinations in wine samples, in a wide concentration range (10-800 mg L-1), with a titrant consumption of 90 µg determination-1 is also described. The results obtained from the analysis of 12 wine samples showed good agreement between the proposed method and the reference one, accomplishing rates of 90-200 h-1.
Chloride Potentiometry Electrode Electrode Indirect Method comparison

"Measurement Of L-malate Using Immobilized Enzyme Reactors Comparison Of Results Obtained With Four Different Enzymatic Systems"
Biosci. Biotechnol. Biochem. 1996 Volume 60, Issue 5 Pages 847-851

Abstract: For the measurement of malate by an enzyme sensor, we did a comparative study using malate dehydrogenase (MDH) alone, MDH and glutamate oxaloacetate transaminase (GOT) together, a malic enzyme (ME) that requires NADP as a cofactor, and MDH and NADH oxidase together, With respect to the response of each reactor to 0.5 mM L-malate, the systems using ME alone and MDH plus NADH oxidase gave high values, The ranges of measurements were 0.05-1.00 mM (MDH alone), 0.01-0.05 mM (MDH plus GOT), 0.01-0.50 mM (ME alone) and 0.02-1.00 mM (MDH plus NADH oxidase), In the system with MDH alone, however, reducing sugars in the sample interfered with measurements and it was impossible to use this system for practical analysis of fruit samples, By contrast, the systems using ME alone or MDH plus NADH oxidase were unaffected by the presence of reducing sugars and were suitable for analysis of samples, Thus, the MDH-NADH oxidase system is recommended for practical analyzes of samples.
l-Malate Amperometry Enzyme Interferences Immobilized enzyme

"Enzyme Electrode For Online Determination Of Ethanol And Methanol"
Biotechnol. Bioeng. 1987 Volume 30, Issue 9 Pages 1001-1005
Hafedh Belghith, Jean-Louis Romette *, Daniel Thomas

Abstract: The alcohol oxidase was isolated from a strain of Hansenula polymorpha yeast, and immobilized in a gelatin matrix. The electrode formed from this membrane was used in a continuous-flow system for the determination of 0.5 to 15 mM ethanol or 10 to 300 mM methanol. Time for analysis, including data processing, was <2 min and the electrode response was stable for ~500 determinations. The method was applied in analysis of, e.g., wine and beer, and the results agreed with those of standard methods.
Ethanol Methanol Electrode Computer Immobilized enzyme Method comparison Standard method

"Determination Of Ethanol Based On Oxygen Consumption With An Enzyme Sensor Using Vitamin K3 [menaphthone] As A Mediator"
Bunseki Kagaku 1989 Volume 38, Issue 11 Pages T165-T169
Ukeda, H.;Matsubara, M.;Matsumoto, K.;Osajima, Y.

Abstract: Ethanol was determined in wine by flow injection analysis. Sample was injected into a carrier stream of 0.05 M phosphate buffer (pH 8.0) and pumped through a reactor packed with Sepharose 4B, on which alcohol dehydrogenase (I) and dihydrolipoamide dehydrogenase were co-immobilized, to a flow-through cell equipped with a Clark oxygen electrode. Menaphthone was used for regeneration of NAD+ from the NADH formed in the reaction of I. A calibration graph of current vs. concentration. was rectilinear from 0.4 to 2 mM ethanol and the detection limit was 50 µM. The coefficient of variation was 1.1% (n = 5). The sampling frequency was 15 samples h-1. Results agreed well with those obtained by the F-kit method.
Ethanol Electrode Sensor Buffer Sepharose beads Reactor Immobilized enzyme Method comparison

"Simultaneous Determination Of L-malate And Ethanol In Wine By A Sensor Based On Oxygen Consumption Including Parallel Configuration Of Enzyme Columns"
Bunseki Kagaku 1990 Volume 39, Issue 11 Pages 723-727
Ukeda, H.;Nakada, Y.;Matsumoto, K.;Osajima, Y.

Abstract: A flow injection analysis system (illustrated) was developed consisting of two parallel enzyme reactors with a single O electrode. L-Malate (I) was determined by injecting sample solution into a carrier stream of 0.05 M pyrophosphate buffer (pH 9.0) saturated with vitamin K3 (0.5 mL min-1). The stream was mixed with NAD solution and the mixture was passed through a malate dehydrogenase - diaphorase enzyme reactor. Ethanol (II) was determined by injecting sample solution into a stream of 0.05 M phosphate buffer (pH 8.0; 1.0 mL min-1) and the mixture was passed through an alcohol oxidase enzyme reactor. Sample solution was injected simultaneously into both reactors. Calibration graphs were rectilinear from 90 to 900 µM I and from 18 to 50 mM II. The method was applied in the simultaneous determination of I and II in wine. Results were compared with those by HPLC and the F-kit method.
l-Malate Ethanol Electrode HPLC Sensor Enzyme Column Buffer pH Simultaneous analysis

"Flow Injection Determination Of Sugars In Foods By Use Of A Porphinatotitanium(IV) Reagent"
Bunseki Kagaku 1995 Volume 44, Issue 5 Pages 355-362
Yokoi, Y.;Matsubara, C.;Takamura, K.

Abstract: Sample solution (20 µL) was injected into a stream (0.4 ml/min) of 0.05 M phosphate buffer/1 mM MgCl2 (pH 6.6). To determine glucose, the stream passed directly to a column of glucose oxidase, merged with a stream (0.4 ml/min) of 30 µM-oxo-[5,10,15,20-tetra-(4-pyridyl)porphinato]titanium(IV), and then passed through a mixing coil (15 m x 0.5 mm i.d.) maintained at 75°C before absorbance measurement at 450 nm. To determine maltose, lactose or sucrose, the stream after injection of the sample passed first through a column of glucose oxidase/catalase, then through a column of α-glucosidase, β-galactosidase, or β-fructofuranosidase/aldose 1-epimerase, respectively, and then through a column of glucose oxidase before merging with the reagent stream. Calibration graphs for glucose and for maltose, lactose or sucrose were linear over the ranges 0.5-500 µM and 1-1000 µM, respectively, and the respective RSD (n = 10) at 100 µM-glucose, -maltose, -lactose or -sucrose were 0.74, 0.84, 0.49 and 0.75%. The four carbohydrates were determined in milk, soft beverages and wine.
Glucose Maltose Lactose Sucrose Spectrophotometry Immobilized enzyme Heated reaction

"Trace Analysis Of Sugars By HPLC And Post-column Derivatization"
Chromatographia 1987 Volume 23, Issue 9 Pages 657-662
H. Engelhardt and P. Ohs

Abstract: Sugars, e.g., arabinose, glucose, fructose (each 80 ng), raffinose and sucrose (each 160 ng), were separated on a column at 36°C containing the strongly basic anion-exchange resin HPIC-AS6 (Dionex) with 0.15 M NaOH as mobile phase (0.5 mL min-1). The eluate was treated with 0.2% thymol in concentrated H2SO4 in a specially designed reaction coil operated at >90°C. Detection was at 500 nm. Results are presented for 17 sugars. The method has been applied to the determination of fructose and glucose in wine with a high residual sugar content (after a 100-fold dilution) and to dry wine, for which a 'fingerprint' analysis illustrates a separation of several sugars. Sugar alcohols, acids and other wine constituents did not interfere.
Arabinose Glucose Fructose Raffinose Sucrose Sugars HPIC Spectrophotometry Heated reaction Interferences Post-column derivatization

"Applications Of Flow Injection Analysis In Enology"
Cienc. Tec. Vitivinic. 1990 Volume 9, Issue 1-2 Pages 95-113
Lima, J.L.F.C.;Rangel, A.O.S.S.

Abstract: A review with 27 references discussing the use in wine analysis of flow-injection techniques coupled with spectrophotometry, amperometry, enthalpimetry, atomic absorption spectrometry, flame emission spectrometry, and potentiometry. (SFS)
Spectrophotometry Amperometry Enthalpimetry Spectrophotometry Spectrophotometry Potentiometry Review

"Determination Of Tartaric Acid In Wine By Segmented Continuous-flow Analysis"
Cienc. Tec. Vitivinic. 1990 Volume 9, Issue 1-2 Pages 115-120
Curvelo Garcia, A.S.;Godinho, M.C.

Abstract: The colorimetric procedure of H. Rebelein (1972) for determination of L-(+)-tartaric acid in wine was adapted to segmented continuous-flow anal. Rates of sample throughput were 40/h. Linearity of response was best in the range 3-8 g/L; sep. calibration was required for lower concentrations The relative standard deviation was <3.5%, and recoveries were 94.0-106.3%. (SFS)
Tartaric acid Spectrophotometry Segmented flow

"Enhanced Automatic Flow Injection Determination Of The Total Polyphenol Index Of Wines Using The Folin-Ciocalteu Reagent"
Colloq. Inst. Natl. Rech. Agron. 1995 Volume 69, Issue 1 Pages 461-462
Mercedes Celeste, Consuelo Tom&aacute;s, Andreu Cladera, Jos&eacute; Manuel Estela, Victor Cerd&agrave;

Abstract: A new automated FIA method for the determination of the total polyphenol index in wines on the Folin-Ciocalteu reaction in 0.5 mol L-1 NaOH is proposed. The method is highly tolerant to the most common interferences with its batch counterpart (e.g. sulfur dioxide, reducing sugars and ascorbic acid): it tolerates upto 400 mg L-1 sulfur dioxide, 50 mg L-1 ascorbic acid and 40 g L-1 glucose with errors less than 10% and is subject to a lesser synergistic effect from sulfur dioxide, reducing sugars, and o-hydroxyphenols.
Polyphenol index Spectrophotometry Interferences

"Continuous-flow Automation Of The Enzymic Determination Of Malic Acid In Wines"
Connaiss. Vigne Vin 1980 Volume 14, Issue 4 Pages 207-217

Abstract: Malic acid [6915-15-7] in wine was determined by a continuous enzymatic process that produced NADH. The NADH was used to reduce 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (I) [298-93-1] to the corresponding formazan derivative (II) [57360-69-7]. The transfer of H from NADH to I was accomplished with Meldola Blue. The amt. of II formed was determined by spectrometry at 570 nm.
l-Malic acid Spectrophotometry Enzyme

"Automation Of Continuous-flow Enzymic Determination Of Acetic Acid In Wine"
Connaiss. Vigne Vin 1985 Volume 19, Issue 3 Pages 161-169

Abstract: The sample was mixed with triethanolamine solution (pH 8.4), malate, MgCl2, ATP, coenzyme A, NAD+ and acetyl-CoA synthetase before being incubated at 37°C with malate dehydrogenase and citrate synthase. A solution of Meldola blue (C. I. Basic Blue 6) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was added and, after 5 min, the absorbance was measured at 570 nm. The coefficient of variation was <5%.
Acetic acid Spectrophotometry

"Influence Of Malic Acid Concentration On The Determination Of Tartaric Acid In Musts By Continuous-flow Colorimetry With Metavanadate"
Connaiss. Vigne Vin 1985 Volume 19, Issue 4 Pages 249-259

Abstract: The cited continuous-flow technique for determining tartaric acid, based on the method of Blouin and Vidal (Rev. Fr. Oenol., 1978, 70, 39), gave values ~20% lower than those from the method of Rebelein (Dtsch. Lebensm.-Rundsch., 1961, 2, 36). These errors are due to interference by other organic acids present in musts, especially malic acid, which is eliminated in the Rebelein method. Use of a correction factor is proposed for the continuous-flow method, to allow for the relatively large malic acid levels in musts.
Tartaric acid Spectrophotometry Interferences

"Determination Of Total Phosphorus And Inorganic Phosphorus In Wines By Flow Injection Analysis"
Connaiss. Vigne Vin 1990 Volume 24, Issue 2 Pages 49-61

Abstract: To determine inorganic P, wine was injected into a aqueous carrier stream which merged with a reagent stream of (NH4)2MoO4- SnCl2 (details given). After passing through a reaction coil, the absorbance of the mixture was measured at 710 nm. To determine total P, wine was evaporated to near-dryness on a water-bath and the residue was treated with concentrated HNO3 for 1 h, ignited at 650°C then dissolved in 3 M HCl. The resulting solution was then analyzed as above. The sample throughput for the determination of total P was 120 h-1 with a coefficient of variation of 2%. Inorganic P could be determined from 9 to 1000 mg mL-1 at a sample rate of 60 h-1 with a coefficient of variation of 2%.

"Simultaneous Determination Of Calcium And Potassium, Magnesium And Sodium, And Potassium And Sodium In Wine Using Flow Injection Analysis Manifolds With A Dialysis Unit"
Connaiss. Vigne Vin 1990 Volume 24, Issue 4 Pages 167-176

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

"Ion-chromatographic Analysis Of Alkali- And Alkaline-earth-metal Contents In Wine"
Dtsch. Lebensm. Rundsch. 1990 Volume 86, Issue 6 Pages 178-182

Abstract: To determine Na or K, the sample was diluted 1:40 or 1:500, respectively (for Na, the sample was boiled with 30% H2O2 before dilution) and analyzed on a Dionex HPIC-CS1 - HPIC-CG1 column system with 5 mM HCl as mobile phase (2 mL min-1) and use of a hollow-fiber membrane suppressor. To determine Ca or Mg, the sample was diluted 1:20 to 1:50 and analyzed on a Partisil SCX (10 µm) column with 2.5 mM oxalic acid - 2 mM ethylenediamine (pH adjusted to 3.5 with HCl) as mobile phase (1 mL min-1) and photometric detection at 490 nm after post-column derivatization with Zn - EDTA - 4-(2-pyridylazo)resorcinol at pH 11.0. A determination by either method takes ~15 min. The simultaneous determination of all four cations can be achieved in 40 min on a LiChrospher RP-18 column with 2 mM hexylsuccinic acid - 1 mM oxalic acid as mobile phase and conductometric detection. The concentration. of Na, K, Ca and Mg found in wine were 3 to 20, 800 to 1500, 60 to 140 and 70 to 100 mg l-1, respectively.
Metals, alkaline earth Metals, alkali Magnesium Sodium Potassium Calcium HPIC Spectrophotometry Column Membrane Post-column derivatization EDTA pH

"Biosensors In Automated Analysis Systems. 1. Determination Of Ethanol In Beer And Wine By Flow-diffusion Analysis And Amperometric Detection"
Dtsch. Lebensm. Rundsch. 1996 Volume 92, Issue 1 Pages 1-4

Abstract: The flow diffusion system employed (schematic given) included a thermostatted diffusion cell with a hydrophobic gas diffusion membrane, an enzyme reactor, and a thick-layer Pt electrode in a wall-jet flow cell. The ethanol was converted enzymatically to acetaldehyde and H2O2, and the H2O2 detected electrochemically at the Pt electrode at 700 mV. The enzyme was alcohol oxidase immobilized by the glutaraldehyde method on CPG 10 (controlled pore glass). Twenty alcohol-free beers, 16 beers and 13 wines were examined. The correlation between this method and the standard methods was very good (correlation coefficient of 0.9992). Thirty samples per hour could be analyzed and the flow analysis system had a linear range up to 15% v/v.
Ethanol Sensor Electrode Electrode Amperometry Immobilized enzyme Controlled pore glass Method comparison Gas diffusion Dialysis Standard method

"Flow Injection Analysis Of Carbonate, Sulfite And Acetate In Food"
Dtsch. Lebensm. Rundsch. 1996 Volume 92, Issue 10 Pages 323-328

Abstract: For carbonate, drinking water was analyzed directly, mineral water was ultrasonically degassed, and orange drink was ultrasonically degassed and diluted with water (1:2). Sulfite in white wine was determined directly. For acetate, pickled gherkins and pepperoni were extracted with water. Solutions were injected into a water carrier, the stream was mixed with 5 mM H3PO4 to release the acidic gas or vapor, and this diffused into bromocresol violet/bromothymol blue/cresol red/KCl indicator in carbonate buffer (pH 8.3) for photometric detection at 430 nm or into dilute NaOH of pH 9.5 for potentiometric detection, or into iodine/KI/starch solution of pH 9.5 for photometric detection of sulfite at 620 nm. Alternatively, for acetate, the sample solution was adjusted to pH 8.4 with NaOH and injected into FeCl3 for photometric determination of the Fe-acetate complex at 405 nm. Conditions were optimized (details given), and means of overcoming interference are given. The iodimetric method was preferred for sulfite. Results agreed well with those of standard methods.
Sulfite Carbonate Acetate ion Spectrophotometry Potentiometry Interferences Standard method Method comparison Optimization

"Study On A Coulometric Detector Based On A Porous Carbon Felt As A Working Electrode For Flow Injection Analysis And Its Application"
Fenxi Huaxue 1995 Volume 23, Issue 3 Pages 292-296
Chen, G.N.

Abstract: Construction of the cited detector and its incorporation into a flow injection analyzer. is described. Ascorbic acid, hydroquinone, gallic acid and SO2 were used as model analytes; the detection limits were 20, 10 and 30 nM, and 8 µM, respectively. Other properties were also investigated (e.g., linear range, selectivity). The detector was used to replace the 'clean-up' cell in the dual-detector flow injection analysis system for the determination of SO2 in wine; optimum conditions were 1 mM H2SO4 as carrier (0.4 ml/min) and a detector working potential at 0.41 V vs. an ion-couple electrode. The results were compared with those obtained by the aspiration-oxidation method.
Ascorbic acid Gallic acid Hydroquinone Sulfur dioxide Coulometry Electrode Method comparison

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

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

"Multicomponent Flow Injection Analysis - Determination Of Potassium And Calcium In Wine"
Food Chem. 1990 Volume 38, Issue 2 Pages 105-112
L. Ilcheva, R. Yanakiev, V. Vasileva and N. Ibekwe

Abstract: Wine (50 to 100 µL) was injected into an aqueous carrier stream (1.0 mL min-1), and mixed with 0.1 M Na acetate buffer (1.0 mL min-1) in a coil (25 cm x 0.7 mm) for detection of K+ and Ca2+ in a PTFE cell with Radiometer ion-selective electrodes vs. a SCE. Nernstian response was obtained for 50 µM to 2 mM of each metal. Analysis time was 30 samples h-1. Results were within 4% of those obtained by established methods. A flow injection potentiometric method for simultaneous determination of potassium and calcium is suggested. The optimized double-channel flow system, in relation to component, speed of carrier solution, volume of the sample and length of the mixing tube, is characterized with high productivity (30-60 samples per hour) and simple technical equipment. The method is applied for analysis of wine. In this case, the reproducibility of results is lower than 2% while the accuracy, as compared with other methods, is not more than 5%. No preliminary treatment of the wine sample is required.
Calcium Potassium Electrode Potentiometry Optimization Buffer Multicomponent Method comparison

"Simultaneous Enzymic Determination Of L-(.minus.)-malic Acid And L-(+)-lactic Acid In Wine By Flow Injection Analysis"
Food Chem. 1991 Volume 42, Issue 2 Pages 167-182
R. Puchades, M. A. Herrero, A. Maquieira and J. Atienza

Abstract: Online dialyzed samples (80 µL) were injected into the carrier stream [0.05 M carbonate - bicarbonate buffer (pH 9.7) containing 1.5 mM NAD+ and 1 mM EDTA; flow rate 1 mL min-1], which then split into three. One channel (length 64 cm) contained a blank reactor, and the second and third channels (lengths 95 and 185 cm, respectively) contained open tubular glass column reactors (8 cm x 1.2 mm) respectively packed with L-malate dehydrogenase and L-lactate dehydrogenase covalently immobilized on alkylamine glass beads. The flows then converged before reaching the detector flow cell, where the fluorescence intensity of the NADH produced by the enzyme-catalyzed oxidation of L-(-)-malic and L-(+)-lactic acid (I and II, respectively) was measured at 450 nm (excitation at 340 nm). The different dimensions of the three channels provided different residence times, giving three peaks, the first being due to matrix fluorescence. The calibration graphs were rectilinear from 0.1 to 5 mM and from 0.05 to 3 mM for I and II, respectively. Tartaric acid, fructose and SO2 did not interfere. The method was applied to the analysis of 20 commercially available wines. The results agreed with those obtained by HPLC.
l-Lactic acid l-Malic acid Fluorescence Buffer Catalysis EDTA Glass beads Immobilized enzyme Interferences Reactor

"Determination Of Reducing Sugars By The Neocuproine Method Using Flow Injection Analysis"
Food Chem. 1992 Volume 43, Issue 1 Pages 65-69
Miguel Peris-Tortajada, Rosa Puchades and Angel Maquieira*

Abstract: A flow injection method was optimized for the cited determination. A 143 µL sample was injected into a stream of Cu(II) - neocuproine reagent (prep. described) at 1.15 mL min-1 and the mixture was passed through a dialysis unit and a reactor (100-cm long). The eluting stream was merged with 0.5 M NaOH, at 1.15 mL min-1, and passed through a reactor (200-cm long) at 65°C before the absorbance of the solution was measured at 460 nm. Recoveries are tabulated for three dialysis membranes. Recoveries of reducing sugars from wine and foods were ~100%.
Sugars, reducing Spectrophotometry Optimization Dialysis Membrane Heated reaction

"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 Electrode Potentiometry Titrations Well stirred mixing chamber Optimization Indirect

"Determination Of Calcium, Magnesium, Sodium And Potassium In Wines By FIA Using An Automatic Zone Sampling System"
Food Chem. 1996 Volume 55, Issue 4 Pages 397-402
Rui A. S. Lapa, Jos&eacute;L. F. C. Lima* and Jo&atilde;o L. M. Santos

Abstract: An automatic FIA unit based on the zone sampling technique is described. The sample was injected into a first carrier stream and dispersed on a dilution coil. By rotating the injection valve, a portion of the dispersed sample plug was introduced into a second carrier stream and directed towards the detector. A microcomputer was used as the control unit. Ca and Mg were determined by AAS whilst Na and K were determined by flame photometry. The results agreed well with those obtained by reference methods. RSD were 1.6% for Ca, 2.7% for Mg, 1.4% for Na and 3.2% for K.
Calcium Magnesium Potassium Sodium Spectrophotometry Spectrophotometry Zone sampling Method comparison Computer

"The Determination Of The Authenticity Of Wine From Its Trace Element Composition"
Food Chem. 1997 Volume 60, Issue 3 Pages 443-450
Malcolm J. Baxter, Helen M. Crews, M. John Dennis,*, Ian Goodall and Dorothy Anderson

Abstract: Multi-element analysis of 112 Spanish and English wines by inductively coupled plasma mass spectrometry (ICP-MS) was undertaken to ascertain whether or not this method could provide data for determining the region of origin of wine. Flow injection analysis proved superior to continuous nebulisation. Quality assurance of these measurements proved entirely satisfactory and was typical of that previously established for this technique. An intercomparison exercise with another expert laboratory showed satisfactory agreement. The data was examined using the statistical technique of discriminant analysis. This was able to unequivocally identify the region of origin of Spanish wines from three different regions. It was also possible to completely differentiate English and Spanish white wines. If red and rose wines were included in the Spanish set, the English and Spanish populations could be distinguished with 95% accuracy. This preliminary study has indicated the power which multi- element analysis can bring to determining the region of origin of wines. At present, no other technique has the ability to perform this categorisation.
Metals, trace Mass spectrometry Method comparison

"Determination Of Total Acidity In Wines And Fruit Juices By Flow Injection Analysis"
GBF Monogr. Ser. 1989 Volume 11, Issue 1 Pages 277-280
Flossdorf, Josef; Wansheng, Yang (SFS)

Abstract: Procedures developed by J. Ruzicka were used for flow-injection anal. of total acidity in beverages. Agreement with the standard method is better than ±2%. Up to 30 determinations per h are possible with each 100-150 µL sample volume (SFS)
Acidity, total

"Application Of A Flow Injection System In Wine Analysis"
J. Agric. Food Chem. 1991 Volume 39, Issue 5 Pages 909-910
Marta Kotorman, Maria L. Simon, and Bela Szajani

Abstract: A flow injection system with an immobilized lactate dehydrogenase enzyme reactor was constructed and characterized. The system was successfully used to determine the free lactic acid content of Hungarian red and white wines.

"Simultaneous Continuous-flow Analysis Of Free And Total Sulfur Dioxide In Wine"
J. Agric. Food Chem. 1992 Volume 40, Issue 8 Pages 1355-1357
Fernando Falcone and Kenneth C. Maxwell

Abstract: Continuous-flow analysis of the cited compounds was conducted on a TRAACS 800 flow analyzer.. The method was based on the formation of a colored compound from reaction of the analyte, formaldehyde and p-rosaniline. The sample was introduced into the autosampler and split with half going to channel 1 (free SO2) and the other half to channel 2 (total SO2). For the determination of total SO2 the sample was first made basic with NaOH to liberate the bound SO2. Both samples were then acidified with H2SO4 to convert all forms of free SO2 to gaseous SO2, a portion of which diffused across a gas-permeable membrane into a stream of 1% H2SO4. The stream was mixed with formaldehyde and reacted with p-rosaniline. The complex was measured at 550 nm. The continuous-flow analysis was comparable to the Ripper method. Recoveries from sulfite-spiked wine samples ranged from 62 to 104% with an average precision of 4.5%.
Sulfur dioxide Spectrophotometry Gas diffusion Sample splitting

"Determination Of Lead Contamination In Spanish Wines And Other Alcoholic Beverages By Flow Injection Atomic Absorption Spectrometry"
J. Agric. Food Chem. 1997 Volume 45, Issue 5 Pages 1812-1815
Concepcion M. Mena, Carmen Cabrera, M. Luisa Lorenzo, and M. Carmen Lopez

Abstract: Lead was determined directly in wine by flow injection hydride-generation AAS and in beer and cider with prior online microwave oven treatment. Other alcoholic beverages were first microwave digested with HNO3 at 120°C for 90 min. Lead hydride was generated in HNO3/H2O2 medium using NaBH4 and was carried by Ar to the atomization cell where it was heated by an acetylene-air flame (no details given of temperature). The Pb line at 217.0 nm was monitored. The detection limit was 10^-12 µg/l Pb and the RSD were 4-8% (n = 10). The concentrations of Pb in 70 wines and 64 other beverages are reported and discussed.
Lead Sample preparation Spectrophotometry Online digestion Microwave Volatile generation Volatile generation

"Determination Of Sulfur Dioxide In Wines And Beverages By Flow Injection Analysis With Reductive Amperometric Detection And Electrolytic Cleanup"
J. AOAC Int. 1993 Volume 76, Issue 6 Pages 1389-1393
Cardwell, T.J.;Cattrall, R.W.;Chen, G.N.;Scollary, G.R.;Hamilton, I.C.

Abstract: For the determination of free SO2, 2 mL of wine was mixed with 1 mL of 0.01 M H2SO4 and water to 10 ml; for total SO2, 1 mL of wine was mixed with 0.5 mL of 0.5 M NaOH and water to 10 mL. In each case, a portion of the resulting solution (10 µL) was injected into a carrier stream of 0.01 M H2SO4 of pH 1.47 at 0.8 ml/min and the mixture was passed to a dual electrode analytical cell for the elimination of interference by reduction vs. H+:H2 couple at -0.26 V before detection of the analyte at an amperometric electrode at -0.41 V vs. H+:H2. A diagram of flow manifold is given. The effect of 20 frequently occurring compounds in wines was investigated; only acetaldehyde, pyruvic acid and 2-oxoglutanic acid interfered significantly. The calibration graphs were linear up to 20 mg/l for free and total SO2 with RSD of 3% and 4%, respectively. The method was applied to 27 wines and 11 other beverages including fruit juices, wine coolers and ciders with a sample throughput of 30/h. A new flow injection method is described for the determination of sulfur dioxide in red and white wines and other beverages. A dual- electrode electrochemical detector eliminates interferences by reduction at an upstream coulometric electrode before reductive detection of sulfur dioxide at the amperometric electrode. The data for free and total sulfur dioxide in wines and other beverages agree well with those obtained by the standard aspiration-oxidation method.
Sulfur dioxide Amperometry Redox Interferences

"Semiautomatic Determination Of Furanic Aldehydes In Food And Pharmaceutical Samples By A Stopped-flow Injection Analysis Method"
J. AOAC Int. 1993 Volume 76, Issue 6 Pages 1255-1261
Espinosa Mansilla, A.;Munoz De La Pena, A.;Salinas, F.

Abstract: Sample solution was injected into a carrier stream of water which merged sequentially with a stream of 5 M HCl and a stream of 0.03 M 2-thiobarbituric acid. The procedure was carried out at 40°C and the reaction was monitored at 425 nm. A schematic diagram of the stopped-flow FIA system is presented. The method was used to determine 5-hydroxymethyl-2-furfuraldehyde (I) and furfural in honey, orange and grape juice, red wine and pharmaceuticals. The calibration graph was linear for 1.1-14.6 µg/ml of I and the detection limit was 0.47 µg/ml. The RSD for 5.6 µg/ml of I (n = 10) was 2.4%. Sample throughput was ~40/h; details are given of the manual and automatic steps of the procedure. A kinetic study of the reactions of 5-hydroxymethyl-2-furfuraldehyde and furfural with 2-thiobarbituric acid (TBA) by a stopped-flow flow injection analysis technique has been undertaken. A semiautomatic method for the analytical determination of these furanic aldehydes is proposed on the basis of reaction with TBA. The proposed stopped-flow method was successfully applied to several commercial pharmaceutical preparations and food samples. The procedure is faster than the earlier procedure for determination of these compounds in foods and pharmaceuticals.
Aldehydes, furanic Spectrophotometry Stopped-flow Kinetic

"Determination And Speciation Of Arsenic In Human Urine By Ion-exchange Chromatography - Flow Injection Analysis With Hydride Generation - Atomic Absorption Spectroscopy"
J. AOAC Int. 1994 Volume 77, Issue 2 Pages 441-445
Jimenez De Blas, O.;Vicente Gonzalez, S.;Seisdedos Rodriguez, R.;Hernandez Mendez, J.

Abstract: For the determination of total As in urine, the organic matter was oxidized by a mineralization procedure (Minoia et al., Med. Lavoro, 1978, 69, 681) before determination by FIA - hydride-generation AAS using a standard-additions method. Separation of metabolic forms of As was performed by cation-exchange on a column (20 m x 1 cm i.d.) of AG50W-X80 (H+ form; 100-200 mesh) washed with 0.5 M HCl. The urine sample was acidified with concentrated HCl before elution by gravity (~3 ml/min). The method was based on that previously described by Tam et al. (cf. Bull. Environ. Contam. Toxicol., 1979, 21, 371) and the fractions collected were analyzed for As species by FIA - hydride-generation AAS. The instrument used was a Model AA-1475 (Varian Analytical Instruments, Sunnyvale, CA, USA) with an air-acetylene flame and an hollow cathode lamp at 9 mA; As was detected at 193.7 nm (full operating conditions are listed). The detection limits were 2 ppb for each As form and 3 ppb for total As after mineralization of wine. Recoveries were 93, 91 and 85% for 10 ppb of inorganic As, 20 ppb of monomethylarsonic acid and 40 ppb of dimethylarsinic acid, respectively. RSD (n = 10) were 3.2-4.6%. The method can be used for studying exposure to As.
Arsenic Spectrophotometry Speciation Standard additions calibration

"Determination Of Sulfite In Food By Flow Injection Analysis"
J. AOAC Int. 1986 Volume 69, Issue 3 Pages 542-546
Sullivan JJ, Hollingworth TA, Wekell MM, Newton RT, Larose JE

Abstract: A method is described for the determination of sulfite levels in food products by flow injection analysis (FIA). The method is based on the decolorization of malachite green by SO2, which is isolated from the flowing sample stream by means of a gas diffusion cell. The FIA method has a detection limit in food sample extracts of 0.1 ppm SO2 (3 times peak height of blank), which corresponds to 1-10 ppm SO2 in a food product, depending on the extraction procedure used. At the 5 ppm SO2 level in a food extract, the precision of replicate injections is±1-2%. The method was tested on a variety of both sulfite-treated and untreated food products and the results compared favorably with those obtained by the Monier-Williams, colorimetric (pararosaniline), and enzymatic (sulfite oxidase) methods. The average differences from the FIA results were 19, 11, and 12%, respectively, for those samples (n = 12) above 50 ppm SO2. At lower levels the results were somewhat more erratic due to inaccuracies of the various methods at low concentrations. The method is based on the decolorization of malachite green (C. I. Basic Green 4) by SO2, which is isolated from the flowing sample stream by a gas diffusion cell; the decrease in absorbance is measured at 615 nm. The detection limit is 0.1 ppm, which corresponds to 1 to 10 ppm in a food product, depending on the extraction procedure used, which itself depends on the type of food being analyzed. For 5 ppm of SO2 in a food extract, the precision of replicate injections is ~1 to 2%. The proposed method was tested on sulfite-treated and untreated wine, apple juice, dried apricots, potatoes, pickled onions, shrimps, lettuce, dried apples and cabbage to give results in good agreement with those obtained by the Monier-Williams, pararosaniline colorimetric and sulfite oxidase methods. The mean differences from the proposed method were 19, 11 and 12%, respectively for the 12 samples with SO2 contents >50 ppm. At lower levels the results were somewhat more erratic. The construction of the flow injection apparatus is described in detail.
Sulfite Spectrophotometry Sample preparation Gas diffusion Extraction Method comparison

"Flow Injection Analysis Of Organic Acids And Amino Acids In Sake By Using PH-sensitive Glass Electrode And Acid Base Buffer Solution"
J. Flow Injection Anal. 1986 Volume 3, Issue 2 Pages 103-111
Toshihiko Imato, Chie Azemori, Yasukazu Asano and Nobuhiko Ishibashi

Abstract: To determine organic acids, the sample solution was injected into a stream of water, which was merged with a neutral H2PO4- - HPO42- buffer solution The pH change caused by acid - base reaction between the acid and HPO42- was detected with a flow-through pH electrode. Amino-acids were determined by injecting the sample into a stream of water, which was merged with formaldehyde to convert the analytes into stronger acids; the resulting solution was merged with alkaline phosphate buffer solution and the change in pH was monitored as before. Results correlated well with those of conventional neutralization titration.
Carboxylic acids Amino Acids Clinical analysis Electrode 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 Electrode Electrode Well stirred mixing chamber Method comparison Titrations

"Chemiluminescent Assay For Glycerol In Wine Using Flow Injection"
J. Food Sci. 1991 Volume 56, Issue 4 Pages 1097-1100
Puchades, R.;Lemieux, L.;Simard, R.E.

Abstract: Sample solution (29 µL) was injected into a carrier stream of 0.1 M phosphate buffer of pH 7.3 - 1 mM EDTA - 0.01 M ATP which passed through a reactor containing immobilized glycerol kinase and glycerol-3-phosphate oxidase (prep. described). The mixture then merged with streams of 0.01 M ferricyanide and 5 mM luminol before chemiluminescence was measured; all flow rates were 0.45 mL min-1. The calibration graph was rectilinear for 25 to 250 mg L-1 of glycerol (I); the detection limit was 12 mg L-1. The coefficient of variation (n = 10) for 50 mg L-1 of I was 2.6%. Sample throughput was 30 h-1 and the immobilized enzymes were stable for at least 3 months at 4°C.
Glycerol Chemiluminescence Buffer Immobilized enzyme

"Enzymic Determination Of Nitrate By Flow Injection Analysis"
LaborPraxis 1991 Volume 15, Issue 6 Pages 479-481
Kuecke, M.

Abstract: The procedure described is based on the reduction of NO3- to NO2- by E. coli cells, chromogenic reaction with sulfanilamide and N-(1-naphthyl)ethylendiamine dihydrochloride, and spectrophotometric detection. Details are given of the preparation of the cell suspension. For analysis of water, the suspension (20 ml) was diluted with 0.1 M phosphate buffer (pH 7.2) (400 ml), whereas for Ca-containing extracts the cell suspension (15 to 25 ml) was centrifuged and the cells were suspended in 0.2 M borate buffer (pH 7.2) (400 ml). Continuous-flow injection analysis was performed by mixing the cell suspension with the sample in phosphate buffer solution (pH 7.2) in a coil (6 m x 0.7 mm) at 37°C, followed by mixing with the color reagent in another coil (30 cm x 0.7 mm) and detection at 540 nm. The procedure is suitable for the analysis of waters, wines, nutrient solution and similar samples.
Nitrate Spectrophotometry Buffer Heated reaction Enzyme

"Direct Steady Temperature Platform GFAAS Determination Of Micro Amounts Of Lead In Grape Wine By The Steps Ramp Procedure"
Lihua Jianyan, Huaxue Fence 1996 Volume 32, Issue 2 Pages 86-88
Sun Xiaojuan

Abstract: Sample was treated with dilute HNO3 to a final HNO3 concentration of 0.2% and dilution of 1:2 or 1:3. Portions (10 µL) of the solution were mixed with 10 µL 2.5% NH4H2PO4 and the mixture was loaded by an automatic sampler onto the L'vov platform in the graphite tube for AAS. The injection temperature was 50°C and the ramp procedure was carried out with drying at 80°C (slope of 1 s; maintained for 15 s) as well as 120°C (slope 25 s; for 10 s), and ashing at 450°C (slope 10 s; for 10 s) as well as 700°C (slope 10 s; for 15 s), with Ar flow-rate 300 ml/min, and atomization at 1800°C (gas flow stopped). The atomization signal appeared as single peak. There was no matrix interference using both HNO3 and NH4H2PO4 as matrix modifiers. By standard-additions method, recoveries were 97-104% with RSD of 0.8-3.9%. Results were compared with those obtained by FIA.
Lead Spectrophotometry Interferences Standard additions calibration

"Determination And Evaluation Of Sodium Borohydride Releasable Mercury In Wine And Wine Containing Beverages"
Mitt. Klosterneuberg 1998 Volume 48, Issue 5 Pages 149-156
Herbst, Peter; Netzer, Michaela; Heili, Karl; Bandion, Franz

Abstract: An atomic-absorption-spectrometric (AAS) method for the determination of mercury releasable under given analytic conditions in wine and wine containing beverages on the basis of a continuous flow-injection system, a reduction of sodium boron hydride, cold vapor technique and amalgamation is described. In an investigation of 275 authentic Austrian wines of the 1997 vintage the highest value found was 197 ng mercury per litre wine. Compared to maximum level regulations with drinking water and grape juice the situation present with wine can be considered quite favourable. Mash fermented red wines showed a significantly lower mercury contamination than white and rose wines. With Austrian viticultural conditions regional factors and stage of ripeness of the grapes harvested did not influence the mercury contents of the resulting wines. Technological requirements for the quality assessment of processing aids used in wine production with respect to mercury transfer into the wine are discussed.
Mercury Spectrophotometry Volatile generation

"Flow Injection Analysis For Uric Acid By The Combined Use Of An Immobilized Uricase Reactor And A Peroxidase Electrode"
Nippon Kagaku Kaishi 1985 Volume 1985, Issue 2 Pages 189-192
Yao, T.;Sato, M.;Wasa, T.

Abstract: The sample (2 µL) is injected into a reactor containing immobilized urate oxidase. The carrier stream comprises 0.1 M borate buffer (pH 9.0) containing 0.2 M NaCl and 1 mM K4Fe(CN)6 and pumped at 1.5 mL min-1. The H2O2 generated in the reactor forms K3Fe(CN)6 in the presence of a peroxidase electrode. This electrode operates at only ~-50 mV vs. silver - Ag+, so that little interference is caused by other constituents of serum or urine. The peak current is rectilinearly related to uric acid concentration. in the range 0.2 to 8 mg dl-1. The peak width is ~30 s, so that 90 to 120 samples can be analyzed in 1 h with a coefficient of variation of 1 to 2%. Results show excellent agreement with those by the urate oxidase - u.v. method.
Uric acid Electrode Interferences Immobilized enzyme Method comparison Peak width

"Automated Determination Of Alcohol And Sugar In Wine By Continuous-flow-through Analysis"
Oesterr. Chem. Z. 1981 Volume 82, Issue 2 Pages 42-43
Kaufmann, F.

Abstract: The components of a commercial automatic analyzer are listed. The principles of the enzymatic determination of EtOH [64-17-5] with alcohol dehydrogenase, with the spectrometric determination of the amt. of NADH produced, and of glucose [50-99-7] and fructose [57-48-7] with hexokinase, glucose 6-phosphate dehydrogenase, phosphoglucoisomerase, and NADP are explained. (SFS)
Alcohol Ethanol Sugars Spectrophotometry

"Determination Of Sulfur Dioxide In Wine And Beer By Flow Injection Analysis"
Prumysl Potravin 1990 Volume 41, Issue 1 Pages 40-43
Krausova, J.;Jedlickova, J.

Abstract: A Tecator FIA-Star analyzer. was used with spectrophotometric detection (cf. Tecator Application Note, ASN 61-23/83). The concentration. of SO2 found in wine ranged from 2 to 35 mg l-1. Comparison with a titrimetric method for wine and a distillation method for beer showed r = 0.955 and 0.850, respectively.
Sulfur dioxide Tecator

"Automatic Analysis In Oenology"
Rev. Fr. Oenol. 1989 Volume 117, Issue 1 Pages 47-53
Bouvier, J.C.

Abstract: A review is presented, with 53 references, of the automatic analysis of must and wine by continuous-flow.

"Continuous-flow Analysis. Photometric Determination Of Nitrite"
J. Anal. Chem. 1993 Volume 48, Issue 1 Pages 55-60
Shirinova, A.G.;Rodionova, T.V.;Ivanov, V.M.;Beklemishev, M.K.;Zolotov, Y.A.

Abstract: 4-Nitroaniline (5 mM; 12 ml) was mixed with resorcinol (5 mM; 12 ml) and HCl (1M; 5 ml) and the mixture was diluted with water to 50 mL before the addition of NaOH (2M; 30 ml) and EDTA (0.125M; 20 ml). Sample solution (2 to 3 ml) was diluted to 10 mL with the above solution and analyzed by continuous-flow analysis using a model RFA-300 analyzer. (Alpkem, USA) with photometric detection at 550 nm. The calibration graph for nitrite was rectilinear from 0.07 to 4.6 µg mL-1. The detection limit was 46 µg L-1 and the coefficient of variation was 4% (n = 3). Up to 72 determinations can be made per hour. The method was applied to the analysis of wine. The precision of the method was similar to that of a flow injection method.
Nitrite Spectrophotometry Segmented flow Alpkem

"Monitoring Alcoholic Fermentation Of Red Wine By Electrochemical Biosensors"
Am. J. Enol. Vitic. 2003 Volume 54, Issue 1 Pages 39-45
Marco Esti, Giulia Volpe, Dario Compagnone, Giacomo Mariotti, Danila Moscone, and Giuseppe Palleschi

Abstract: Amperometric biosensors for the determination of glucose, fructose, ethanol, and glycerol were used to monitor alcoholic fermentation during red wine production in industrial-scale plants. Platinum-based probes, covered with appropriate enzyme membranes, were assembled in electrochemical flow-injection analysis systems. Before use, the biosensors were validated in must and wine samples by spectrophotometric procedures. The biosensors were applied during alcoholic fermentation in three wineries that used different red winemaking techniques. Results are reported and compared. Glucose, fructose, ethanol, and glycerol content varied with different kinetics corresponding to three characteristic phases: an early phase with no detectable variation of the analytes, an intermediate phase characterized by rapid sugar use, and a late phase with little variation of the concentration levels. In particular, glucose was consumed more rapidly than fructose, confirming that the former is the preferential sugar source for Saccharomyces cerevisiae. Experimental data demonstrated that the biosensors are useful tools for the close monitoring of alcoholic fermentation during industrial mass production of wine.
Glucose Ethanol Glycerol Fructose Electrochemical analysis Sensor Biochemical analysis Sensor Internal standard Process monitoring Process control

"Electrochemical Biosensors For Assays Of L-Malic And D-Lactic Acids In Wines"
Am. J. Enol. Vitic. 1996 Volume 47, Issue 1 Pages 11-16
M. Gilis, H. Durliat, and M. Comtat

Abstract: The knowledge of L-malic acid concentration is important for the follow-up of grape maturation and of malolactic fermentation; in the same way, D- lactic acid concentration gives information about the growth of lactic piqûre. A simple and inexpensive assay method is proposed with the use of amperometric biosensors developed for this specific application. The results are compared to those obtained with the enzymatic spectrophotometric method (Boehringer kit). The difference between the two measurement results shows that colored substances interfere with the compounds assayed in the case of red wine. To minimize this effect, two methods are proposed: a differential measurement or the addition of charcoal to the sample for the adsorption of colored substances. The short response time allows analysis of 100 samples every day, and the biosensor can work for one month with the same enzymatic solution.
l-Malic acid d-Lactic acid Biotechnology Sensor Sensor Spectroelectrochemistry Electrode Low cost

"Evaluation Of A Digital Blood Glucose Monitor For Measuring Residual Glucose In Wines"
Am. J. Enol. Vitic. 1998 Volume 49, Issue 2 Pages 225-228
Robert M. Cook, Bruce R. Devlin, Susan E. Ebeler, and Christian E. Butzke

Abstract: Current methods for accurately measuring residual sugar (RS) concentrations in wine can be time-consuming, requiring multiple preparation steps and careful training. Sugar test pills and strips are rapid and easy to use for monitoring RS concentrations from 1 to 20 g/L but only give an approximate RS concentration. Recently, hand-held, digital glucose testing monitors have become available for use by diabetics to accurately and rapidly monitor blood glucose concentrations. We evaluated one of these monitors for its sensitivity and accuracy in model wine solutions. Wines of varying RS concentrations were tested and the results compared to standard procedures. The influence of pH and ethanol and SO2 concentrations on the assay were investigated. The monitor showed promise for measuring glucose concentrations of 1 g/L or less in wines. In model wine solutions, a nonlinear response was obtained with glucose concentrations of 2 to 10 g/L. The evaluated type of system is not suitable for routine monitoring of fermentations in a winery.
Glucose Ethanol Sulfite Sensor Method comparison Apparatus Detector

"Sequential Injection Analysis Of Free And Total Potassium In Wines Using Potentiometric Detection And Microwave Digestion"
Am. J. Enol. Vitic. 2003 Volume 54, Issue 1 Pages 46-49
N&eacute;stor Z&aacute;rate, Alberto N. Ara&uacute;jo, Maria Concei&ccedil;&atilde;o B.S.M. Montenegro, and Ricardo P&eacute;rez-Olmos

Abstract: An automatic procedure for the determination of free and total potassium in wines is described that combines sequential injection analysis with potentiometric detection. A sequential injection mounting is coupled to a microwave system to conduct the on-line digestion of the sample, thereby making the injection of samples possible without prior treatment. Free potassium was determined by injecting 110 µL of sample and forwarding it to the detection system. In the evaluation of total potassium, the sample was previously digested with 390 µL of hydrogen peroxide for 60 seconds at 700 W in a microwave oven. Using an optimized mounting, 10 samples of different wine types were analyzed (white, red, and port), and results were then compared with those provided by flame emission photometry. Relative standard deviations obtained were always below 3% and sampling rate attained was about 14 samples per hour.
Potassium Sample preparation Sample preparation Spectrophotometry Potentiometry Apparatus Automation

"Direct Determination Of Total Sulfur In Wine Using A Continuum-source Atomic-absorption Spectrometer And An Air–acetylene Flame"
Anal. Bioanal. Chem. 2005 Volume 382, Issue 8 Pages 1877-1881
Mao Dong Huang, Helmut Becker-Ross, Stefan Florek, Uwe Heitmann and Michael Okruss

Abstract: Determination of sulfur in wine is an important analytical task, particularly with regard to food safety legislation, wine trade, and oenology. Hitherto existing methods for sulfur determination all have specific drawbacks, for example high cost and time consumption, poor precision or selectivity, or matrix effects. In this paper a new method, with low running costs, is introduced for direct, reliable, rapid, and accurate determination of the total sulfur content of wine samples. The method is based on measurement of the molecular absorption of carbon monosulfide (CS) in an ordinary air-acetylene flame by using a high-resolution continuum-source atomic-absorption spectrometer including a novel high-intensity short-arc xenon lamp. First results for total sulfur concentrations in different wine samples were compared with data from comparative ICP-MS measurements. Very good agreement within a few percent was obtained.
Sulfur Spectrophotometry Method comparison