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 -> beer

Citations 80

"Anodic Stripping Voltammetry Of Copper At Insonated Glassy Carbon-based Electrodes: Application To The Determination Of Copper In Beer"
Analyst 1999 Volume 124, Issue 7 Pages 1053-1057
César Agra-Gutiérrez, Joanna L. Hardcastle, Jon C. Ball and Richard G. Compton

Abstract: The suitability of ultrasound-assisted anodic stripping voltammetry (sono-ASV) for the detection of total copper content in beer using both mercury thin film and glassy carbon electrodes has been investigated. An immersion horn probe is introduced into a small thermostatted conventional three electrode cell (20 cm(3)) opposite the working electrode: an ex situ mercury plated Nafion(R)-coated mercury film electrode or a bare glassy carbon electrode. Minimal sample pre-treatment is required which consists of acidification of the beer with dilute nitric acid and out-gassing with argon. After the deposition of copper (as the metal or its amalgam) on the electrode in the presence of ultrasound, a square wave scan is employed to get the analytical signal. In the absence of ultrasound, electrode passivation by organic species and lower rates of mass transport prevent the observation of any measurable signals. In situ cavitational cleaning of the electrode by insolation maintains the electrode activity. Total copper content levels in the range of 100 to 300 µg Cu L-1 were determined by sono-ASV using both electrode substrates and showed excellent agreement with values provided by an independent method. This highlights the validity of the sono-ASV method as a useful electroanalytical technique in hostile media.
Copper Electrode Electrode Electrode Ultrasound

"Determination Of The Substrates Of Dehydrogenases In Biological Material In Flow Injection Systems With Electrocatalytic NADH Oxidation"
Anal. Chim. Acta 1984 Volume 163, Issue 1 Pages 299-303
A. Schelter-Graf, H. -L. Schmidt and H. Huck

Abstract: Applications are described of the NADH-sensitive system described previously (Huck et al., Anal. Abstr., 1984, 46, 8J126) that incorporated epoxyacrylic resin-bound dehydrogenases and a modified graphite electrode. The determination of D- and L-lactate in butter, L-glutamate in beef cubes, and ethanol in beer, and the control of the enzymatic hydrolysis of N-acetyl-DL-leucine by aminoacylase are discussed. The results obtained agreed well with those by spectrophotometric methods.
Ethanol l-Glutamate d-Lactate l-Lactate N-Acetyl-DL-leucine Electrode Potentiometry Method comparison Reactor Enzyme

"Automated Flow Injection Extraction Method For Determination Of Bittering Compounds In Beer"
Anal. Chim. Acta 1986 Volume 187, Issue 1 Pages 339-342
Ylva Sahleström, Sigrid Twengström and Bo Karlberg

Abstract: The flow injection procedure described is an adaptation of a standard manual method. A 100 µL portion of degassed beer is injected into a 0.1 M HCl carrier stream (1 mL min-1), which, after passing through a 50-cm mixing coil, is mixed with 2,2,4-trimethylpentane (0.5 mL min-1). The resulting stream is passed through a 200-cm mixing coil and thence into a phase-separation unit equipped with a PTFE membrane (cf. Ibid., 1986, 179, 315), and the absorbance of the separated organic phase is measured at 275 nm in a flow-through spectrophotometer. Results for 22 products agreed well with those obtained by the manual procedure. The sampling rate is 60 h-1.
Acids, bitter Isohumulone Isocohumulone Isoadhumulone Spectrophotometry Sample preparation Extraction Method comparison Organic phase detection Phase separator Tecator Teflon membrane

"Flow Injection Determination Of Starch And Total Carbohydrate With An Immobilized Glucoamylase Reactor And Pulsed Amperometric Detection"
Anal. Chim. Acta 1988 Volume 204, Issue 1-2 Pages 43-51
Larry A. Larew, David A. Mead, Jr and Dennis C. Johnson

Abstract: Oligosaccharides having a degree of polymerization »2 were determined by using an immobilized glucan 1,4-α-glucosidase(I) reactor with pulsed amperometric detection (PAD) of the glucose produced. I was immobilized on to porous silica (LiChrospher) and the product was packed into a stainless-steel column (5 cm x 4.1 mm). Samples were dissolved in 0.2 M Na acetate buffer (pH 4.8). The flow injection system is illustrated diagrammatically. The reactor achieved 98% conversion of starch to glucose. The sensitivity of PAD for soluble starch was increased 26-fold by first passing the sample through the I reactor. The method was used to determine total carbohydrate in beer.
Starch Carbohydrates Amperometry Immobilized enzyme Silica

"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

"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

"Selective Determination Of Dextrins By Liquid Chromatography With Post-column Enzymic Reaction, Using Co-immobilized Enzymes"
Anal. Chim. Acta 1992 Volume 257, Issue 1 Pages 79-87
F. Ortega

Abstract: The CPG-10 support (Serva; pore diameter 51.5 nm, paricle size 37 to 74 µm) was treated with 10% (3-aminopropyl)triethoxysilane solution in toluene, the product was activated with glutaraldehyde, and glucan 1,4-α-glucosidase, glucose dehydrogenase and aldose 1-epimerase were co-immobilized on its surface from 0.1 M phosphate buffer medium (pH 6) at ambient temperature and then at 4°C. Parameters influencing enzyme behavior were optimized by means of three flow injection systems in which reactors containing the immobilized enzymes were incorporated (diagrams given). For the determination of dextrins in wort and beer, diluted samples were cleaned up by membrane filtration (0.22 µm) and passage through Sep-Pak cartridges, and portions (20 µL) were then injected into a column of Aminex HPX-42-A (at 65°C) preceded by a Micro-Guard column (Bio-Rad) for HPLC with water as mobile phase. The eluate passed via a T-piece into a flow of 3 mM NAD+ in 0.3 M phosphate buffer of pH 6 and thence through the enzyme reactor (at 40°), and the final product NADH was detected at 340 nm. Rectilinear calibration graphs based on peak area were obtained for the various dextrins, and detection limits ranged from 200 to 500 ng. The co-immobilized enzymes remained stable for 55 days when stored in 1 M NaCl at 4°.
Dextrins HPLC Amperometry Spectrophotometry Post-column derivatization Immobilized enzyme Controlled pore glass Biorad Heated reaction

"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

"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 Künnecke*

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

"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

"Study Of The Enhanced Chemiluminescence From The Luminol--horseradish Peroxidase--hydrogen Peroxide--p-coumaric Acid System At Very Short Times: Stopped-flow Selective Determination Of P-coumaric Acid In Beers"
Anal. Chim. Acta 1995 Volume 310, Issue 3 Pages 399-406
F. García Sánchez*, A. Navas Díaz and J. A. González García

Abstract: p-Coumaric acid has a greater enhancing effect on the chemiluminescence of the luminol-H2O2-horseradish peroxidase system, at low concentration, than other phenolic acids studied. We have used this effect to study the variations of the chemiluminescent signal with luminol, hydrogen peroxide, p-coumaric acid, horseradish peroxidase concentrations and pH, using the stopped-flow technique, by monitoring the initial reaction rate. The interference effects of other phenolic acids on the enhanced chemiluminescence with p-coumaric acid (25 nM) were negligible at similar concentrations of phenolic acid. We monitored the chemiluminescence intensity at 10 s for the determination of p-coumaric acid in beers. The detection limit was ~0.7 nM and the linear range was 0-12.5 nM. The precision of the method, expressed as a relative standard deviation, was 2.5%.
4-Coumaric acid Chemiluminescence Stopped-flow

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate By Flow Injection Analysis"
Talanta 1996 Volume 43, Issue 7 Pages 1009-1018
M. J. Ahmeda, C. D. Stalikasa, S. M. Tzouwara-Karayannia and M. I. Karayannisa,*

Abstract: Meat products, flour, soil, beer and cheese were prepared and digested by the AOAC method ['Official Methods of Analysis of the Association of Official Analytical Chemists', Helrich (Ed.), Association of Official Analytical Chemists, Arlington, VA, USA, 1990]. The digests were filtered and the filtrate or filtered water was diluted with 0.4 M NH4Cl. The prepared samples or standards were injected into a carrier stream (0.4 ml/min) of 0.4 M NH4Cl, the stream was split into two and one stream passed through a glass reaction column (2 cm x 3 mm i.d.) packed with copper particles and a reduction column (10 cm x 3 mm i.d.) packed with copperized cadmium granules. The reduced stream merged with a reagent stream (1 ml/min) of 7.24 mM 3-nitroaniline/3.86 mM N-(1-naphthyl)- ethylenediamine dihydrochloride (1:5), the resulting stream passed through a reaction coil (50 cm) and the absorbance was measured at 535 nm. The second part of the stream by-passed the reduction columns, merged with the reagent stream and the absorbance was measured. Calibration graphs were linear for 0.01-2.2 µg/ml of nitrite and 0.1-3.5 µg/ml of nitrate with detection limits of 1 ng/ml and 10 ng/ml, respectively. The RSD (n = 5) were 0.1-2% over the calibration range for nitrate and nitrite. The permissible levels of interfering ions are tabulated.
Nitrate Nitrite Sample preparation Spectrophotometry Interferences Column Reduction column

"Application Of Biosensor With Amperometric Detection For Determining Ethanol"
Analyst 1994 Volume 119, Issue 8 Pages 1843-1847
Mária Váradi and Nóra Adányi

Abstract: A thin-layer enzyme cell was constructed by immobilizing alcohol oxidase (from Pichia pastoris) on a protein membrane. The cell was incorporated in a flow injection system and used for the determination of ethanol. Sample (20 µL) was injected into a stream (0.23 ml/min) of 40% phosphate buffer of pH 7.38 and the solution was passed to a dialyser unit containing a polysulfone membrane. The analyte diffused through the membrane and was transported in a stream of 40% phosphate buffer of pH 7.38 (0.23 ml/min) to the thin-layer enzyme cell thermostatted at 27°C. The product of the enzymatic reaction was measured by means of a flow-through amperometric detector at a potential of 600 mV vs. Ag/AgCl. A diagram of the system used is given. The calibration graph was linear from 1-8% of ethanol; the detection limit was 0.1%. The method was used to determine ethanol in beer.
Ethanol Amperometry Sensor Electrode

"Determination Of Ethanol In Beer By Flow Injection Dual-pulse Staircase Voltammetric Detection"
Analyst 1996 Volume 121, Issue 3 Pages 369-372
Yingsing Fung and Songying Mo

Abstract: Beer was filtered and the filtrate was diluted with 0.1 M NaOH. A 100 µL portion of the resulting solution was injected into a carrier stream (0.5 ml/min) of 0.1 M NaOH. Ethanol was determined by dual-pulse staircase voltammetry at a Pt electrode: the electrode was initially held at 0 V vs. Ag/AgCl, stepped up to +0.7 V for 1.5 s, then stepped back to -0.8 V for 1 s before scanning from -0.8 to +0.2 V with 10 mV potential steps and a 0.5 V/s scan rate. The peak current was recorded at +0.05 V. The calibration graph was linear fro 0.01-10 mM ethanol, the detection limit was 0.6 nM and the RSD (n = 8) at the 0.03 mM ethanol level was 1.9%. The throughput was 60 samples/h. The results obtained agreed with those obtained by the reference AOAC method.
Ethanol Voltammetry

"Vapor Generation Fourier Transform Infrared Direct Determination Of Ethanol In Alcoholic Beverages"
Analyst 1996 Volume 121, Issue 7 Pages 923-928
Amparo Pérez-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

"Online Flow Injection Pervaporation Of Beer Samples For The Determination Of Diacetyl"
Analyst 1997 Volume 122, Issue 2 Pages 119-122
José M. Izquierdo-Ferrero, Juan M. Fernández-Romero and María D. Luque de Castro

Abstract: Beer was ultrasonicated for 5 min then 2 mL was injected into an aqueous carrier/donor stream at a flow rate of 0.3 ml/min and the mixture was passed through a pervaporation cell (Mattos et al., Talanta, 1995, 42, 755) maintained at 90°C. The diacetyl evaporated from the donor stream diffused through a hydrophobic membrane and was collected in a static reagent/acceptor solution of 125 mM α-naphthol /100 mM creatine/750 mM NaOH of pH 12. After 5 min pervaporation, the acceptor solution was pumped at a flow rate of 1.8 ml/min to the detector and the absorbance of the colored product was measured at 530 nm. A diagram of the manifold used is given. The calibration graph was linear from 10^-2000 ng/ml biacetyl; the detection limit was 5 ng/ml and the RSD was 2.6-3% (n value not given). The throughput was 8 samples/h. Recoveries were 94-107% diacetyl added to beer samples. The results obtained agreed with those obtained by a conventional distillation/spectrophotometric method.
Diacetyl Spectrophotometry Pervaporation Method comparison Hydrophobic membrane

"Predicting Organoleptic Scores Of Sub-ppm Flavor Notes. 2. Computational Analysis And Results"
Analyst 1998 Volume 123, Issue 10 Pages 2057-2066
Timothy C. Pearce and Julian W. Gardner

Abstract: In Part 1 of this paper (T. C. Pearce and J. W. Gardner, 1998) we describe a novel method for predicting the organoleptic scores of complex odors using an array of non-specific chemosensors. The application of this method to characterizing beer flavor is demonstrated here by way of predicting a single organoleptic score as defined under the joint EBC/ASBC/MBAA international flavor wheel for beer. An experimental study was designed to test the accuracy of the odor mapping technique for this prediction of organoleptic scores of adde reference compounds within a chemical complex lager beer background. Using the flow injection analyzer (FIA) system comprising 24 conducting polymer sensors, also described in Part 1, sampling was conducted on spiked lager beers. A di-Me sulfide spike was added at the 20-80 ppb (v/v) level to simulate a range of organoleptic scores (0-5.5 out of 10) for flavor note #0730 - 'cooked vegetable'. A certain amount of sensor drift was observed over the 12 d testing period which is shown to account for significant variance in the data-set as a whole. The effect of the sensor drift was reduced by applying a linear drift model, which may be generally applied when the between-class variance due to the difference in odors is small when compared with the within-class variance due to the drift, which increases approximately linearly over time. Careful use of this drift compensation model, coupled with judicious selection of pre-processing and pattern recognition techniques, maximized the between-class variance and so improved the overall classification performance of the system. After applying detailed exploratory data anal., statistical, and neural classifier techniques, the organoleptic score was predicted with an accuracy of ±1.4 (out of 10) and 95% confidence. Our results show that it is possible to generate subjectively defined organoleptic flavor information using multi-sensor arrays and associated data-processing that is comparable in accuracy to sensory and GC-based techniques.
Dimethylsulfide Sensor Sensor Method comparison Chemometrics

"Predicting Organoleptic Scores Of Sub-ppm Flavor Notes. 1. Theoretical And Experimental Details"
Analyst 1998 Volume 123, Issue 10 Pages 2047-2055
Timothy C. Pearce and Julian W. Gardner

Abstract: Most existing electronic nose systems have limited commercial application since they only provide a relative description of the flavor under investigation, rather than one against a universal standard However, the development of a set of universally accepted standards for flavor description has been problematic due to the lack of any comprehensive model relating the mol. structure of an odorant with its flavor-impact during the act of perception. Instead, industries have tended to develop their own flavor models (flavor terminol. systems) for specific consumer products that are based upon practical experience of a particular food, cosmetic, or beverage. We report here on the novel application of chemical multi-sensor arrays to the prediction of organoleptic flavor notes, as defined under a specific terminol. system suitable for describing and communicating specific flavors. A novel odor mapping scheme is proposed that may be applied generally to multi-sensor arrays and provides more detailed characterization of odor quality than is currently achievable. As part of our study, a flow injection analyzer (FIA) system has been developed that combines chemical and electronic hardware driven by a microcomputer to achieve accurate and independent control over odor-stream temperature, flow-rate and flow profile, sensor head temperature and sample times. An array of 24 conducting polymer sensors (11 different types) is used within the FIA system, giving an overall experimental coefficient of variation below 7%. The application of this odor mapping technique is demonstrated by way of an experimental study, using the FIA system reported here. The details for this study are given in Part 1, and the computational anal. of the data is carried out in Part 2 (T. C. Pearce and J. W. Gardner, 1998).
Sensor Sensor Chemometrics

"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

"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

"Flow Injection Extraction In Theory And Practice"
Fresenius J. Anal. Chem. 1988 Volume 329, Issue 6 Pages 660-662
Bo Karlberg

Abstract: Flow injection schemes involving solvent extraction are reviewed, with examples. Procedures are given for the extractions of caffeine from beverages, anionic surfactants from aqueous samples, codeine from drugs, bitterness compounds from beer, and phenol from water. The organic extractant is 2,2,4-trimethylpentane (for beer) or CHCl3 (others). A typical system is characterized by low comsumption of organic phase (0.5 to 2 mL per sample), low sample volume (20 to 200 µL) and high sample throughput (45 to 120 h-1). (9 references).
Bittering compounds Caffeine Codeine Phenol Surfactants, anionic Sample preparation Extraction Review Tecator Theory

"Flow Injection Analysis Of Zinc And Cobalt In Beverages, Biological, Environmental, And Pharmaceutical Samples"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 7-8 Pages 571-576
S. G. Aggarwal and K. S. Patel

Abstract: A new, simple, rapid, and selective flow injection analysis (FIA) method for the spectrophotometric quantification (speciation of inorganic and organic form) of Zn and Co with NH4SCN and malachite green (MG) in the presence of surfactants (CPC and TX-100) is described. The value of apparent molar absorptivity of the Zn- and Co-complexes are 1.23 x 104 and 8.67 x 103 L mol-1 cm-1 at absorption max., 635 nm, respectively. The detection limit (amt. causing a peak height >3 s) is 15 ppb Zn and 20 ppb Co, whereas their optimum working ranges for the quant. determinations are 0.05-2.0 ppm Zn and 0.07-2.5 ppm Co in the real samples. The sample throughput of the method is 120 samples/h at the flow rate of 5.0 mL/min with RSD of <1%. The method is free from interferences of almost all ions which are commonly associated with these metals in the complex materials. The composition of the complexes and their reaction mechanism involved are discussed. The effect of FIA and anal. variables for the determination of the metals are optimized. The method was applied to the quantification of Zn and Co in beverages, biol., environmental, and pharmaceutical samples.
Zinc Cobalt Spectrophotometry Speciation pH gradient Surfactant Interferences Complexation

"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

"Photoelectrochemical Detection Of Alcohols"
Electroanalysis 1992 Volume 4, Issue 4 Pages 439-445
Joseph N. Barisci, Gordon G. Wallace

Abstract: The proposed method is based on the reaction of the analyte with a photo-sensitized quinone (e.g. benzoquinone or anthraquinone) in aqueous acetonitrile, followed by the amperometric determination of the product hydroquinone at a vitreous-carbon electrode. In a flow injection procedure, the sample was injected into aqueous 80% acetonitrile containing 80 mM NaClO4 and 10 ppm benzoquinone (flow rate 0.5 mL min-1) and amperometry was performed at an applied potential of 0.70 V vs. Ag - AgCl. Calibration graphs were rectilinear for up to 300 ppm of aliphatic alcohols up to C4 and limits of detection were ~2 ppm. Limits of detection could be improved by ~50% by use of pulsed amperometric detection. Results for ethanol in two beers and a sample of vodka were in good agreement with those obtained by GC - FID. The proposed technique has also been applied in the determination of alcohols by HPLC on a reversed-phase C18 column with aqueous 50% acetonitrile containing 50 mM NaClO4 and 10 ppm benzoquinone as mobile phase.
Alcohols Amperometry Electrode Method comparison

"Amperometric Differential Determination Of Ascorbic Acid In Beverages And Vitamin C Tablets Using A Flow Cell Containing An Array Of Gold Microelectrodes Modified With Palladium"
Electroanalysis 1998 Volume 10, Issue 13 Pages 887-890
Renato C. Matos, M&aacute;rcio A. Augelli, Jairo J. Pedrotti, Claudimir L. Lago, L&uacute;cio Angnes

Abstract: A simple and attractive method for quantification of ascorbic acid (AA) in beers, soda, natural juices, and commercial vitamin C tablets was developed by combining flow injection analysis and amperometric detection. An array of Au microelectrodes electrochemically modified by deposition of Pd was employed as working electrode which was almost unaffected by fouling effects. AA was quantified in beverages and vitamin tablets using amperometric differential measurements. The method is based on three steps involving the flow injection of the sample plus a standard addition of AA, of the pure sample, and of the enzymatically-treated sample. The enzymatic treatment was carried out with Cucumis sativus tissue, which is a rich source of ascorbate oxidase, at pH 7. The calibration plots for freshly prepared AA standards were linear in the concentration. range of 0.18-1.8 mg/L with a relative standard deviation (RSD) <1%, while for real samples the deviations were 2.7-8.9%.
Ascorbic acid Amperometry Electrode Electrode Differential detection Standard additions calibration Enzyme

"Chemical Reaction Detection Of Catechins And Proanthocyanidins With 4-dimethylaminocinnamaldehyde"
J. Chromatogr. A 1989 Volume 467, Issue 1 Pages 185-193
D. Treutter

Abstract: The cited flavanols were determined in crude plant extracts and beverages by HPLC on a column (25 cm x 4 mm) of Hypersil ODS (3 µm), with gradient elution from 5 to 90% of methanol in 5% acetic acid. Post-column derivatization was carried out with 1% 4-dimethylaminocinnamaldehyde solution in methanolic 1.5 M H2SO4 and detection was at 640 nm. Sensitivity was improved 200 to 40,000-fold for (-)-epicatechin compared with other phenols and substituted indoles; the detection limit was 2.5 ng. For terpenes, this factor ranged from 4000 to 2,000,000. The selective detection of catechins and proanthocyanidins extracted from tea and beer is described.
Catechins Proanthocyanidins HPLC Spectrophotometry Column Post-column derivatization Sensitivity Detection limit

"Trapping System For Trace Organic Volatiles"
J. Chromatogr. A 1991 Volume 586, Issue 2 Pages 315-322
Tom&aacute;s Jurs&iacute;k, Karel Str&aacute;nsk&yacute;* and Karel Ubik

Abstract: A technique is described for the collection and concentration of volatile compounds produced by plants, animals and other materials which is a modification of the continuous-flow system based on absorption of volatiles in a low amount of solvent at low temp (cf. 'Proceedings of a Conference on Insect Chemistry and Ecology Tabor, Aug 12-18, 1990', Hrdy (Ed.), Academia, Prague, 1991, p.327). The trapping device (illustrated) works offline and the concentrated analytes are analyzed by GC (details given). The method was evaluated in the analysis of C8 to C22 alkanes and subsequently applied in the analysis of coffee beans, spruce bark, black pepper, beer and PVC floor covering. Chromatographs are presented. The advantages and disadvantages of the trapping device are tabulated.
Organics, volatiles GC C8 Apparatus

"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

"Flow Injection Analysis Of Oxalate In Foods Using Titanium(IV)-porphyrin Reagent"
Anal. Sci. 1995 Volume 11, Issue 2 Pages 245-249

Abstract: Homogenized fruit (or vegetable; 20 g) was dissolved in 60 mL water, the pH was adjusted to 2-3 with HCl and the solution was incubated at 50°C for 15 min. On cooling the solution was adjusted to pH 2 with KOH, diluted to 100 mL with water and filtered (0.45 µm). A 20 µL portion of the diluted solution was injected into a stream of 0.05 M succinate buffer of pH 3 (0.4 ml/min) and passed through an immobilized oxalate oxidase column (3 cm x 2 mm i.d.). The H2O2 produced was reacted with a stream of 30 µM-Ti(IV)-porphyrin reagent (details given) at 0.4 ml/min in a mixing coil (15 m x 0.5 mm i.d.) and the absorbance of the peroxo complex formed was measured at 450 nm. The calibration graph was linear from 0.5-250 µM-oxalate (100-5000 pmol/20 µL injection). The RSD (n = 10) was 0.48% at 25 µM-oxalate (500 pmol/20 µL injection). The method was also applied to the analysis of beer and millet jelly solutions.
Oxalate Spectrophotometry Immobilized enzyme

"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

"Determination Of Orthophosphate, Ammonia, Glucose, And Glutamate Using A Bioprocess Solution Analyzer"
Am. Biotechnol. Lab. 1998 Volume 16, Issue 1 Pages 42-42
Stieg, S.

Abstract: The BIO+ benchtop analyzer (Lachat Instruments, Milwaukee, WI) combines both enzymatic amperometric biosensor methods for glucose and glutamate determination and colorimetric methods for determination of orthophosphate and ammonia. A flow injection analysis (FIA) platform is used for simultaneous determination of ≤4 nutrients or metabolic byproducts. The analyzer was used during a 4-wk evaluation to determine ammonia and orthophosphate in bioreactor beers. The dynamic ranges for the BIO+ FIA methods were 10-1000 mg NH3/L and 5-1226 mg PO43-/L. Speed of analysis, accuracy, and precision were comparable with results from a Biolyzer (Eastman Kodak, Rochester, NY). Color interference was <5% of the lowest calibration standard Spike recoveries were ≥90% for all samples.
Phosphate Ammonia Glucose Glutamate Amperometry Sensor Spectrophotometry Process monitoring Interferences Method comparison

"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

"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

"Determination Of Total Polyphenols In Beer By Flow Injection Analysis"
Food Chem. 1991 Volume 40, Issue 1 Pages 1-8
Miguel Peris, Dieter M&uuml;ller and Angel Maquieira*

Abstract: Beer was degassed for 10 min. in an ultrasonic bath, diluted with water and injected into a stream of 1% Na2CO3 and merged with a Folin-Ciocalteu reagent stream, the resulting complex was monitored at 750 nm. The method was compared with the international official method in which the sample stream consisted of carboxymethyl cellulose - EDTA and the reagent stream was 3.5% ammonium ferric citrate merged with a 1% NH4OH stream. A number of commercial samples were analyzed by both methods; results obtained by the present method were consistently higher than those obtained by the official method.
Phenols, poly EDTA

"New Flow Injection Spectrophotometric Method For The Determination Of Tannins In Tea And Beer Using Iron(III) And 1,10-phenanthroline"
Food Chem. 1993 Volume 47, Issue 2 Pages 201-204
Consuelo Tom&agrave;s, Mercedes Celeste, Andreu Cladera, Enrique G&oacute;mez, Jos&eacute;Manuel Estela and V&iacute;ctor Cerd&agrave;

Abstract: Tea was extracted for 1 h with boiling water and a portion (105 µL) of the filtered extract or degassed beer was injected into a stream of 0.4 M iron(III) chloride hexahydrate which was then merged with a stream of 0.5 M acetic acid of pH 3.5, followed by a stream of 15 mM 1,10-phenanthroline. All flow rates were 0.7 ml/min. The reaction mixture was passed through a mixing loop (0.5 m) and the difference in absorbances at 510 nm and 680 nm was recorded. Calibration graphs were linear for 2 mg/l of gallic acid. Recoveries were >88%. Sulfur dioxide and ascorbic acid interfered.
Tannins Gallic acid Sample preparation Spectrophotometry Interferences

"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

"Continuous-flow Analysis In Brewery Analysis"
GIT Fachz. Lab. 1993 Volume 37, Issue 8 Pages 657-658
Baier, B.;Lueck, M.;Mueke, O.;Harms, J.;Krueger, E.

Abstract: The potential of the cited technique in the control of the brewing process is discussed. It was applied to the determination of anthocyanogens, total polyphenol content and free amino-N in beer and wort. Precision and accuracy were comparable with those of the brewery standard wet chemistry methods.
Anthocyanogens Polyphenol Nitrogen, amino acid, free Process control

"Flow Injection Determination Of Sodium, Potassium, Calcium, And Magnesium In Beer By Flame Emission And Atomic Absorption Spectrometry"
J. Agric. Food Chem. 1997 Volume 45, Issue 4 Pages 1269-1272
S&iacute;lvia M. V. Fernandes and, Ant&oacute;nio O. S. S. Rangel, and Jos&eacute; L. F. C. Lima

Abstract: The normal ranges of the four cations in beers are such that substantial dilution is required to bring samples within the linear concentration ranges. Two manifolds were designed to achieve this. In one, samples (95 µL) were injected into a water carrier stream (6 ml/min), reaching a splitting point, where about 65% of the stream was rejected. The original carrier was further diluted with water (5.4 ml/min) into which a reagent plug of La(III) solution (1% in 0.6 M HCl, 0.12 ml) was injected, at a time calculated so that the diluted sample and the modifier arrived at the confluence together. After a further mixing coil, Na(I) and K(I) were determined by flame photometry, with an air/propane flame and Ca(II) was determined by AAS. In the second manifold, samples (0.2 ml) were injected into a water carrier stream (2.5 ml/min), mixed with 0.3 M HNO3 (2.5 ml/min) and passed to a dialysis unit, where the receptor solution was a plug of the La(III) solution (0.5 ml) in a water carrier (5 ml/min) timed to arrive at the same time as the sample. The Mg(II) was determined by AAS. These methods gave results in good agreement with those by the corresponding manual methods, with a sampling rate of 120-200 samples/h and greatly reduced consumption of the expensive La(III) reagent.
Calcium Magnesium Potassium Sodium Spectrophotometry Spectrophotometry Dialysis Dilution Method comparison

"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

"Direct Assay Of S-methylmethionine Using High Performance Liquid Chromatography And Fluorescence Techniques"
J. Am. Soc. Brew. Chem. 1986 Volume 44, Issue 1 Pages 1-6
Jean Pierre Dufour

Abstract: Malt flour was extracted with 0.1% trifluoroacetic acid(I) at 0°C. To the extract or to a sample of wort or decarbonated beer were added 1 mM L-2-amino-3-guanidinopropionic acid (internal standard) and 0.1% I - methanol (7:3). The solution was cleaned up on a Sep-Pak C18 cartridge. The eluate was analyzed by HPLC on a Waters amino-acid column with post-column derivatization of S-methylmethionine with phthalaldehyde and fluorimetric detection at 460 nm (excitation at 355 nm). The limit of determination was 0.2 µg g-1 of S-methylmethionine in dry malt.
S-Methylmethionine HPLC Fluorescence Post-column derivatization

"Application Of The Calcofluor Flow Injection Analysis Method For Determination Of β-glucan In Barley, Malt, Wort, And Beer"
J. Am. Soc. Brew. Chem. 1988 Volume 46, Issue 3 Pages 76-81
Sten Aastrup, and Kim G. J&oslash;rgensen

Abstract: Mixed linkage (1?3)(1?4)-?-d-glucan, the main constituent of barley endosperm cell walls, has been known for decades to be a troublesome compound in malting and brewing. Great efforts have therefore been made in order to assay ?-glucan. A new convenient and simple method of extracting the total ?-glucan in barley and malt is described in this paper. The ?-glucan in solution is subsequently assayed using flow injection analysis, by which ?-glucan and the fluorochrome, Calcofluor, are mixed. ?-Glucan in wort and beer can be assayed directly. The increase in fluorescence intensity is observed using a spectrofluorimeter. This method offers advantages over other methods with respect to the number of operational steps involved and the number of samples that can be analyzed per day. High correlation was found between the new method and enzymatic methods recently described.
β-Glucan Fluorescence Sample preparation Extraction

"Automated Bitterness Determination Of Beer Utilizing A Micro Phase Separator And Flow Injection Analysis"
J. Am. Soc. Brew. Chem. 1990 Volume 48, Issue 1 Pages 18-21
Kevin J. Switala and Karl G. Schick

Abstract: An automated method is described for determining bitterness in beer utilizing a unique µphase separator and flow injection analysis (FIA). In the FIA method, a fixed volume of degassed beer at room temperature is injected into an unsegmented carrier stream containing 0.3N hydrochloric acid, which is subsequently merged with an immiscible isooctane stream. After on-stream mixing, the organic isooctane phase is extracted with a µphase separator, and the absorbance of the organic phase is determined at 275 nm. The material, construction, and design of the µphase separator are discussed, and the separation of the isooctane from the aqueous phase is described.
Bittering compounds Phase separator Automation

"A Flow Injection Analyzer For Determining The Bitterness Of Wort And Beer"
J. Am. Soc. Brew. Chem. 1993 Volume 51, Issue 2 Pages 51-53
Shuso Sakuma, Choji Kikuchi, Masahiro Kowaka, and Masao Mawatari

Abstract: A flow injection analyzer for determining wort and beer bitterness was developed. A degassed beer sample or a diluted, filtered wort sample is injected into a carrier stream of water containing a surfactant, immediately followed by simultaneous addition of 0.6N hydrochloric acid and isooctane. After mixing in a Teflon tube, the organic phase is separated with a Teflon membrane, and the absorbance at 275 nm is determined. Using this automated method, it is possible to determine the bitterness of wort or beer within a range of 0-50 bitterness units (BU). The coefficient of variation was 0.5% for beer and 0.7% for wort. The correlation coefficient between this method and the ASBC method was 1.000. Values obtained with this method and the ASBC method generally vary by less than 0.5 BU.
Bittering compounds Spectrophotometry Teflon membrane Surfactant Organic phase detection

"Report Of 1997-BCOJ Collaborative Work. High Molecular Weight β-glucan Content In Beer"
J. Am. Soc. Brew. Chem. 1998 Volume 56, Issue 3 Pages 129-130

Abstract: β-Glucan in beer was determined by post-column Calcofluor flow injection analysis The reproducibility coefficient of variation was 4.2 - 5.1%, the standard deviation was 3.88 - 8.87 and the average was 83.5 - 212.8 mg/L.
β-d-Glucan Fluorescence HPLC Post-column derivatization

"Report Of 1997-BCOJ Collaborative Work. Determination Of High Molecular Weight β-glucan In Beer By Post-column Calcofluor Flow Injection Analysis"
J. Am. Soc. Brew. Chem. 1998 Volume 56, Issue 3 Pages 127-128
H. Maeba

Abstract: The collaborative work was carried out after setting up the HPLC system for the post-column Calcofluor flow injection analysis in each lab. (9) and confining the proper performance of the system in an anal. trial. Repeatability coefficients of variation for the determination of β-glucan in beer by flow injection ranged from 0.6 to 1.0% and were judged acceptable.
β-d-Glucan Fluorescence Post-column derivatization Standard method

"Relationships Among The β-glucan Contents Of Barley, Malt, Malt Congress Extract, And Beer"
J. Am. Soc. Brew. Chem. 1998 Volume 56, Issue 4 Pages 164-168
M. J. Edney, D. E. LaBerge, and D. E. Langrell

Abstract: Malting barley breeders have directed a sustained effort toward reducing β-glucan problems through selection of lines exhibiting low barley β-glucan content. This study determined β-glucan contents in barley, malt, and Congress ext. in an effort to define this relationship and to determine which best predicts levels obtained in beer. The impact of environment and genotype on this relationship and prediction was also considered. In total, 60 samples of barley and the corresponding malts, Congress fine-ground extracts, and beers were analyzed for β-glucan content using the Calcofluor-flow injection method of anal. β-Glucan contents of malt and Congress ext. were highly correlated with levels detected in the beer produced from those malts. The correlation between the β-glucan content of barley and beer was significantly lower. This study also demonstrated the strong influence of environmental growing conditions of the β-glucan contents of barley, malt, Congress ext., and beer, although the genetic component was also significant for malt, Congress extract, and beer.
β-Glucan Fluorescence

"Determination Of Biogenic Amines In Beers And Their Raw Materials By Ion-pair Liquid Chromatography With Post-column Derivatization"
J. AOAC Int. 1993 Volume 76, Issue 5 Pages 1027-1032
Izquierdo Pulido, M.L.;Vidal Carou, M.C.;Marine Font, A.

Abstract: Beer and wort were filtered and analyzed on a column (30 cm x 3.9 mm) of Nova-Pak C18 (4 µm) with gradient elution (1 ml/min) with (0.1 M sodium acetate/10 mM sodium octane sulfonate adjusted to pH 4.5)/methanol (9:1), and (0.2 M sodium acetate/10 mM sodium octane sulfonate adjusted to pH 4.5)/acetonitrile/methanol (35:12:3); the gradient program is tabulated. The eluate was mixed with a derivatizing agent (0.2 g of o-phthalaldehyde in methanol mixed with boric acid, KOH, water, 30% Brij-35 solution and mercaptoethanol) at a flow rate of 0.5 ml/min and the resulting fluorescence intensity was measured at 445 nm (excitation at 340 nm). The method was also used to analyze perchloric extracts of malts and hops; full details of the extraction procedure are given. The calibration graphs were rectilinear for 0.5-5 ml/l of histamine, β-phenylethylamine, tryptamine and spermidine, 1-5 mg/l of serotonin and spermine and 0.5-10 mg/l of agmatine cadaverine, putrescine, and tyramine. The detection limits (tabulated) ranged from 0.3-0.65 mg/l. Mean recoveries were 98-101.9% and within-day RSD (n = 6) were 1.8-10.7%.
Amines, biogenic HPIC Fluorescence Post-column derivatization

"Determination Of Total And Free Sulfite In Unstabilized Beer By Flow Injection Analysis"
J. AOAC Int. 1994 Volume 77, Issue 4 Pages 948-951
Bendtsen, A.B.;Jorgensen, S.S.

Abstract: AOAC methods previously described by Sullivan et al. (J. Assoc. Off. Anal. Chem., 1990, 73, 35 and 223) and adopted first action were modified for the analysis of unstabilized beer. The modifications included (i) stabilizing the sulfite standards with EDTA; (ii) changing the FIA manifold (diagram given) to decrease the dispersion; and (iii) using a non-linear calibration graph. The modifications were simple to implement and resulted in a more stable and accurate procedure. Results indicated that none of the beers exceeded the regulatory limit of 20 ppm of sulfide but some beers contained sulfite without declaring it.
Sulfite Standard method

"Merging Zones Standard Addition Technique For Determination Of Copper In Beer By Flow Injection Atomic Absorption Spectrophotometry"
J. AOAC Int. 1998 Volume 81, Issue 3 Pages 645-647
S&iacute;lvia M.V. Fernandes, Ant&oacute;nio O.S.S. Rangel and Jos&eacute; L.F.C. Lima

Abstract: A flow injection system for determination of copper in beer by atomic absorption spectrophotometry by the standard additions method is described. The manifold, based on the merging zone technique, prevents the burner head from clogging, as observed with the conventional reference method. With 5 standard additions, results are comparable with those of the reference method. Relative deviations were less than 5.8%, precision was better than 6.4%, and sampling rate was about 30 samples/h. A less precise, less accurate, but faster procedure (75 samples/h) is possible with only 2 standard additions. The detection limit was 5 µg/L.
Copper Spectrophotometry Standard additions calibration Merging zones Method comparison

"Titration Of Spoilt Beer Samples By Flow Injection Analysis"
J. Autom. Methods Manag. Chem. 1982 Volume 4, Issue 4 Pages 176-182

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

"Determination Of Total Carbon Dioxide In Beer And Soft Drinks By Gas Diffusion And Flow Injection Analysis"
J. Autom. Methods Manag. Chem. 1995 Volume 17, Issue 3 Pages 105-108

Abstract: Beer or carbonated soft drinks were made alkali by the addition of 10 M NaOH and a sample was injected into a carrier stream (1.2 ml/min) of water. The carrier stream merged with a reagent stream (1.2 ml/min) of 0.2 M H2SO4, passed through a mixing coil (30 cm x 0.7 mm i.d.) and went into a gas diffusion cell with bromocresol purple indicator solution as the acceptor solution. The absorbance was then read at 430 nm. Beer's law was obeyed up to 9 g/l of CO2. The CO2 contents of Tuborg and Pripps beer, coke and club soda are tabulated.
Carbon dioxide Spectrophotometry Gas diffusion

"Online Determination Of Ethanol In Bioprocesses Based On Sample Extraction By Continuous Pervaporation"
J. Biotechnol. 1993 Volume 31, Issue 3 Pages 317-325
I. Ogbomo*, A. Steffl, W. Schuhmann, U. Prinzing and H. -L. Schmidt

Abstract: The development of a flow injection analysis system (FIA) based on immobilized enzymes for the online determination of ethanol in biological liquids is presented. The FIA system includes prior to enzymatic analysis a continuous purification by pervaporation, which is supplemented with an electronically controlled temperature device. Fundamental experiments with the pervaporation module as well as the application of this system for the monitoring of ethanol in beer and during a bakers' yeast cultivation (measurable range 1-100 mM) are presented. The results show good reproducibility and satisfactory agreement with those of a common enzymatic test kit. Incorporation of the pervaporation module enhanced the stability of the enzyme noticeably.
Ethanol Sample preparation Immobilized enzyme Heated reaction Pervaporation Process monitoring Extraction

"Practical Applications Of Open Tubes In Liquid Chromatography"
J. High Resolut. Chromatogr. 1985 Volume 8, Issue 9 Pages 531-534
H. Engelhardt, B. Lillig

Abstract: The use of open tubes (0.12 to 0.6 mm i.d.) as columns and as post-column derivatization reactors is discussed. The advantages of knitted or stitched columns, to increase the radial mass transfer, are described and the theoretical background is discussed. Results are presented for the determination of amino-acids in the pg range with use of a knitted open-tube reactor (10 m x 0.34 mm) and phthalaldehyde for derivatization. The chromatogram of the free amino-acids in beer is shown.
Amino Acids HPLC Spectrophotometry Open tubular reactor Post-column derivatization Theory Knotted reactor

"Modified Fluorimetric Flow Injection Analysis Method For The Determination Of (1->3)(1->4)-β-D-glucan"
J. Inst. Brew. 1987 Volume 93, Issue 5 Pages 396-398
Erika Mekis, Gy&ouml;rgy Pint&eacute;r, Gy&ouml;rgy B&eacute;ndek

Abstract: Aqueous solution of barley β-glucans are analyzed by a modification of the method of Joergensen et al. (Proc. 20th Congr. Eur. Brew. Conv., 1985, 403). The method involves use of the fluorescent dye Calcofluor as specific reagent for (1->3)(1->4)-β-D-linkages. The single-line system used involves only one pump, sample solution being directly injected into the reagent stream. The reaction gives increased intensity of fluorescence, which is detected at 420 nm (excitation at 366 nm) by a flow-through-cell fluorimeter. Analysis takes 20 s.
β-d-Glucan Fluorescence Optimization

"Fractionation Of Small Peptides From Beer"
J. Inst. Brew. 1989 Volume 95, Issue 1 Pages 35-41
C. J. Dale, T. W. Young

Abstract: Small peptides (mol. wt. 1000) were isolated from beer by hollow-fiber ultrafiltration and separated by LC on a column (92 cm x 2.6 cm) of Sephadex LH 20 followed by another (36 cm x 1.6 cm) of Sephadex G10, with 0.3 M Na acetate (pH 4.0) as eluent. Fractions were analyzed by HPLC on a column of Vydac C18, with gradient elution (1.5 mL min-1) with 0 to 60% of acetonitrile in 0.05% trifluoriacetic acid (details given) and detection at 220 or 260 nm. After hydrolysis of small peptide fractions with HCl, the amino-acid composition was determined by HPLC on an Aminex A8 column with gradient elution using sodium citrate buffer, and post-column derivatization with ninhydrin.
Peptides HPLC Spectrophotometry Post-column derivatization

"Determination Of β-glucan In Wort And Beer By Its Binding With Calcofluor, Using A Fluorimetric Flow Injection Analysis Method"
J. Inst. Brew. 1989 Volume 95, Issue 5 Pages 327-332
Jos&eacute; M. Sendra1, Jos&eacute; V. Carbonell, Maria J. Gosalbes, Victoria Todo

Abstract: Previous fluorimetric methods for determination of β-glucan in worts and beers were studied and modified to improve their performance. Fluorescence was measured at 425 nm (excitation at 338 nm). By increasing the I of the carrier solution (by adding 1% of NaCl), the mol. wt. range of β-glucans which were effectively bound by calcofluor was increased. Low-mol.-wt. components of beer had no effect on the analysis. Recommendations are presented to overcome the interference caused by the color of wort and beer. Results are presented for 36 beers, and the possible use of the method to detect addition of exogenous β-glucanases is discussed.
β-Glucan Fluorescence Interferences

"Several New Factors Influencing The Measurement Of β-glucan Content Using Calcofluor Flow Injection Analysis Method"
J. Inst. Brew. 1995 Volume 101, Issue 5 Pages 371-374
Izawa, By Masayuki; Takashio, Masachika; Koshino, Shohei

Abstract: Factors such as temperature, calcofluor concentration, sample injection volume, void volume of the mixing tube and other factors have been reported to influence the calcofluor flow-injection analysis (FIA) of β-glucan. In addition to these factors, we revealed the following factors and elucidated their effects on the FIA of β-glucans: the inside diameter and arrangement of the mixing tube, calibration method using peak area or peak height of the edition patterns, and the quality of the calcofluor reagent. An apparently lower value was obtained when (1) the mixing tube had a smaller inside diameter, (2) the mixing tube was looped in a ring of smaller diameter, or (3) the mixing tube was wound as double coils in a figure eight instead of a loop. Furthermore, it was indicated that the peak area calibration produced higher measures values than the peak height calibration. The reagent also affected the results; a calcofluor reagent from Sigma Chemical Co. gave a higher value than one from Polyscience Inc. It was concluded that these troublesome phenomena were derived from the difference between the test sample and the standard solution of β-glucan, that is, the molecular weight distribution of β-glucans and/or the sugar and ethanol in the sample solutions. Based on these findings, it is suggested that international standardization of the FIA method for β-glucan be made.
β-d-Glucan Fluorescence Optimization Temperature

"Inhibitor Of Fluorescence Reactions Between Calcofluor And β-(1,3)(1,4)-d-glucan In Beer And Wort"
J. Inst. Brew. 1996 Volume 102, Issue 2 Pages 87-91
Masayuki Izawa, Masachika Takashio, Teruo Tamaki

Abstract: An inhibitor of calcofluor fluorescence reaction in beer and wort was shown by analyzing beers and worts containing no β-glucan. The inhibitory activity was enhanced against the fluorescence reaction which is intensified by linkage of calcofluor with β-glucan compared to the fluorescence of calcofluor itself. The investigation indicated that the inhibitor was derived from malt and is produced during the germination process. The inhibitory activity in beer and wort changed with the degree of malt modification and the ratio of malt in the grist. Japanese beers had a wide range of inhibitory activities against the calcofluor fluorescence. lowering the apparent β-glucan contents by 12 to 20%. The inhibitor in beer and wort appeared to be an acidic compound with a molecular weight of less than 1000 daltons.
β-Glucan Fluorescence Quenching

"Determination Of High Molecular Weight β-glucan In Wort And Beer Using A Post-column Calcofluor Flow Injection Analysis (FIA) Method"
J. Inst. Brew. 1996 Volume 102, Issue 3 Pages 183-189
Masayuki Izawa, Masachika Takashio, Teruo Tamaki

Abstract: A post-column FIA system was devised to determine β-glucan content in malt wort and beer samples. The FIA system consisted of a LC-6A pump, SIL-6A injector, CR-3A integrator, RF-535 fluorimeter and an SCL-6A system controller (Schimadzu Seisakusho Co.) Operating conditions are tabulated. Samples (5 µL) were applied to a polyhydroxymethacrylate column (5 cm x 6 mm) with an exclusion limit of 100 000 daltons. The eluate was mixed with Calcofluor reagent (calcofluor/Triton x 100 (1:5) in 0.1 M Tris buffer of pH 8.2) at a flow rate of 2 ml/min. Detection was at 420 nm (excitation at 360 nm). This technique allowed the rapid and specific measurement of high mol wt. Beta-glucan in a few minutes. Calibration graphs were linear up to 300 mg/l Beta-glucan; RSD were from 0.8-1.5% (n = 9). Results correlated well with those obtained by the standard enzymatic method.
β-Glucan Fluorescence Method comparison Triton X Post-column derivatization Surfactant

"Determination Of Total Sulfur Dioxide In Beer By Flow Injection Spectrophotometry Using Gas-diffusion And The Merging Zones Technique"
J. Inst. Brew. 1998 Volume 104, Issue 4 Pages 203-205
S&iacute;lvia M. V. Firnandes, Antonio O. S. S. Rangel, Jos&eacute; L. F. C. Lima

Abstract: A flow injection system for the determination of total sulfur dioxide in beer is described. The methodology involves the same colorimetric reaction of the reference method between SO2, p-rosaniline and formaldehyde. The sample is introduced into the manifold without previous pretreatment, the hydrolysis process, isolation of the SO2 from the matrix and the colorimetric reaction, being carried out inside the flow tubes. To isolate the SO2, a gas-diffusion unit was included in the system and to minimize p-rosaniline consumption, a merging zones technique was used. The results obtained were in good agreement with a reference method (relative deviations lower than 5%), the precision being better than 2.5% (relative standard deviation). A sampling-rate of 30 samples per h was obtained and the consumption of p-rosaniline was reduced 10 fold when compared to the reference method.
Sulfur dioxide Spectrophotometry Gas diffusion Merging zones Method comparison

"Analysis And Significance Of High-molecular-weight β-glucans In Beer"
Monatsschr. Brauwiss. 1988 Volume 41, Issue 10 Pages 384-395
Wagner, N., Esser, K. D., und Kr&uuml;ger, E.

Abstract: Methods evaluated for the determination of β-glucans were:(I) flow injection analysis, as described by Joergensen (Proc. Congr. - Eur. Brew. Conv., 1985, p. 403);(II) the enzymatic method of McCleary and Glennie-Holmes (cf. Anal. Abstr., 1986, 48, 3F62) with use of Biocon reagents; and (iii) a modified enzymatic method [without (NH4)2SO4 precipitation] for total β-glucan content. Method(I) proved the most suitable for determining the β-glucans that are retained by kieselguhr and thus impede the filtration of beer. The effects of different mol. size fractions of β-glucans on filterability of beer were examined.
β-d-Glucan Method comparison

"EBC Methods For Determination Of High-molecular-weight β-glucan In Barley, Malt, Wort And Beer"
Monatsschr. Brauwiss. 1989 Volume 42, Issue 4 Pages 162-166
Munck, L., Jorgensen, K.G., Ruud-Hansen, J., und Hansen, K.T.

Abstract: Two methods were evaluated in a collaborative test with 14 participating laboratories. The methods were; (i) that described by, e.g., Joergensen (Carlsberg Res. Commun., 1988, 53, 277), involving flow injection analysis with fluorimetric detection by using the fluorichrome Calcofluor, which binds specifically to β-glucan; and (ii) that described by, e.g., McCleary and Nurthen (J. Inst. Brew., 1986, 92, 168), involving enzymatic hydrolysis. Barley, malt and beer samples were analyzed for six concentration. of β-glucan. Acceptable levels of repeatability and reproducibility were achieved for both methods in the collaborative test and results for the two methods correlated well. Both methods are accepted by the Analytical Committee as Standard Methods.
β-Glucan Fluorescence Standard method Method comparison

"Application Of Continuous-flow Analysis Technology For Quality Control In The Brewing Industry. 1. Use Of Continuous-flow Analysis Technology In Brewery Analysis"
Monatsschr. Brauwiss. 1992 Volume 45, Issue 3 Pages 76-78
Baier, B., J&ouml;dicke, T., L&uuml;ck, M., M&uuml;ke, O., Harms, J., und Kr&uuml;ger, E.

Abstract: A brief description is given of the principles of segmented-flow analysis and flow injection analysis, and possibilities for their application in quality control in the brewing industry are discussed. In the brewing industry, analytical methods are still largely manual and the scope for the replacement of these time-consuming methods will be shown in future articles. (8 references).
Review Process control

"Application Of Continuous-flow Analysis Technology For Quality Control In The Brewing Industry. 2. Determination Of Anthocyanogen In Wort And Beer With The Skalar Continuous-flow Analyser"
Monatsschr. Brauwiss. 1992 Volume 45, Issue 4 Pages 116-121
Baier, B., J&ouml;dicke, T., L&uuml;ck, M., M&uuml;ke, O., Harms, J., und Kr&uuml;ger, E.

Abstract: Wort or beer was analyzed with use of the Skalar Continuous-flow Analyser. The sample was mixed with water, sodium disulfite solution and sodium molybdate solution and the absorbance was measured at 420 nm. The coefficient of variation was 0.44 to 3.88%. The results compared well with those of MEBAK (methodensammlung der mitteleuropaeischen brautechnischen Analysenkommission). The continuous-flow process resulted in reduction in personnel work time and reduced energy and chemical costs.
Anthocyanogens Spectrophotometry Process control Method comparison

"Application Of Continuous-flow Analysis Technology For Quality Control In The Brewing Industry. 3. Continuous-flow Analysis In The Determination Of The Total Polyphenol Content In Wort And Beer"
Monatsschr. Brauwiss. 1992 Volume 45, Issue 6 Pages 204-210
Baier, B., J&ouml;dicke, T., Harms, J., L&uuml;ck, M., M&uuml;ke, O., und Kr&uuml;ger, E.

Abstract: The non-specific reaction of phenols with Fe(III) in NH3 medium was applied to the determination of the total polyphenols in beer and wort using a continuous-flow analyzer. (Skalar Analytic, Erkelenz, Germany), measuring the absorbance at 620 nm vs. a reagent blank. Results compared well to the standard EBC method. Use of the analyzer. enabled cost savings and better reproducibilities to be obtained.
Polyphenol Spectrophotometry Method comparison Process control

"Evaluation Of The Dissolving Properties Of Malts Using The Friabilimeter, Calcofluoride And FIA Method"
Monatsschr. Brauwiss. 1996 Volume 49, Issue 7-8 Pages 220-225
Wackerbauer, K., Hardt, R., Hirse, U.

Abstract: This article describes the most common methods for the determination of the cytolytic dissolving of brewing malts in current usage. On the basis of malting tests and the study of trade malts, the authors assess the information provided from the friabilimeter and calcofluoride method and the determination of beta glucanes in the congress wort using flow injection. The benefits and drawbacks of the various methods are compared.

"An Update Of Analytical Procedures For The Determination Of Malt Modification And Malt Homogeneity. 4"
Monatsschr. Brauwiss. 1997 Volume 50, Issue 1-2 Pages 49-57
Moll, M.

Abstract: More than 40 different methods of analysis allowing the evaluation of malt modification and 4 methods for homogeneity have been described (part 1 to 4) with their strengths and weaknesses and their limits. A perspicacious brewer should be able to make the best choice from these methods of analysis with the objective of predicting malt behavior during the brewing process. Ancestral methods, nearly centenarian, must be revised at an international level. The accumulation of analytical methods in malt specifications should be avoided for economical reasons and to avoid overlapping. 291 References

"Experiments On The Enzymatic Online Determination Of Diacetyl And 2-acetolactate In Beer"
Monatsschr. Brauwiss. 1997 Volume 50, Issue 5-6 Pages 108-113
Ogbomo, I., Becker, T., Hummel, W., Danzer, J. und Schmidt, H.-L.

Abstract: In regard to an automated and continuous control of beer ripening: a flow injection analysis (FIA) system with immobilized enzymes has been conceived and tested. As to the enzymatic determination of free and total diacetyl using NADH fluorescence it turned out that none of the three available ''diacetyl reductases'' had a sufficient specificity, all of them reducing in addition 2,3-pentanedione and acetoine. The dicetones could be preseparated from the latter compound by continuous pervaporation, and in the pervaporate satisfactory results of diacetyl determination could be obtained, provided the concentration of acetoine in the primary analyte solution was below 8 ppm. The reaction time for the oxidative decarboxylation of 2-aceto-lactate to diacetyl could be reduced from 60 min. at 90°C to 2 min. at 25°C, using Fe3+ as oxidant; this would permit to integrate a corresponding conversion device in a FIA-system for the analysis of ''total diacetyl''. As an alternative for the enzymatic determination of 2-acetolactate the reductive isomerization of this compound was tested. The corresponding enzyme from enterobacter aerogenes catalyzed the conversion of the subtrate, but also of its homologue 2-aceto-2-hydroxybutyrate. Nevertheless the determination of 2-acetolactate was possible in batch systems, however, in an online FIA-system with immobilized enzyme the sensitivity of the enzyme (K-m for acetolactate = 0.45 mM) did not meet the demands needed for the problem in question. The potential of screening or genetic engineering for the provision of more selective and sensitive enzymes is discussed. 21 References
Diacetyl 2-Acetolactate Fluorescence Immobilized enzyme Interferences Pervaporation

"Immobilisation And Characterisation Of Phenylethanol Dehydrogenase From Lactobacillus Kefir And Its Application In A Flow Injection Analysis System"
Process Biochem. 1995 Volume 30, Issue 1 Pages 49-55
Leman Tarhan*, Werner Hummel

Abstract: Phenylethanol dehydrogenase was isolated from Lactobacillus kefir, and some kinetic parameters and properties of native and immobilized phenylethanol dehydrogenase on modified DEAE-Cellulose, Bioran, Mobitec, and VA-epoxy were investigated. The activity of immobilized phenylethanol dehydrogenase was examined in a flow injection analysis system in relation to the concentration of diacetyl in water and beer.
Diacetyl Immobilized enzyme Kinetic

"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

"Ethanol Determination By Flow Injection Analysis With Chemiluminescence Detection"
Rev. Chim. 1997 Volume 48, Issue 8 Pages 726-731
Danet, A.F.;Badea, M.;Jipa, S.

Abstract: A highly sensitive flow injection system was developed for ethanol determination in beer sample. The system is based on the oxidation of ethanol in the presence of alcohol oxidase(AOD). The concentration of the hydrogen peroxide produced was determined by luminol chemiluminescence. The determination range was 0.01-0.1%(v/v). The throughput was 30 samples per hour. From the tested substances, only L-cysteine generated a signal comparable with that of ethanol, but this interference can be completely avoided by prior complexing with Cu2+ ions. For lower concentrations of ethanol we used stopping-flow method.
Ethanol Chemiluminescence Interferences Stopped-flow

"A Rapid And Accurate Determination Of Ethanol Using And Oxidase-electrode In A Flow Injection System"
Z. Lebensm. Unters. Forsch. 1983 Volume 177, Issue 5 Pages 356-358
Anita Schelter-Graf, Horst Huck und Hanns-Ludwig Schmidt

Abstract: A layer of cigarette paper impregnated with a 20% solution of alcohol oxidase in Tris buffer solution was applied to a Clark O electrode, and the apparatus was covered with a dialysis membrane. The electrode was included in a flow system comprising a container for the buffer solution (0.2 M Tris containing 0.1% of NaN3; pH 7.5), a pump, an injector, the electrode (at 25°C), an amplifier and a recorder. The response of the electrode is rectilinear for up to 100 mM ethanol. Results for determination of ethanol in beer (diluted 10-fold and de-carbonated) agreed well with those obtained by refractometric analysis, showing that other beer constituents that are substrates for alcohol oxidase, viz, ethanol, formaldehyde, acetaldehyde, Na formate, acetate, propionate and butanol, did not interfere when present in normal amounts.
Ethanol Amperometry Electrode Interferences Dialysis Enzyme

"Sequential Injection Spectrophotometric Determination Of Orthophosphate In Beverages, Wastewaters And Urine Samples By Electrogeneration Of Molybdenum Blue Using Tubular Flow-through Electrodes"
Anal. Chim. Acta 2004 Volume 510, Issue 1 Pages 61-68
Francisca Mas-Torres, Jos&eacute; Manuel Estela, Manuel Mir&oacute;, Andreu Cladera and V&iacute;ctor Cerd&agrave;

Abstract: A novel and automated sequential injection procedure is proposed for the spectrophotometric determination of orthophosphate without requiring unstable chemical reducing species used in the classical molybdenum blue method. The flowing methodology is based on the on-line generation of the detectable species by electrochemical reduction of the 12-molybdophosphoric acid complex using a stainless steel tubular flow-through working electrode. The established method is linear up to 20 mg/l P, with coefficients of variation (n=10) of 2.4 and 1.8% for 2.0 and 10 mg/l P, respectively. The versatility of the sequential injection method to analyze samples containing high orthophosphate levels has been demonstrated by the implementation of a dilution chamber as well as flow-reversal techniques, yielding relative standard deviations (n=17) better than 2.0% for standards containing 200 and 800 mg/l P. The proposed analyzer. features an extremely wide dynamic range (viz., 0.3-800 mg/l) as well as improved tolerance to silicate interference, so that Si/P ratios higher than 50 are tolerated at the 5% level. Electrochemical conditions, reagent concentrations and physical variables have been thoroughly investigated. The method has been applied to the determination of orthophosphate in wastewaters as well as beverages and biological samples containing high concentrations of the target analyte. The t-test comparison of the means for the developed sequential injection system with electroreduction and both the molybdenum blue classical spectrophotometric batch procedure and inductively coupled plasma-optical emission spectrometric detection selected as external reference methods revealed that there is no evidence of significant differences between the obtained results at the 95% confidence level.
Phosphate Spectrophotometry Sequential injection Method comparison Interferences Flow reversal Gradient technique Mixing chamber Electrochemical reagent generation

"β-Glucan In Congress Wort By Fluorescence Method"
J. Am. Soc. Brew. Chem. 1991 Volume 49, Issue 4 Pages 187-189
J. Cuti; S. Bock; T. Day; M. Izawa; B. Jones; W. Ladish; R. Lewandowski; S. Lie (EBC); S. Lisbjerg; M. Munar; M. Rehmanji; H. Wagner; and D. Thomas

Abstract: The fluorescence method for b-glucan in congress wort showed high repeatability and reproducibility coefficients. of variation and is considered acceptable.
β-Glucan Fluorescence

"Coordination Of New And Alternate Methods Of Analysis"
J. Am. Soc. Brew. Chem. 1997 Volume 55, Issue 4 Pages 168-169
J. Miller

Abstract: Standard methods report
Phenols, poly

"Bitterness In Beer By Automated Flow Analysis"
J. Am. Soc. Brew. Chem. 1994 Volume 52, Issue 4 Pages 182-183
T. Hassinger; D. Cattanach; J. Gearhart; C. McLinn; M. Ono; T. Otterson; S. Sakuma; J. Swims; and J. Murphey

Abstract: This subcommittee was established to evaluate the AFA method for determining beer bitterness (2,3) as an alternative to the manual ASBC Method Beer-23.
Bittering compounds Method comparison

"α-Amylase In Malt By Automated Flow Analysis"
J. Am. Soc. Brew. Chem. 1999 Volume 57, Issue 4 Pages 175-176
G. Laycock

Abstract: In its fifth year, the subcommittee was charged with evaluation of the AFA procedure for the measurement of a-amylase, including the use of a calibration standard with a higher a-amylase value to address inconsistencies with malt of higher levels. At the 1998 Annual Meeting in Boston, MA, the subcommittee recommended that a decision regarding possible approval of the AFA method be delayed until after a more extensive evaluation of the data generated in the fifth year and subsequent discussion by the subcommittee at the 1999 Annual Meeting in Phoenix, AZ (2).
α-Amylase Method comparison

"α-Amylase In Malt By Automated Flow Analysis"
J. Am. Soc. Brew. Chem. 1998 Volume 56, Issue 4 Pages 183-184
G. Laycock

Abstract: This was the fifth year for this subcommittee charged with evaluation of automated flow analysis (AFA) procedures for the measurement of a-amylase. In the fourth year (2), the subcommittee found that the AFA method rendered acceptable repeatability coefficients of variation but unacceptable reproducibility coefficients of variation and recommended repeating the collaborative using a calibration standard with a higher a-amylase value to address inconsistencies with malts of higher levels.
α-Amylase Method comparison

"α-Amylase And Diastatic Power In Malt By Automated Flow Analysis"
J. Am. Soc. Brew. Chem. 1997 Volume 55, Issue 4 Pages 199-202
G. Laycock

Abstract: This was the fourth year for this subcommittee to evaluate diastatic power (DP) and a-amylase by automated flow analysis (AFA). In the third year (3), the subcommittee found that for DP and a-amylase, AFA gave acceptable repeatability and reproducibility coefficients of variation. The subcommittee evaluation was repeated as a result of differences in the DP value for the standard malt between the chairman's lab and the collaborators' laboratories. The difference resulted in recalculation of the DP data. In its second year (4), AFA gave acceptable repeatability and reproducibility coefficients of variation. However, DP means by AFA differed significantly from those by the standard reference method. For a-amylase, AFA gave acceptable repeatability coefficients of variation but unacceptable reproducibility coefficients of variation. In its first year, AFA gave acceptable repeatability and unacceptable reproducibility coefficients of variation for both a-amylase and DP (5).