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 -> non alcoholic -> fruit

Citations 15

"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

"Study Of A Nickel-catalysed Glassy Carbon Electrode For Detection Of Carbohydrates In Liquid Chromatography And Flow Injection Analysis"
Anal. Chim. Acta 1991 Volume 248, Issue 1 Pages 117-125
I. G. Casella, E. Desimoni and T. R. I. Cataldi

Abstract: The electrochemical sensor was prepared by deposition of Ni from its nitrate solution on to a glassy carbon electrode. The electrode was dried in air at 35°C for 30 min, washed with water and conditioned for 2 h in 0.2 M NaOH solution with cycling between 0 and 0.8 V vs. Ag/AgCl. The electrode surface was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements with glucose. The peak currents were related to carbohydrate concentration. and scan rate, and in flow injection analysis measurements the peak area was inversely related to the flow rate. The sensor was applied to the carbohydrate LC analysis of milk and pear juice (both diluted 1000-fold with 0.2 M NaOH). It showed good background current stability, catalytic activity, detection limits and reproducibility.
Carbohydrates LC Electrode Electrode

"Study Of The Influence Of Ordered Media On The Determination Of Lead By Hydride-generation Inductively Coupled Plasma Atomic-emission Spectrometry"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 175-182
M. C. Valdés-Hevia y Temprano, B. Aizpún Fernández, M. R. Fernández de la Campa and A. Sanz-Medel*

Abstract: Several micelle- and vesicle-forming substances were examined for use in the continuous-flow generation of plumbane. The best results were obtained with hexadecyltrimethylammonium bromide (I) micelles and didodecyldimethylammonium bromide (II) vesicles. For the analyzes, the test solution (containing 0.1 mM I or 1 mM II), 2% HNO3 and aqueous 6% ammonium thiosulfate were merged in a four-channel union cross and the resulting solution was merged with 10% NaBH4 solution in aqueous 0.1% NaOH before passing to the grid nebulizer of an ICP spectrometer with a 40 MHz source unit. Best results were obtained with the I-containing system; the detection limit was 9 ng/ml and the RSD (n = 50) was 1.4% at 50 ng/ml. Interference studies for a range of elements and anions showed that Se, As, Hg and Sn were less troublesome in the presence of I. The method was applied to the determination of Pb in commercial apple, orange and pineapple juices without pre-treatment.
Lead Spectrophotometry Micelle Interferences

"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

"Simultaneous Quantitation Of Citrate And Isocitrate In Citrus Juice By A Flow Injection Method Based On The Use Of Enzyme Reactors"
Anal. Chim. Acta 1996 Volume 321, Issue 2-3 Pages 157-164
Kiyoshi Matsumoto* and Tadayuki Tsukatani

Abstract: A dual channel FIA manifold with amperometric detection was described for the simultaneous determination of citrate and isocitrate in citrus juices. The channel for citrate determination consisted of a co-immobilized citrate lyase/oxaloacetate decarboxylase reactor followed by a pyruvate oxidase reactor. The generated H2O2 was monitored amperometrically. A carrier stream (0.85 ml/min) of 0.1 M phosphate buffer of pH 7.5 containing 10 mM MgCl2, 80 µM-thiamine pyrophosphate and 10 µM-FAD was used. The channel for isocitrate determination consisted of a NADP-specific isocitrate dehydrogenase reactor and the generated NADPH was monitored amperometrically. A carrier stream (1 ml/min) of 50 mM phosphate buffer of pH 6.5 containing 20 mM MgCl2 was used. The sample and coenzyme (1 mM NADP) were injected using a sandwich method with loops of 80 µL for each solution. The Pt working electrode was set at +0.6V (for H2O2) or +0.75 V (for NADPH) vs. Ag/AgCl. Linear calibration graphs were obtained for 0.25-5 mM citrate and 2.5-50 µM-isocitrate and RSD (n = 10) were 2% for 5 mM citrate and 50 µM-isocitrate. The results were confirmed using F-kits (enzymatic-spectrophotometric methods).
Citrate Isocitric acid Amperometry

"Determination Of L-asparagine Using Flow Injection Systems With Spectrophotometric And Potentiometric Detection"
Anal. Chim. Acta 1996 Volume 336, Issue 1-3 Pages 113-122
Kathrin Stein*, Renbing Shi and Georg Schwedt

Abstract: Two FIA methods were developed for determining asparagine in foods. The first method was based on the catalyzed hydrolysis of asparagine by immobilized asparaginase to yield NH3. The NH3 diffused through a PTFE membrane and was detected (i) spectrophotometrically using an acid-base indicator solution as the acceptor or (ii) potentiometrically using a pH electrode and water as the acceptor. The linear ranges and RSD (n = 5) were 0.2-2.3 mM and 1.7% (at 0.75 mM asparagine), respectively, for spectrophotometric detection and 0.1-4 mM and 2.5% (at 1 mM asparagine), respectively, for potentiometric detection. The sampling frequency was 35/h. The second method used a biosensor fabricated by attaching a membrane with immobilized asparaginase on to a pH electrode. The linear range and RSD (n = 5) of this method were 0.1-2 mM and 2.3% (at 1 mM asparagine), respectively. The sampling frequency was 30/h. The methods were applied to apple and orange juice, oranges and asparagus. The sample preparation procedure involved diluting the fruit juices or filtering the homogenates of the solid foods. Recoveries of 50 mg/l or 50 mg/100 g asparagine from spiked foods were >94.3%.
l-asparagine Potentiometry Electrode Spectrophotometry Sensor Immobilized enzyme Teflon membrane Gas diffusion

"Direct Chemiluminescence Determination Of Ascorbic-acid Using Flow Injection Analysis"
Anal. Chim. Acta 1997 Volume 356, Issue 2-3 Pages 289-294
Irena B. Agater and Roger A. Jewsbury*

Abstract: A flow injection method is described for the determination of (5 x 10^-7 to 1 x 10^-3 M) ascorbic acid by measurement of the chemiluminescence from direct oxidation with permanganate in an acidic medium. The method is applied to fruit drinks and nutritional supplements and compared satisfactorily with titrimetric and spectrofluorimetric methods. 14 References
Ascorbic acid Chemiluminescence Method comparison

"Determination Of Ascorbic Acid By Flow Injection With Chemiluminescence Detection"
Analyst 1993 Volume 118, Issue 6 Pages 639-642
Abdulrahman A. Alwarthan

Abstract: Flow injection and chemiluminescence detection were used to determine 30 amol of ascorbic acid based on the reducing effect of ascorbic acid on Fe(III) and measuring the Fe(II)-catalyzed light emission from luminol oxidation by H2O2. The method was used to determine ascorbic acid levels in tablets, capsules, syrup and fruit juices. The flow cell was a coil made of 1.3 mm i.d. glass tubing spiralled to a diameter of 35-mm. The photomultiplier tube was operated at 400 V. The acidified Fe(III) solution was used as the carrier stream for the sample which was acidified with 1% metaphosphoric acid. The luminol was mixed with the carrier solution at the reaction coil. Each solution was pumped (2.03 mL min-1) by a peristaltic pump. The calibration plot was rectilinear from 10 pM to 100 nM ascorbic acid. The detection limit was 30 amol. The coefficient of variation (n = 10) was 1.4% (for an injection of 1 µM). Recoveries ranged from 90.8 to 101.1% and 95.5 to 106.4% for pharmaceutical preparations and fruit juices, respectively.
Ascorbic acid Chemiluminescence

"Determination Of Aluminum In Slurry And Liquid Phase Of Juices By Flow Injection Analysis - Graphite-furnace Atomic Absorption Spectrometry"
Anal. Chem. 1993 Volume 65, Issue 22 Pages 3331-3335
Marco A. Z. Arruda, Mercedes Gallego, and Miguel Valcarcel

Abstract: A flow system is illustrated by which juice samples were diluted 20-fold with 0.2% HNO3, or filtered through paper and then diluted, mixed online with 10 mM Mg(NO3)2 as matrix modifier, and then loaded into autosampler cups for analysis by AAS with use of pyrolytic graphite tubes with L'vov platforms. The system was applied to commercial fruit juices; aqueous standard solution were used for calibration. The RSD for 2-20 µg/l of Al in aqueous standards was 7.0% (n = 20), compared with 8.2% for conventional AAS. A study investigated the performance of several automated slurry sample introduction flow injection (FI) systems for the determination of aluminum in fruit and tomato juices by a combined FI graphite furnace atomic absorption spectrometry technique. These systems do not require a thixotropic agent or magnetic stirring bar, vortex mixing, gas bubbling, or ultrasonic agitation prior to injection into a graphite furnace. One of the FI systems assayed yielded information about the analyte distribution in the solid and liquid phases of the slurry as the difference between the aluminum content in the slurry and filtrate, thereby exploiting the full potential of this combined technique.
Aluminum Spectrophotometry Slurry

"Determination Of Titratable Acidity And Ascorbic Acid In Fruit Juices In Continuous-flow Systems"
Fresenius J. Anal. Chem. 1993 Volume 347, Issue 6-7 Pages 293-298
J. M. Alamo, A. Maquieira, R. Puchades and S. Sagrado

Abstract: Total acidity and ascorbic acid concentration. were rapidly measured by FIA (manifolds illustrated) for several fruit juices, and the results were compared with those obtained by titrimetry. Total acidity was measured by passing the sample through a dialysis cell, collecting the dialysate in water and injecting portions (290 µL) of the resulting solution into a stream of water that was then merged with a stream of buffered bromothymol blue solution After passage through a 50 cm reaction coil the absorbance was measured at 616 nm. Ascorbic acid was determined by passing the sample through a dialysis cell, collecting the dialysate in 0.01 M FeCl3 in 5 mM H3PO4 and injecting portions (210 µL) into a stream of 0.01 M 1,10-phenanthroline in 4 mM acetate buffer of pH 4.5. After passage through a 100 cm reaction coil the absorbance was measured at 510 nm. Individual acids were determined semi-quantitatively by collecting the dialysate in water and analyzing portions (120 µL) of the solution on a Spherisorb C8 column (12 cm x 0.4 mm) with detection at 210 nm.
Acidity Ascorbic acid Spectrophotometry Dialysis

"Flow Injection Analysis Of Glucose By Fibre-optic Chemiluminescence Measurement"
Anal. Lett. 1993 Volume 26, Issue 7 Pages 1493-1503
Suleiman, A.A.;Villarta, R.L.;Guilbault, G.G.

Abstract: The cited system consisted of a reagent stream (0.3 ml/min) of 1 mM luminol in 25 mM Na2CO3, which was merged with a second stream of 10 mM K3Fe(CN)6. The sample stream (0.3 ml/min) consisted of 50 mM acetate buffer of pH 5.6 and was passed over a column of immobilized glucose oxidase reactor, which oxidized the glucose present in the sample to gluconic acid and H2O2. The latter was transported by the sample stream to a flow cell, where it reacted with the mixed reagent stream. The resulting chemiluminescence was passed through an optical bundle to a detector and recorded. The calibration graph was rectilinear for 0.25-2.5 mM with an RSD of 5%. The cited method was applied to the determination of glucose in baby fruit juices. Results agreed well with those obtained by official AOAC methods. No interferences were observed by the presence of fructose, ascorbic acid, citric acid and other polysaccharides.
Glucose Chemiluminescence Optical fiber Immobilized enzyme Interferences

"Electro-oxidation Of Ascorbic Acid On The Dispersed-platinum Glassy-carbon Electrode And Its Amperometric Determination In Flow Injection Analysis"
Electroanalysis 1996 Volume 8, Issue 2 Pages 128-134
Innocenzo G. Casella *

Abstract: The electrode was prepared by depositing a solution (10 µL) of 30 mM PtCl4 onto the surface of a polished vitreous C electrode. The electrode was dried at 40°C for 30 min and conditioned for 1 h in 50 mM HClO4 using cyclic voltammetry between -0.3 and 1.3 V vs. SCE; a Pt foil electrode was used as counter electrode. Voltammograms were again recorded after addition of 20 mM ascorbic acid (I) in the supporting electrolyte. Response was linear up to 100 mM I. The effects of scan rate and pH of the supporting electrolyte were investigated and reported. The sensor was used in a FIA system using an applied potential of 0.6 V. The effects of flow-rate of the carrier solution and presence of foreign species were reported. Results obtained for samples of fruit juices were in good agreement with those obtained by HPLC methods. Recoveries were >99%.
Ascorbic acid Amperometry Electrode Voltammetry

"Simple And Rapid Determination Of L-ascorbic Acid By Flow Injection Analysis With Spectrophotometric Detection"
Bunseki Kagaku 1987 Volume 36, Issue 10 Pages 625-628
Yamane, T.;Ogawa, T.

Abstract: The cited method is based on the reduction of Fe(III) to Fe(II) by using ascorbic acid(I) and subsequent formation of a Fe(II) complex with 1,10-phenanthroline, which is monitored spectrophotometrically at 510 nm. The calibration graph was rectilinear for up to 10 µM-I when 50 µM-Fe(III) and 0.25 mM 1,10-phenanthroline were successively mixed with sample solution at 0.55 and 0.25 mL min-1, respectively. A 0.1 mL sample was initially injected into water as carrier stream. For 5 µM-I, the coefficient of variation was 1.8%. The method was applied to the determination of I in fresh fruit juices and fruit drinks; results obtained were compared with those obtained by using a titrimetric method involving 2,6-dichlorophenolindophenol.
Ascorbic acid Spectrophotometry Method comparison

"Biosensors In Automated Analysis Systems. 2. Fructose Determination In Juices By Fructose Dehydrogenase Thick-film Platinum Electrodes"
Dtsch. Lebensm. Rundsch. 1996 Volume 92, Issue 2 Pages 35-39

Abstract: Fructose was determined amperometrically with a ring-disc electrode of alumina ceramic coated with Pt paste containing immobilized fructose dehydrogenase and BSA. The Pt ring was the reference electrode and the injection needle was the counter electrode. The working electrode was fitted into a Plexiglas flow-through wall-jet cell. The system was used in FIA, flow diffusion analysis and HPLC. Fruit juice was diluted 1:100 (and filtered, for FIA or HPLC). For FIA, the sample was first passed through an ascorbate oxidase reactor to remove ascorbic acid. The FIA flow stream or flow diffusion acceptor stream was 0.15 M McIlvaine buffer of pH 5, containing 5 mM potassium ferricyanide as mediator and detection was at 390 mV. For HPLC, a 5 µm Supelcosil LC-18 column (25 cm x 4.6 mm i.d.) was used at 15°C with water as mobile phase (0.3 ml/min) and the eluate was mixed with 0.3 M McIlvaine buffer of pH 5, containing 10 mM potassium ferricyanide before detection at 390 mV. The HPLC method gave the best agreement of results on a range of juices with those of enzymatic analysis, but FIA gave better sample frequency.
Fructose Amperometry Electrode Electrode Sensor Gas diffusion

"Automated Enzymatic Assays In A Renewable Fashion Using The Multisyringe Flow Injection Scheme With Soluble Enzymes"
Anal. Chem. 2004 Volume 76, Issue 3 Pages 773-780
Nicolau Pizà, Manuel Miró, José Manuel Estela and Víctor Cerdà

Abstract: In this paper, a novel flowing stream scheme based upon the multisyringe flow injection (MSFI) technique is presented as a powerful tool to perform automated enzymatic assays. The exploitation of enzymes in homogeneous phase circumvents typical drawbacks associated with the commonly used packed-bead or open tubular permanent columns, namely, malfunctions of the reactor, carryover effects, flow resistance, loss of binding sites, large reagent consumption, and use of harmful organic solvents during immobilization procedures. The proposed MSFI system is able to handle minute volumes of soluble enzymes and accommodate reactions with divergent kinetic and pH demands, as demonstrated via the indirect chemiluminescence determination of trace levels of glucose. The procedure is based on the on-line glucose oxidase-catalyzed oxidation of β-glucose in homogeneous phase to β-glucono-δ-lactone and hydrogen peroxide. Subsequently, the generated oxidant merges downstream with an alkaline slug of 3-aminopthalhydrazide and a metal-catalyst zone (viz., Co(II)) at a total flow rate as high as 72 mL/min aiming to warrant maximum light collection from the fast CL reaction. Under optimum conditions for both sequentially occurring reactions, a glucose concentration as low as 90 µg/L may be easily detected at a 1000-fold photomultiplier gain. A second-order polynomial regression equation of light emission versus substrate concentration is found over the range 90 µg/L-2.7 mg/L glucose, although a maximum concentration of 180 mg/L may be determined by suitable gain selection without requiring manifold reconfiguration. An injection throughput of 20 h-1, a repeatability better than 2.5% at the 1 mg/L level, and a 3s detection limit of 72 µg/L are the analytical features of the designed analyzer. The proposed approach was applied to the analysis of ultralow glucose content soft drinks as well as fruit juices suitable for diabetic consumers. The accuracy was assessed using the spectrophotometric batch glucose-Trinder method as an external reference methodology for the determination of the target species in parenteral solutions.
Glucose Chemiluminescence Multisyringe