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: Vegetable -> cabbage

Citations 5

"Multi-enzymatic Electrochemical Sensor: Field Measurements And Their Optimisation"
Anal. Chim. Acta 1999 Volume 385, Issue 1-3 Pages 461-466
N. F. Starodub, N. I. Kanjuk, A. L. Kukla and Yu. M. Shirshov

Abstract: Using such enzymes as cholinesterases, urease and glucose oxidase, and electrolyte-insulator-semiconductor (EIS)-structures with silicon nitride ion-sensitive layers as transducers investigations have been performed on the determination of heavy metal ions and phosphororganic pesticides in solutions. The content of toxic elements indicated above was determined by estimation of the residual activity of enzymatic membranes after the injection of analyzed samples, The optimal conditions were chosen for analysis of heavy metal ions and phosphororganic pesticides in potato and cabbage saps. It was shown that multienzyme analysis followed by mathematical processing is one of the effective approaches to develop computer-controlled sensor arrays for toxic substrates,
Metals, heavy Pesticides, organophosphorus Sensor Apparatus Detector Computer

"Detection And Characterization Of Phospholipase D By Flow Injection Analysis"
Anal. Biochem. 1997 Volume 244, Issue 1 Pages 55-61
M. Becker, U. Spohn and R. Ulbrich-Hofmann

Abstract: Phospholipase D was assayed by FIA (schematic diagram given) with, as substrate, liposomes prepared from phosphatidylcholine. The choline produced is converted in the presence of choline oxidase into betaine and H2O2 which was detected by Co(II)-catalyzed luminol chemiluminescence. A differential experimental set-up (diagram given) was used to study kinetic parameters of phospholipase D from Streptomycesc hromofuscus, Actinomadura spp. and Brassica oleratia. Calibration graphs were linear from 1-100 miu/ml. The detection limit was 75 pmol choline released/min which compared favourably with detection limits by amperometric (0.3 nmol), titrimetric (20 nmol) and spectrophotometric (50 nmol) detection methods. A precisely working automated system for the investigation of phospholipases D (PLDs, EC from plant and microbial sources with flow injection analysis (FIA) has been developed. The two versions of the FIA setup described are based on the oxidation of choline liberated from phosphatidylcholine by PLD action and catalyzed by choline oxidase and the chemiluminescence detection of hydrogen peroxide produced by this reaction. The correlation between this chemiluminescence signal and the PLD activity was linear in the range between 1 and 100 mU/ml PLD. The sampling frequency was 12 samples per hour. This method was used to compare three different PLDs from cabbage and microbial sources with respect to their pH optima, temperature stability, effectors, and v/[S]-characteristics.
Enzyme, phospholipase D Chemiluminescence Enzyme Automation Optimization Method comparison

"Detection Of Methamidophos In Vegetables Using A Photometric Flow Injection System"
Environ. Monit. Assess. 1997 Volume 44, Issue 1-3 Pages 375-382
J. Lui, A. Günther and U. Bilitewski

Abstract: A flow injection analysis (FIA) system using immobilized acetylcholinesterase (AChE) has been used for the detection of methamidophos in vegetable extracts. Methamidophos is one of the most commonly used organophosphate insecticides in South East Asia. AChE was immobilized onto magnetic particles; using a magnetic reactor, the particles could easily be separated from the test sample. Results show that complex matrices such as vegetable extracts have no inhibitory effect on AChE activity in the FIA system. The presence of methamidophos in the extracts caused AChE inhibition. The response could be followed as an inhibition curve and the inhibition constant calculated. Results show that using 85% AChE residual activity as the detection limit methamidophos could be detected in lettuce and cabbage at 12 and 3 mg/kg vegetable material respectively. In a simulated field situation, cabbage leaves were spiked with 20 to 40 mg/kg methamidophos, homogenized and tested in the FIA system. The corresponding methamidophos levels predicted by the experimental results came very close to the known calculated values. Data presented here suggest that it is feasible to use this system to supplement the traditional chromatographic analysis methods for methamidophos analysis.
Methamidophos Insecticide Spectrophotometry Method comparison

"Online Determination Of Trace Lead In High-salt Food By Flow Injection Hydride-generation Inductively Coupled Plasma Atomic-emission Spectrometry"
Fenxi Kexue Xuebao 1997 Volume 13, Issue 2 Pages 26-29
Yu Xin, Chen Jianguo, Wang Songqing, Liao Zhenhuan, Jiang Zucheng

Abstract: Salted vegetable (10 g) was homogenized then digested with 8 mL HNO3/HClO4 and evaporated to dryness. The residue was dissolved in 7.5 mL 0.5 M HCl and diluted with water to 25 mL. A 300 µL portion of the solution was injected into the required setup (diagram illustrated) and flowed with a carrier stream of water at 3 ml/min to react with 15% H2O2 to oxidise lower valent Pb to high valent Pb before reaction with a stream of 4% NaBH4 in 0.8% NaOH at 1.5 ml/min, transferring to the gas-liquid separator, and detection of Pb in the Ar flow by ICP-AES with measurement at 220.35 nm. The calibration graph was linear from 0.005-1 µg/ml Pb, with a detection limit of 1.6 ng/ml. When determining 50 ng/ml Pb, the RSD (n = 7) was 1.2%. By the standard-additions method, recoveries were 96.3-101.4%. The method was used in the analysis of e.g. pickled cabbage.
Lead Spectrophotometry Phase separator Standard additions calibration

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

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