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: Meat -> pork

Citations 3

"Amperometric Flow Injection Method For Determination Of Biogenic Diamines And Hypoxanthine By Combined Use Of Immobilized Enzyme Reactors And A Peroxidase Electrode"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 161-165
Toshio Yao*, Masahiro Satomura and Tamotsu Wasa

Abstract: The sample solution (50 µL) was injected into a carrier solution (0.1 M pyrophosphate buffer of pH 8.7), then the flow was split between two reactors containing putrescine oxidase and xanthine oxidase, respectively, immobilized on controlled-pore glass. A delay coil was incorporated in the latter flow line so that two peaks would be obtained for each sample. The flows were reunited before introduction of a mediator solution [1.0 mM Fe(CN)64- in 0.1 M phosphate buffer of pH 7.0] and flow-through a mixing coil to a cell equipped with a vitreous carbon electrode on which peroxidase had been cross-linked by glutaraldehyde for amperometric measurement of the H2O2 formed in the two enzymatic reactions. The first and second signals corresponded to total polyamines (cadaverine, spermine and putrescine) and to hypoxanthine, respectively. The calibration graphs were rectilinear from 1 to 500 µM and the detection limit was 0.5 µM for polyamines or for hypoxanthine. Both reactors maintained adequate activity during repetitive use for 40 days. The method was applied to a deproteinized aqueous extract of pork loin meat undergoing storage at 5°C. A flow injection system is proposed for the determination of meat freshness, based on the simultaneous determination of polyamines and hypoxanthine. A putrescine oxidase reactor and xanthine oxidase reactor were incorporated at fixed positions in a flow system, which was based on the splitting of the flow after sample injection and subsequent confluence before reaching the peroxidase electrode. Because each channel has a different residence time, two peaks were obtained. The first peak corresponded to the total polyamine concentration. (putrescine, cadaverine and spermidine); the second peak to hypoxanthine. The calibration graphs were linear in the range 1 x 10^-6-5 x 10^-4M. The detection limit was 0.5 x 10^-6 M for polyamines and hypoxanthine. The measurement of polyamines and hypoxanthine contents in porcine loin meat could be performed at a rate of 25 samples per h with satisfactory precision (<1.5% RSD).
Amines, biogenic Hypoxanthine Cadaverine Spermine Putrescine Amperometry Electrode Immobilized enzyme Controlled pore glass Sample splitting Dual detection

"D-Lactic Acid In Pork As A Freshness Indicator Monitored By Immobilized D-lactate Dehydrogenase Using Sequential Injection Analysis"
Anal. Chim. Acta 1993 Volume 283, Issue 2 Pages 727-737
Hun-Chi Shu, H&aring;kan H&aring;kanson and Bo Mattiasson

Abstract: Ground pork, homogenized with 1 M HClO4 for 10 min was diluted with water, the pH was adjusted with 2 M KOH to 10^-11 and the solution was further diluted with water. D-Lactic acid (I) was determined in the solution by a fully computerized sequential injection analysis system. A dual-piston, sinusoidal flow pump was used to aspirate the following liquid segments into the holding tube: (i) 0.1 M glycylglycine buffer containing 0.07 M glutamate of pH 10 (buffer A); (ii) 4 mM NAD+ solution; (iii) sample solution; (iv) 4 mM NAD+ solution; and (v) buffer A. The direction of the piston was reversed and v, iv and iii were transported to the enzyme column (3 cm x 4 mm i.d.) containing D-lactate dehydrogenase and L-alanine aminotransferase immobilized onto silica beads. The flow was stopped for 90 s. The piston was moved forward to expel all the reagent and products through the detector cell (30 µL) where the absorbance of NADH was measured at 340 nm. The calibration graph was linear up to 10 mM I and the detection limit was 0.1 mM. The RSD (n = 5) was 3%. The method was used to measure the change in I concentration in pork during vacuum- and chilled-storage.
d-Lactic acid Spectrophotometry Sample preparation Sequential injection Immobilized enzyme Silica Stopped-flow

"Liquid Chromatographic Analysis Of Thiamine And Its Phosphates In Food Products Using Amprolium As An Internal Standard"
J. Micronutr. Anal. 1986 Volume 2, Issue 3 Pages 189-199
Huang, M. H.A.

Abstract: Samples of food (e.g., pork, chicken, ham, bread, cereal, almonds or peanut butter) were blended (if necessary) and mixed with 5% sulfosalicylic acid solution and amprolium (internal standard). The mixture was extracted with hexane, and the extract was cleaned-up on a column (30 cm x 6 mm) of Bio-Rad AG 2-X8 anion-exchange resin with elution by using 0.1 M sodium phosphate buffer (pH 5.5). The eluate was analyzed by HPLC on a column (3 cm x 3 mm) of C18 material (3 µm) with a mobile phase (1 mL min-1) of two 0.1 M sodium phosphate buffers (pH 5.5 and 2.6) for 6 min and 19 min, respectively. Fluorimetric detection was at 432 nm (excitation at 339 nm) after post-column derivatization of thiamine and its phosphates to their thiochrome derivatives.
Thiamine Thiamine monophosphate HPLC Fluorescence Post-column derivatization