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
Email: schalk@unf.edu
Website: @unf

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Skimmed

Classification: Food -> milk -> skimmed

Citations 2

"Enzymatic Determinations With Rotating Bioreactors: Determination Of Glutamate In Food Products"
Anal. Chim. Acta 1998 Volume 369, Issue 1-2 Pages 147-155
Chitra Janarthanan and Horacio A. Mottola*

Abstract: The benefits of using rotating bioreactors for online or inline determination in food analyzes are illustrated with the determination of L-glutamate. Two enzymatic approaches have been implemented and samples used to illustrate the approaches included: beef and chicken bouillon cubes, soy sauce, chicken broth, seasoning salt, fruit and vegetable juices, and skim milk. One of the methods uses glutamate dehydrogenase (EC 1.4.1.3) in the main enzymatic reaction and diaphorase (EC 1.8.1.4) in the indicator reaction, which involves NADH and hexacyanoferrate(III). The monitored species, amperometrically detected at a platinum-ring electrode, is the hexacyanoferrate(II) produced by the indicator reaction. The second method utilizes a single enzyme, glutamate oxidase (EC 1.4.3.11), and amperometric monitoring of a product of the enzymatic reaction, H2O2, also at a platinum-ring electrode. Interference by ascorbate present in some samples is eliminated by inline use of a packed reactor containing ascorbate oxidase (EC 1.10.3.3). The relative merits of both systems when using continuous-flow/stopped-flow/continuous-flow processing are discussed.
Glutamate Amperometry Electrode Interferences Immobilized enzyme Stopped-flow Manifold comparison

"Determination Of Neomycin In Milk By Reversed-phase Ion-pairing Liquid Chromatography"
J. Liq. Chromatogr. Relat. Technol. 1989 Volume 12, Issue 8 Pages 1497-1515
Badar Shaikh; Jean Jackson

Abstract: Milk was skimmed and a 1 mL portion was vortex-mixed with 20% trichloroacetic acid solution (100 µL) and centrifuged at 4000 rpm and 4°C for 30 min. A 180 µL portion of the supernatant liquid was vortex-mixed with 20 µL of 1 M Na pentanesulfonate - 0.07 M acetic acid, and a 25 µL aliquot of the mixture was analyzed by HPLC on a column (15 cm x 4.6 mm) fitted with a guard column (2 cm x 4.6 mm) both containing Supelcosil LC-8-DB (5 µm) at 32.5°C. Post-column derivatization was at 33°C in a reaction coil with phthalaldehyde. The ion-pairing mobile phase contained 0.01 M pentanesulfonate, 0.056 M Na2SO4, 7 mM acetic acid and 1.5% methanol and fluorimetric detection was at 455 nm (excitation at 340 nm). A calibration graph (peak heights) was rectilinear from 0.15 to 12 µg mL-1 of neomycin in whole milk, and overall recovery was 94%, with coefficient of variation of 6.8%. The method was applied to monitor neomycin in milk after intramuscular injection at 10 mg kg-1.
Neomycin B HPLC Fluorescence Column Post-column derivatization Detection limit Calibration Peak analysis