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: Food -> margarine

Citations 5

"Automatic Determination Of Liposoluble Vitamins In Butter And Margarine Using Triton X-100 Aqueous Micellar Solution By Liquid Chromatography With Electrochemical Detection"
Anal. Chim. Acta 1995 Volume 315, Issue 1-2 Pages 201-208
M. M. Delgado-Zamarreño*, A. Sanchez-Perez, M. C. Gomez-Perez and J. Hernandez-Mendez

Abstract: An automated flow system for the determination of vitamins A, D3 and E in butter and margarine was constructed by coupling a sample treatment system (alkaline hydrolysis and SPE) with LC. A sample stream containing 2 g of butter or margarine in 25 mL of 3% Triton X-100 was merged with an alcoholic NaOH reagent stream (reagent details given) and the mixture was passed through a reactor coil (RC; 5 m x 0.05 mm i.d.). The flow from the RC was merged with 2.2 M acetic acid and passed through the Sep-Pak plus C18 SPE cartridge at 1 ml/min for 6 min. The cartridge was washed with water/methanol (3:2) for 4.5 min and then the retained analytes were eluted (1 ml/min) with methanol through a 100 µL injection loop. After 4 min the contents of the loop was injected into the LC system. The chromatography was performed on a 5 µm OD-224 RP18 column (22 cm x 4.6 mm i.d.) with a 7 µm RP18 pre-column (1.5 cm x 3.2 mm i.d.) with 2.5 mM acetic acid/sodium acetate in methanol/water (99:1) as the mobile phase (1 ml/min) and electrochemical detection at at 1.3 V vs. Ag/AgCl. Linear calibration graphs were obtained and the detection limits were 0.035, 1.8 and 0.31 µM for vitamins A, D3 and E, respectively. The day-to-day RSD (n = 10) of the method was 2.4-5.8%. Results were in agreement with those obtained by classical methods.
Vitamin A Vitamin D3 Vitamin E HPLC Electrochemical analysis Sample preparation C18 Extraction Triton X Surfactant Micelle

"Enzymic Determination Of Peroxides In Non-aqueous Media"
Analyst 1997 Volume 122, Issue 12 Pages 1543-1547
Gerardo Piñeiro Avila, Amparo Salvador and Miguel de la Guardia

Abstract: A fast enzymatic flow injection procedure was developed for the determination of peroxides in non-aqueous samples. The biochemical reaction is effected in a flow injection system using a non-covalently immobilized horseradish peroxidase reactor, followed by spectrophotometric monitoring of p-anisidine. The method provides a limit detection of 0.9 M for hydrogen peroxide, 2.6 M for tert-butyl hydroperoxide and 2.0 M for benzoyl peroxide with a maximum sampling frequency of 60 h-1. The enzyme reactor exhibits enhanced stability in water-saturated toluene, being stable for more than 4 months, and during this period an average number of 250 reactions can be performed with 1 mg of enzyme (220 purpurogallin units). The method permits the determination of peroxide in olive oil and margarine samples without any chemical pre-treatment or extraction of the sample. An average recovery of 98% was found for the determination of hydrogen peroxide in 12 different types of olive oil samples spiked with known amounts of H2O2, indicating the applicability of the procedure to real sample analysis. The procedure was also applied to the determination of H2O2 in four olive oils and a margarine sample and the results were comparable to those obtained by the reference method.
Peroxide ion Spectrophotometry Enzyme

"High Performance Liquid Chromatography And Post-column Derivatization With Diphenyl-1-pyrenylphosphine For Fluorimetric Determination Of Triacylglycerol Hydroperoxides"
J. Chromatogr. A 1992 Volume 596, Issue 2 Pages 197-202
Kazuaki Akasaka, Setsu Ijichi, Kenji Watanabe, Hiroshi Ohrui and Hiroshi Meguro*

Abstract: Butter, margarine and mayonnaise were diluted with water and extracted (x 2) with CHCl3 - methanol (2:1). The combined extracts were diluted with CHCl3 and subjected to HPLC on (a) a column (15 cm x 4.6 mm) of TSK-gel ODS 80Tm (5 µm) with a mobile phase (0.6 mL min-1) of methanol - 1-butanol (9:1) or (b) a column (15 cm x 4.6 mm) of Develosil Ph-5 phenyl column (5 µm) with a mobile phase (0.6 mL min-1) of methanol - water (19:1). In both instances, the eluent was mixed with a solution of 3 mg of diphenyl-1-pyrenylphosphine in 400 mL of methanol - acetone (3:1) pumped at 0.3 mL min-1 and the mixture was passed through a coil (20 m x 0.5 mm) at 80°C before fluorimetric detection at 380 nm (excitation at 352 nm). Calibration graphs were rectilinear for 2 to 1000 pmol of monohydroperoxides; there was no interference from dialkyl peroxides, unoxidized fatty acids, hydroxy acids or their esters. Column (a) was useful for separation of individual monohydroperoxides and column (b) was useful for their total determination as a class. The method was also be applied to the analysis of vegetable oils which were diluted with CHCl3 and subjected to HPLC as above.
Triacylglycerol hydroperoxide HPLC Fluorescence Post-column derivatization Interferences

"Highly Sensitive Flow Injection Analysis Of Lipid Hydroperoxides In Foodstuffs"
Biosci. Biotechnol. Biochem. 1996 Volume 60, Issue 11 Pages 1772-1775

Abstract: Edible oil, butter, margarine and mayonnaise samples were extracted with methanolic 50% butan-l-ol (details given). Portions (1-50 µL) of the extracts were injected into a carrier stream (0.8 ml/min) of methanolic 50% butan-l-ol, which merged a stream (0.3 ml/min) of 7.5 µg/ml diphenyl-l-pyrenylphosphine (reagent) in carrier solution containing 0.5 µg/ml 2,6-di-t-butyl-p-cresol, passed through a stainless-steel reaction coil (30 m x 0.5 mm i.d.) at 80°C then through a similar cooling coil (50 cm x 0.5 mm i.d.) prior to fluorimetric detection for lipid hydroperoxides at 380 nm (excitation at 352 nm). A second FIA system was also used which had a carrier stream flowing at 0.7 ml/min, a 30 µg/ml reagent stream flowing at 0.6 ml/min and a 50 m reaction coil. All other details were the same. For the first system the calibration graph was linear from 2-201 pmol trilinolein hydroperoxides (I), the detection limit was 2 pmol I and the RSD (n = 8) were 1.7-3.2%. For the second system, the calibration graph was linear from 0.4-79 pmol I, the detection limit was 0.2 pmol I and the RSD (n = 8) were 1.9-3.8%. Samples could be analyzed every 2 minutes, and results from both systems correlated well with those obtained by a batch method. Recoveries were 91.8-102%.
Lipids Hydroperoxide, lipid Trilinolein hydroperoxide Sample preparation Fluorescence Heated reaction Method comparison

"The Lipoxygenase Sensor, A New Approach In Essential Fatty Acid Determination In Foods"
Biosens. Bioelectron. 1997 Volume 12, Issue 11 Pages 1089-1099
Michael Schoemaker, Rainer Feldbrügge, Bernd Gründig and Friedrich Spener

Abstract: Both an enzyme electrode and enzyme column with immobilized lipoxygenase, respectively, were used for the determination of essential fatty acids. The former was applied in a batch system, the latter was part of a fully automated flow injection analysis (FIA)- system. The oxygen consumption due to the lipoxygenase catalyzed oxygenation of essential fatty acids was monitored amperometrically. Both systems were compared with regard to linear ranges of the calibration plots, sensitivities, detection limits, apparent Michaelis- Menten constants and lifetimes. The enzyme electrode showed different sensitivities for linoleic and α-linolenic acids, the most common essential fatty acids. The reason for this was not a second oxygenation step by lipoxygenase in case of α-linolenic acid, but a different dialytic behavior of the two substrates. Hence, only the FIA-system was used for the determination of these fatty acids in real matrices such as vegetable oils and margarines. In the presence of detergent the triglycerides of the hydrophobic food samples were converted into water soluble glycerol and free fatty acids by a 15 min incubation with a ready to use lipase/esterase-mix, thus avoiding the use of organic solvents for analysis. Results obtained by the enzymatic FIA-system were in excellent agreement with those obtained by standard gas chromatography.
Fatty acids, free Amperometry Sensor Immobilized enzyme Method comparison