Assay for both ascorbic and dehydroascorbic acid in dairy foods by high-performance liquid chromatography using precolumn derivatization with methoxy- and ethoxy-1,2-phenylenediamine.
A procedure for the simultaneous determination of both ascorbic and dehydroascorbic acid in dairy foods by high-performance liquid chromatography using precolumn derivatization with 4-methoxy- and 4-ethoxy-1,2-phenylenediamine is presented. The derivatives are isolated by solid-phase extraction and analysed by fluorescence detection on a resin-type reversed-phase column at pH 9. Retention times are 2 and 3.2 min for the derivatives of ascorbic and dehydroascorbic acid, respectively. Relative standard deviations of the within- and between-assay tests are 7.1 and 5.5%, respectively, for ascorbic and 11 and 9%, respectively, dehydroascorbic acid. The limits of detection are 50 and 70 fmol per 5-microl injection for ascorbic and dehydroascorbic acid, respectively.
Bilic
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Federal Dairy Research Institute, Liebefeld-Berne, Switzerland.
D000818:Animals; D001205:Ascorbic Acid / Q000032:analysis*; D002417:Cattle; D002611:Cheese / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003611:Dairy Products / Q000032:analysis*; D003683:Dehydroascorbic Acid / Q000032:analysis*; D007202:Indicators and Reagents; D008892:Milk / Q000737:chemistry; D010655:Phenylenediamines; D013050:Spectrometry, Fluorescence; D015014:Yogurt / Q000032:analysis
D007202:Indicators and Reagents; D010655:Phenylenediamines; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid