Determination of L-Ascorbic Acid£¬D-Isoascorbic Acid£¬Dehydroascorbic Acid and Total Vitamin C in Fruit and Vegetable by HPLC

KeyWord:HPLC  L-ascorbic acid  D-isoascorbic acid  dehydroascorbic acid  fruit  vegetable

Abstract:

      A reliable and simple method was developed for the determination of L-ascorbic acid£¬D-isoascorbic acid£¬dehydroascorbic acid and total vitamin C in fruit and vegetable by high performance liquid chromatography(HPLC).The fruit or vegetable sample were extracted with metaphosphoric acid.L-Ascorbic acid and D-isoascorbic acid in extract were directly determined by HPLC with ultraviolet spectrophotometric detection.Dehydroascorbic acid in extract was reduced to L-ascorbic acid by L-cysteine in trisodium phosphate(pH 7. 0-7.2) solution£¬and then total vitamin C was determined.The dehydroascorbic acid was calculated by substracting L-Vc from total vitamin C.The analytes were separated on a C18 column using methanol-0.01 mol/L phosphate buffer (pH 3.5) as mobile phase£¬and analyzed quantitatively at UV wavelength of 245 nm by the external standard method.The calibration curves for L-ascorbic acid and D-isoascorbic acid were linear in the range of 0.5-50 mg/L with correlation coefficients more than 0.999.The limits of detection were 42.0 ¦Ìg/kg for L-ascorbic acid£¬19.4 ¦Ìg/kg for D-isoascorbic acid and 262 ¦Ìg/kg for dehydroascorbic acid.The average recoveries of three substances in four matrices ranged from 82.8% to 111.3% with relative standard deviations(RSD) less than 15% at three spiked levels.The method was simple£¬sensitive and accurate£¬and was suitable for the determination of L-ascorbic acid£¬D-isoascorbic acid£¬dehydroascorbic acid and total vitamin C in fruit and vegetable samples.