determination of vitamin c in small volumes of blood by hplc/ec

a sensitive procedure for determining total vitamin c (ascorbic acid + dehydrate ascorbic acid) in a blood drop from a finger prick, before and after the adminis- tration of a vitamin c tablet is described. analysis was carried out by high per- formance liquid  chromatography with  electrochemical detection (hplc/ec). measurements were taken one hour, two hours and six hours after the administra- tion of a 500 mg vitamin c tablet. d-isoascorbic acid was used as the internal standard and analysis was carried out using two c-18 columns connected in series and a phosphate buffer mobile phase. dehydroascorbic acid in the samples was converted to ascorbic acid by incubation with dl-homocysteine for 30 minutes. the level of vitamin c in blood reached a maximum concentration after two hours.