determination of total l-ascorbic acid by high performance liquid chromatography in human plasma

the total vitamin c content in human plasma is widely accepted as an indicator of the tissue status of vitamin c. a liquid chromatography method with ultraviolet detector (264 nm) for measuring ascorbic acid in human plasma was developed. a c18 reversed-phase column and cetrimide as an ion-pairing agent was employed. ascorbic acid (aa) was measured after reducing l-dehydroascorbic acid to l-ascorbic acid with dithiothreitol. the stability of the ascorbic acid in plasma, metaphosphoric acid and trichloroacetic acid was also evaluated. the analytical parameters, including linearity (1-60 µg/ml), accuracy (98.98%), repeatability (2.8%) and reproducibility (7.2%), showed that the method is reliable for measuring the total vitamin c content in plasma.