Simultaneous determination of vitamins C, E and beta-carotene in human plasma by high-performance liquid chromatography with photodiode-array detection.

To develop a high-performance liquid chromatography (HPLC) method with photodiode-array ultraviolet detection for the simultaneous determination of vitamin C, vitamin E and beta-carotene. Following liquid-phase extraction from the human plasma samples, these three vitamins were successfully separated on the LiChrospher 100 RP-18 column (125 x 4 mm I.D.; particle size, 5 microm) at a flow-rate of 1.2 ml/min, with a mobile phase of methanol-acetonitrile-tetrahydrofuran (75: 20: 5, v/v/v). The limits of quantitation were 100, 0.25 and 0.25 microg/ml for vitamin C, vitamin E and beta-carotene respectively. The method is linear over the studied range of 0.25 to 5 g/ml for vitamin E and beta-carotene and 100 to 5000 microg/ml for vitamin C. The extraction recoveries were greater than 83% for these three vitamins. The within day and between-day precision of the analysis did not exceed 15.3 and 16.2%, respectively. A suitable method to determine the concentration of vitamin C, vitamin E and beta-carotene following oral administration of antioxidant supplement capsules to a healthy Chinese volunteer.