Sensitive high-performance liquid chromatographic analysis of plasma vitamin E and vitamin A using amperometric and ultraviolet detection.

A highly sensitive high-performance liquid chromatographic assay using amperometric detection has been developed for measuring alpha-tocopherol in plasma. Other minor components of vitamin E (beta-, gamma- and delta-tocopherols) can also be detected by this method. All-trans-retinol is simultaneously monitored by UV detection at 313 nm. This assay requires only 50 microliter of plasma for quantification of both vitamin E and A. The minimum detectable quantities for both alpha-tocopherol and retinol are 1.0 ng with corresponding signal-to-noise ratios of 4.0 and 3.5. The total chromatographic analysis time for each sample is less than 15 min. This assay has been used to determine the concentrations of vitamin A and E in plasma obtained from patients with liver disease, liver transplant patients and normal healthy volunteers.