An isocratic LC method for the simultaneous determination of vitamins A, C, E and beta-carotene

An isocratic liquid chromatographic method for the separation and simultaneous determination of retinyl acetate, propionate or palmitate (esters of vitamin A), beta-carotene (pro-vitamin A), ascorbic acid (vitamin C) and DL-alpha-tocopherol (vitamin E) is described. Samples are analysed by means of a reversed-phase column (LiChrospher 100 RP-18), using methanol as mobile phase. The UV Vis detector used was set at a wavelength of 300 nm and switched to 450 nm at 17 min, allowing the determination of beta-carotene. These vitamins were separated within 25 min and the detection limits ranged from 7 (beta-carotene) to 65 ng ml(-1) (ascorbic acid).