Method of simultaneous analysis of vitamins A, E and beta-carotene in dairy products

A method has been suggested for simultaneous assay of vitamins A, E and beta-carotene in milk products. A specimen sample is subjected to alkaline hydrolysis, then vitamins are extracted and separated in the column with aluminium oxide; for beta-carotene elution hexane is used, for vitamin E - acetone-hexane (10:90), for vitamin A - acetone-hexane (15:85). beta-carotene is assayed in hexane by absorption. Vitamin A and E fractions are evaporated, the residue is diluted in absolute alcohol, vitamin A is identified by absorption, vitamin E - by the colour Emmery-Engel reaction. The variation coefficient in the assay of vitamins A, E and beta-carotene was less than 10% in 5 out of 6 cases.