SIMULTANEOUS DETECTION OF CAROTENOIDS AND VITAMIN-E IN HUMAN PLASMA

A simplified method for analysis of the antioxidants carotenoids and v itamin E in human plasma is presented. The method is based on high-per formance liquid chromatography with a single column, a flow-rate gradi ent, and detection at 450 and 290 nm with a diode array detector. It g ives good separation of the vitamin E isomers and the major carotenoid s in plasma, with a 25 min analysis time. It was found that hydrolysis of triglycerides and cholesterol eaters is required to obtain good re covery of non-polar carotenoids such as lycopene, alpha-carotene and b eta-carotene. Two methods were used for hydrolysis of the non-polar li pids, saponification with ethanolic KOH and digestion with an enzyme m ixture of lipase and cholesterol esterase. It was found that the enzym atic digestion gave the best recoveries, better than 94% for all of th e antioxidants, and preserved several carotenoids. A plasma pool is us ed for day to day calibration of the method, which eliminates the need for stock solutions of carotenoids that are stable for only a month d ue to oxidative breakdown and their tendency to crystallize when store d at -20 degrees C in organic solvents. (C) 1997 Elsevier Science B.V.