HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH PHOTODIODE-ARRAY DETECTION OF CAROTENOIDS AND CAROTINOID ESTERS IN FRUITS AND VEGETABLES

A procedure for the simultaneous, one-step analysis of polar xanthophylls, xanthophyll mono- and diesters and geometric isomers of carotenes in selected fruits and vegetables using high-performance liquid chromatography (HPLC) and photodiode-array detector is described. The separation of carotenoid extracts was first performed on a column of 6 mu m particles using different mobile phases and variable wavelength detectors to monitor column effluents. This procedure had limitations regarding separation efficiency and ease of spectrum analysis during the chromatographic run. The method was further developed by using a column of 6 mu m particles and a mobile phase consisting of acetonitrile-isopropanol-methanol-water (39:52:5:4 v/v/v). This development permitted the isocratic separation of about 45 components in less than 50 minutes. Rapid and precise identification of the individual carotenoids was achieved by using photodiode-array detector under the control of chromatographic software which also allowed for rapid test of peak purity and complete mapping of the whole separation profile including major lipid classes and fat-soluble materials. A wide variety of carotenoids and carotenoid fatty acid esters were separated and quantified in selected fruits and vegetables such as spice red pepper, tomato, carrot, orange and apricot. cis isomers of beta-carotene, the most effective provitamin A, were also separated and differentiated from their corresponding trans forms.