A chromatographic procedure for the determination of carotenoids and chlorophylls in vegetable products

Pigments, such as carotenes, xanthophylls and chlorophylls, were extracted from both vegetables and their industrial products by using a 2:1 (v/v) dichloromethane/methanol solution. To separate and quantify the components in the extraction mixture, a HPLC analysis on reversed phase C-30 column and binary gradient, made of methanol/water solution and dichloromethane, was employed. This gradient appears to have some advantages over other reported methods, which utilize reversed phase C-30 column, in terms of resolution and analysis time. The linearity range of the detection response, the chromatographic resolution of a standard mixture constituted of lutein, zeaxanthin, trans-beta-apo-8'-carotenal, beta-cryptoxanthin, chlorophyll-b, alpha-carotene, chlorophyll-a, beta-carotene, lycopene and the conditions for the complete extraction of those substances from the vegetable matrix were investigated. Both retention time and peak area reproducibility showed an average variation coefficient of about 2% for all the analyzed compounds. As a consequence of the good chromatographic separation of chlorophylls from carotenoids, sample saponification was found unnecessary when analyzing green vegetable products. Finally, to illustrate the applicability of the method, the presence of carotenoid esters in tomato and orange products was examined.