Analysis of carotenoids in vegetables by HPLC
1992
Tee Siong, E. | Lim Chin Lam (Institute for Medical Research, Kuala Lumpur (Malaysia). Div. of Human Nutrition)
Eight vegetables were pre-treated with and without saponification, and chromatographed by reversed-phase HPLC. Carotenoid peaks were identified using seven reference standards. Sample extracts were also chromatographed using a mixed magnesia and diatomaceous earth column. Fractions were eluted using stepwise increases in the proportion of acetone in hexane, studied by UV-VIS absorption spectrophotometry, and re-chromatographed by HPLC. The major carotenoids, alpha- and beta-carotenes, although there appeared to be some loss of lutein and lycopene were thus identified. Saponification removed various non-carotenoid pigments in green vegetables, resulting in HPLC profiles which were easier to quantitate, while prolonging the life of the HPLC column. The process did not result in a drastic loss of alpha- and beta-carotene, although there appeared to be some loss of lutein, which possesses no pro-vitamin A activity. "Total carotenoid content" of the saponified vegetables could be obtained from the absorbance reading of the extracts at 450 nm.
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