Stability of carotenoids [of fishes] on silica gel and other adsorbents [beta carotene, cauthaxanthin, lutein, zeaxanthin, isozeaxanthin, astaxanthin ester]

β-Carotene, canthaxanthin, lutein, zaxanthin, isozeaxanthin and astaxanthin ester were separated on column chromatogaraphy, using magnesium oxide, alumina, Micro-Cel C and silica gel as adsorbents. Magnesium oxide was found to be the most inert adsorbent; the next was alumina. β-Carotene, canthaxanthin, lutein, zeaxanthin, and astaxanthin ester, separated and purified on a silica gel column, were decomposed or converted to other compounds depending on the duration of time on the column. It was proposed that when zeaxanthin was chromatographed on a silica gel column, zeaxanthin was converted to another compound which has high absorbance on the ultravioled side through mutatoxanthin and auroxanthin. When purified on a EDTA pre-treated silica gel adsorbent, using cyclohexane as the developing solvent, zeaxanthin was stable on that column for 8 h.