Silver ion spray reagent for the discrimination of β- and ε-end groups in carotenoids on thin-layer chromatograms

Abstract

Thin-layer chromatograms of pure carotenoids and natural carotenoid mixtures were dried and sprayed with saturated methanolic silver nitrate solution. Those carotenoids containing β-end groups showed a marked bathchromic colour change for each such end group. Thus, β-carotene, β-cryptoxanthin and zeaxanthin gave a clear red colour while α-carotene, α-cryptoxanthin and lutein gave deep organge spots after such treatment. Taraxanthin and antheraxanthin could be similarly distinguished. The method was not applicable to paper chromatography.