Development of a simple and economical analytical method for the quantification of astaxanthin E/Z-isomers

Abstract

[Purpose] Astaxanthin contains multiple conjugated bonds in its molecular structure, which theoretically allows a large number of E/Z-isomers. Thus, the accurate analysis and quantification of astaxanthin E/Z-isomers is required; however, this is a challenging task. The aims of this study were to develop a simple and cost-effective analytical method employing reversed-phase HPLC for separating astaxanthin E/Z-isomers and assessing their distribution in foods, processed products, and cosmetics.

[Methods] We assessed different stationary phases, including C18-, C30-, and cholesteryl group-bonded silica columns, along with different compositions of mobile phase and column oven temperatures.

[Results and Discussions] The developed reversed-phase HPLC method with a C18 column efficiently separated all of the major isomers of astaxanthin within 20 min. Astaxanthin isomer separation by cholesteryl group-bonded silica columns was inferior to that of C18 and C30 columns. The developed C18-HPLC method was able to efficiently assess astaxanthin E/Z-isomers in commercially available foods, processed foods, and cosmetics.