Separation and analysis of carotenoids and chlorophylls in Haematococcus lacustris by high-performance liquid chromatography photodiode array detection

An improved HPLC method was developed for the separation and analysis of carotenaids and chlorophylls in a green alga, Haematococcus lacustris. Six astaxanthin esters, the principal carotenoids in H. lacustris, were separated and indicated as astaxanthin esters 1-6. The retention times of the six astaxanthin esters were 11.8, 14.3, 15.0, 18.2, 22.0, and 28.4 min, respectively. astaxanthin ester 4 was the main astaxanthin ester, which accounted for 44-49% of the total astaxanthin esters. The six astaxanthin esters had the same absorption spectra, and their maximum absorption wavelengths in the mobile phase were all 481.3 nm. Relatively small amounts of p-carotene, canthaxanthin, and echinenone were detected from the alga extracts compared to astaxanthin esters, lutein, and chlorophylls. During the cultivation, the light intensity for illumination of the culture was increased from 90 to 190 mu mol/(m(2)s)) to investigate its effect on pigment formation. The content of the total astaxanthin esters was higher with enhanced light intensity after 4 days of cultivation (6.8 mg/g of dry weight) than after 8 days of cultivation (5.0 mg/g of dry weight). This HPLC method could be used to separate and determine the various algal pigments and assist in the study of biosynthesis of ketocarotenoids in algae.