An HPLC method using photodiode array detector (PDA) detector has been developed for the determination of astaxanthin, lutein, and zeaxanthin in dietary supplements. These compounds were separated on a C30 chromatography column with ethyl acetate: acetonitrile (12:88, v/v) containing 0.1% n-decanol as the mobile phase. Xanthophyll compounds, usually existing in the form of esters, were saponified in 45% KOH solution (with lutein and zeaxanthin) and 1% (with astaxanthin) at 60°C within 15 minutes, then re-extracted with n-hexane before analyzing on HPLC system. The method was validated and had good specificity and selectivity. The linear calibration curve in the range of 0.5 - 10 µg/ml, the repeatability and the recovery of the method meet the analytical requirements according to AOAC; the method was applied to analyze several dietary supplements collected from market.
xanthophyll, lutein, zeaxanthin, astaxanthin, dietary supplement, HPLC
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