DETERMINATION OF E-VITAMERS IN MICROALGAE USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH FLUORESCENCE DETECTION

No validated high-performance liquid chromatography (HPLC) methods for the determination of vitamin E in algae have been reported. We develo ped and evaluated a new procedure for the quantitation of microalgal a lpha- and gamma-tocopherol (alpha-T and gamma-T) using reversed-phase HPLC with fluorescence detection. The compounds of interest were extra cted with a mixture of petroleum ether-diisopropyl ether (3:1, v/v) af ter saponification in the presence of pyrogallol. delta-Tocopherol (de lta-T) or tocol was used as an internal standard. Linearity was achiev ed (r>0.999) over the range of 0.11 similar to 2.32 mu g/ml for alpha- T and 0.02 similar to 0.23 mu g/ml for gamma-T. The within-run coeffic ients of variation for repetitive analysis were 1.9%, 1.7% and 1.0% (n =10) for alpha-T at concentrations of 0.09, 1.24 and 1.55 mu g/ml, and 1.9%, 0.8% and 0.3% (n=10) for gamma-T at concentrations of 0.02, 0.0 8 and 0.23 mu g/ml, respectively. The recoveries at low concentration levels (0.11 and 0.02 mu g/ml) were 82.4% and 96.2% (n=5) for alpha-T and gamma-T, respectively. For medium concentrations (0.78 and 0.12 mu g/ml) and high concentrations (2.32 and 0.20 mu g/ml), the recoveries were 94.3 similar to 98.7% for the two tocopherols. The limits of qua ntitation of alpha-T and gamma-T were 20 and 5 mu g/g dry mass, respec tively. This method has been routinely used as part of nutritional stu dies on fish and shrimp larvae fed on microalgae. (C) 1997 Elsevier Sc ience B.V.