Method for determination of gamma oryzanol in dietary supplement by high performance liquid chromatography

Gamma oryzanol (GO), a phytosterol found most abundantly in rice bran oil as well as corn, barley, rye, vegetable oils and wheat bran. Thanks to its ability to slow down the development of melanin pigments, prevent the effects and spread of ultraviolet rays on the skin's surface, limiting freckles and darkening of the skin, in recent years, GO has been added to dietary supplements to help reduce melasma, brighten and smooth the skin. For the purpose of evaluating and controlling product quality, the GO analysis method was developed and validated. GO was analyzed by HPLC using a PDA detector with a C18 chromatography column (250 mm × 4.6 mm, 5 µm) and a mobile phase consisting of methanol and acetonitrile in isocratic mode 35: 65 (v/v). The test sample was extracted with a mixture of n-hexane and ethanol at a ratio of 2: 5 (v/v). The method was evaluated for system suitability, specificity, calibration curve, precision and accuracy with limit of detection and limit of quantification were 15.0 µg/g and 50.0 µg/g, respectively. The analysis results of 10 real samples including 03 pellet samples and 07 powder samples showed that the method is suitable for analyzing samples with different concentration ranges.