Simple and Direct Analysis of Phytosterols in Red Palm Oil by Reverse Phase HPLC and Charged Aerosol Detection

Phytosterols (PSs) are a group of naturally occurring steroid alcohols found in plants. There is considerable interest in PSs as dietary supplements as they are reported to lower cholesterol levels and also have a positive impact on cardiovascular diseases. However, recent research suggests that PS supplementation may aggravate atherosclerosis and lead to aortic valve stenosis. PSs are typically measured by gas chromatography (GC), but this approach is time-consuming since it requires saponification of the sample, several extractions, and derivatization. We developed a simplified method using reversed-phase, HPLC and charged aerosol detection (CAD). CAD is sensitive, has a dynamic range of >4 orders of magnitude, can measure any non-volatile species, and analytes shows similar response independent of their chemical structure. Samples were prepared by simple dilution prior to analysis. Five PSs, campesterol, cholesterol, stigmasterol, beta-sitosterol, and stigmastanol, were resolved in <35min. Calibration curves showed linear correlation coefficients >0.997. The LOD was <=5ng (on column). Analysis of red palm oil is used as an example. The method is simple to use, has good linearity and sensitivity, and is capable of measuring numerous PSs in plant extracts. This approach can be used to examine product purity, supplement content, and adulteration.