Gas chromatographic determination of major sterols in edible oils and fatsusing solid-phase extraction in sample preparation

A capillary gas chromatographic method is described for the determination o f major plant sterols and cholesterol in edible oils and fats. In the sampl e preparation procedure reversed-phase, solid-phase extraction with C18 ads orbent was used to extract the unsaponifiable matter and for sample cleanup after saponification. Sterols were quantitated as their trimethylsilylethe r derivatives using an internal standard method (betulin). The method was v alidated by recovery tests and analysis of two reference materials represen ting vegetable oil mixture and milk fat matrices. Average recoveries of spi ked cholesterol and cholesterol acetate in rapeseed oil were 103 +/- 4 % (n = 12) and 101 +/- 3 % (n = 10), respectively. The sterol values determined in the reference materials were found to be in a good agreement with their given certified or indicative values. Applied to edible oils and fats, pla nt sterols and cholesterol at levels > 20 mg kg(-1) could be accuratively q uantitated.