Determination of tocopherols and sterols in vegetable oils by solid-phase extraction and subsequent capillary gas chromatographic analysis.

In general, analyses of tocopherols and sterols are performed separately in vegetable oils. By applying solid-phase extraction (SPE) prior to capillary gas chromatography, a simple and reliable procedure for the quantification of both tocopherols and sterols in a single analytical run has been developed. SPE was used as sample clean up procedure for the separation of these minor components from the triacylglycerol matrix, replacing time consuming saponification or on-line LC-GC. The analysis of tocopherols and free sterols in five different vegetable oils illustrates robustness and reliability of this method outlined. Quantification of the analytes was performed by external calibration with reference substances and internal standardization. The recovery of the procedure as well as the repeatability of the quantitative results have been evaluated.