Solid-phase microextraction - On-fibre derivatization with comprehensive two dimensional gas chromatography analysis of trans-resveratrol in wine

Trans-resveratrol, found in wine, grapes, peanuts, soy and tea, is one constituent of the polyphenol class which is reported to be beneficial to animal health. The analysis of trans-resveratrol may be accomplished by use of solid-phase microextraction (SPME), with on-fibre derivatization in order to improve the subsequent GC analysis (to increase the volatility and recovery) of the extracted solute. An 85 μm polyacrylate SPME fibre was selected for this study, and the SPME method incorporated a modification to the procedure to remove moisture and permit the use of water sensitive derivatizing reagents. Both BSTFA and ocetic anhydride reagents were tested. Comprehensive two-dimensionol gas chromatography (GC x GC) with a cryogenic modulation system was employed for the final chromatographic separation step. It was found that successful separation of resveratrol derivatives from potential interferences, that cause peak overlap in single column GC analysis of complex red wine somples, could be ochieved. This increased separation power allows more accurate quantitative results for extracted trans-resveratrol. Reproducible positioning of the trans-resveratrol peak in the 2D separation space was found in the SPME-GC x GC experiment, consistent with other studies on GC x GC retention reproducibility. Colibration curves for peak area were prepared for SPME extracted resveratrol, for both derivatising reagents, and good linearity (R² ca. 0.998) was achieved. The trans-resveratrol content of five Australian red wine samples was determined by using the acetic anhydride derivatizing reagents, and optimum conditions for the analysis were established.