A Multiresidue Derivatization Gas Chromatographic Assay for Fifteen Phenolic Constituents with Mass Selective Detection

We have developed a GC/MS method to simultaneously measure the concentrations of 15 biologically active phenolic components of wine:  vanillic acid, gentisic acid, m- and p-coumaric acid, gallic acid, ferulic acid, caffeic acid, cis- and trans-resveratrol, epicatechin, catechin, morin, quercetin, and cis- and trans-polydatin. Wine (1 mL) was diluted 1:1 with water to reduce the alcohol content and extracted on a preconditioned C-8 solid-phase extraction cartridge. The phenolic compounds were eluted with ethyl acetate, evaporated to dryness, and derivatized with bis(trimethylsilyl)trifluoroacetamide/pyridine. The TMS derivative of each phenolic compound was analyzed on a GC/MSD coupled to a DB-5HT capillary column using one target and two qualifying ions for each compound in a total run time of 26 min. Resolution and quantitation of all compounds were excellent, with linear calibration curves over a wide range. The lowest detection limit was for gentisic acid (24 μg/L) and highest for quercetin (843 μg/L). The average percent recovery and coefficient of variation (mean precision) ranged from 90.7 to 104.6 (except morin, 72.2%) and 4.0 to 10.2 (except morin, 16.1%, and quercetin, 16.0%) respectively. This method has been applied to solid vitaceous plant materials as well as wine and should be suitable to measure polyphenols in fruit, vegetables, and other foods provided that efficient extraction techniques are employed.