HEADSPACE SOLID-PHASE MICROEXTRACTION ANALYSIS OF VOLATILE SULFIDES AND DISULFIDES IN WINE AROMA

Sulphur compounds (S-compounds) are important constituents of wine off -flavours. Headspace solid-phase microextraction (HS-SPME) combined wi th gas chromatography coupled to flame photometric detection (GC-FPD) was used to develop a suitable method to analyse volatile sulphides an d disulphides. This is a very simple and fast technique which gives go od reproducibility at mu g/l levels (relative standard deviations<10%) . The analytes were extracted from the headspace of the samples by usi ng either polydimethylsiloxane or polyacrylate coated fused-silica fib ers in an SPME unit. Then, the fiber was inserted into the injector of a gas chromatograph and the extracted S-compounds were thermally deso rbed. The influence of different parameters, such as ionic strength, s tirring, headspace volume, ethanol concentration, time and temperature of extraction, was studied. The extraction of the fibers varies consi derably for the different sulphur compounds studied. The most volatile compounds were the least extracted by the coating fibers tested. The standard additions technique, applied to real samples, gave the recove ries >94%. The detection limits range between 3 mu g/l and 50 ng/l. Th e overall process was successfully applied to identify and quantify S- compounds in white and red wines. (C) 1998 Elsevier Science B.V. All r ights reserved.