Comparison of two SPME fibers for the extraction of some off-flavour cork-taint compounds in bottled wines investigated by GC-HRMS

Headspace solid-phase microextraction (HSSPME) coupled to gas chromatography with high-resolution mass spectrometry (GC–HRMS) was used to determine 2,4,6- trichloroanisole, 2,3,6-trichloroanisole, 2,3,4-trichloroanisole, 2,3,5,6-tetrachloroanisole, pentachloroanisole, 2,4,6-tribromoanisole, 2-methylisoborneol, and 4-ethylguaiacol in wine samples. Two types of fiber coating commonly employed for sampling trichloroanisoles in wine and cork stoppers, viz. a polar mixed 50/30 μm divinylbenzene/carboxen/ polydimethylsiloxane (DVB/CAR/PDMS) and a nonpolar 100 μm polydimethylsiloxane (PDMS), both 1 cm in length, were compared. This study demonstrates that the most employed polar mixed fiber should not be used with ethanol– water solutions, viz. wine samples, as its coating is not chemically and mechanically robust for sample extractions, as confirmed by environmental scanning electron microscopy. Much more effective and reliable results were obtained with the PDMS fiber, which remained functional for more than 80 analyses of red and white wine samples with satisfactory extraction efficiencies. Detection limits of investigated compounds, under optimized experimental conditions, ranged from 0.2 to 0.4 ng/L at a signal-to-noise ratio of 3 and quantification limits from 0.8 to 1.5 ng/L. The proposed method was successfully applied to commercially available Italian white and red wines using 2,4,6-TCA-d5 as the internal standard.