Optimization of headspace sampling using solid-phase microextraction for chloroanisoles in cork stoppers and gas chromatography ion-trap tandem mass spectrometry analysis

In a study aiming to characterize cork off-flavour for quality control purposes, chloroanisoles were extracted and identified from cork stoppers by means of solid-phase microextraction (SPME)-gas chromatography-ion-trap mass spectrometry (GC-ITMS). An experimental design procedure was used to investigate the effects of some experimental parameters on the SPME of 2,4-dichloroanisole, 2,6-dichloroanisole, and 2,4,6-trichloroanisole from cork stoppers by using a Carboxen-PDMS 75 lam fibre. Variables such as extraction temperature, extraction time, and percentage of ethanol added to the matrix were optimized to improve extraction efficiency of chloroanisoles onto SPME fibre. Instrumental analysis was performed by GC-ITMS in the MS/MS mode. Preliminary analyses on standard solutions allowed selection of the appropriate ionization mode (i. e. electron impact or chemical ionization), providing for each analyte the highest instrumental response. In order to find polynomial functions describing the relationships between variables and responses, the analytical responses, i.e. the chromatographic peak areas, were processed by using the backward multiple regression analysis. For all the analytes the operating conditions providing the highest extraction yield inside the experimental domain considered were found.