Trace level analysis of corky off-flavor compounds: Development of a new analytical method based on solid phase extraction and analysis by multidimensional gas chromatography with mass spectrometric detection

This work describes the development of a trace level (<1 ng L−1) analysis of haloanisoles in complex wine matrix. The suggested method involves sample preparation based on solid phase extraction, a clean-up to remove acidic compounds, concentration of the haloanisole fraction and large volume on-column injection into a multidimensional GC–MS system. Mass spectrometric detection in the selected ion mode allowed reliable quantification of 2,4,6-trichloroanisole (TCA) or 2,4,6-tribromoanisole (TBA), via their highly deuterated ([2H5]) isotopologues as internal standards (stable isotope dilution analysis; SIDA), which had prior been synthesized in house. The development of this new method had become necessary, as a one-dimensional HS-SPME–GC-ECD method, routinely applied for analysis of TCA in cork soaks, had to be extended for TeCA and TBA determination, but failed due to co-elutions within wine matrices. The newly developed SPE//MDGC–MS method provided detection limits well below olfactory thresholds of the analytes with 0.05 ng L−1 (LOD), 0.19 ng L−1 (LOQ) for TCA, 0.06 ng L−1 (LOD), 0.21 ng L−1 (LOQ) for TeCA, and 0.09 ng L−1 (LOD), 0.34 ng L−1 (LOQ) for TBA.