Development of a novel liquid/liquid extraction and ultra-performance liquid chromatography tandem mass spectrometry method for the assessment of thiols in South African Sauvignon Blanc wines

Background and Aims: The thiol compounds, 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA), are important, pleasant volatile thiols conferring fruity notes in wines. The analytical determination of these thiols in wine remains problematic due to their trace concentration and instability. The main aim of this study was to develop a liquid/liquid extraction and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the determination of 3MH and 3MHA concentration in Sauvignon Blanc wines. Methods and Results: A novel sample preparation based on a liquid/liquid extraction was developed. Thiols were quantified by UPLC-MS/MS after derivatisation with o-phthaldialdehyde. Good results were obtained with the method in terms of limit of detection and of quantification, accuracy and repeatability. Average concentration of 3MH in 18 South African wines was 1320 and of 3MHA 313ng/L. Conclusions: The analytical method described enables the liquid/liquid extraction of 3MH and 3MHA from wine, separates them by liquid chromatography and detects them by MS/MS at a concentration lower than that of their sensory threshold. Significance of the Study: The determination of the concentration of 3MH and 3MHA in Sauvignon Blanc wines could enable wine producers to predict the sensory attributes of the wine.