Simple Quantitative Determination of Potent Thiols at Ultratrace Levels in Wine by Derivatization and High-Performance Liquid Chromatography–Tandem Mass Spectrometry (HPLC-MS/MS) Analysis

Abstract

Volatile sulfur compounds contribute characteristic aromas to foods and beverages and are widely studied, because of their impact on sensory properties. Certain thiols are particularly important to the aromas of roasted coffee, cooked meat, passion fruit, grapefruit, and guava. These same thiols enhance the aroma profiles of different wine styles, imparting pleasant aromas reminiscent of citrus and tropical fruits (due to 3-mercaptohexan-1-ol, 3-mercaptohexyl acetate, 4-mercapto-4-methylpentan-2-one), roasted coffee (2-furfurylthiol), and struck flint (benzyl mercaptan), at nanogram-per-liter levels. In contrast to the usual gas chromatography (GC) approaches, a simple and unique high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for routine analysis of five wine thiols, using 4,4'-dithiodipyridine (DTDP) as a derivatizing agent and polydeuterated internal standards for maximum accuracy and precision. DTDP reacted rapidly with thiols at wine pH and provided stable derivatives, which were enriched by solid-phase extraction (SPE) prior to analysis by HPLC-MS/MS. All steps were optimized and the method was validated in different wine matrices, with method performance being comparable to a well-optimized but more cumbersome gas chromatography-mass spectrometry (GC-MS) method. A range of commercial wines was analyzed with the new method, revealing the distribution of the five thiols in white, red, rosé, and sparkling wine styles.

Spotlight on Varietal Thiols and Precursors in Grapes and Wines

“…potential for oxidation and binding to surfaces). [13,29] Several GC-MS methods were available but they were not overly attractive owing to requiring the use of mercury complexes or elaborate procedures for thiol isolation, or less common instrumentation having chemical ionisation functionality. [7] Aiming to avoid some of these drawbacks, in 2011, we developed a method for 3SH to be able to relate our precursor results to winemaking outcomes.…”

“…However, rather than determine thiol concentrations spectrophotometrically (trace levels of varietal thiols would be swamped by other thiols present), we used it in conjunction with HPLC-MS/MS analysis. [29] We optimised the full procedure, which involved spiking wine with labelled internal standards (another SIDA method), adding EDTA, 50 % acetaldehyde solution, and DTDP reagent, isolating derivatives by SPE, and analysing them by HPLC-MS/ MS with MRM. Acetaldehyde was added to bind bisulfite, which we found would otherwise consume all of the derivatising reagent and lead to poor detection of varietal thiols.…”

Unravelling glutathione conjugate catabolism in Saccharomyces cerevisiae: the role of glutathione/dipeptide transporters and vacuolar function in the release of volatile sulfur compounds 3-mercaptohexan-1-ol and 4-mercapto-4-methylpentan-2-one

“…2 were carried out using a recently published method (Capone et al 2015). This method involved taking an aliquot (20 ml) of sample, spiked with deuterium-labelled standards (d 10 -4-MMP, d 10 -3-MH and d 5 -3-MHA; 500 ng/L final concentration of each), following the addition of EDTA 2Na (20 mg), 50 % acetaldehyde (80 μL) and the derivitising reagent (10 mM, 200 μL).…”

“…Data with the same letter are not significantly different from each other (Tukey's test, P < 0.05). Data was analysed using the method described in Capone et al (2015) but significant decrease in 4-MMP concentration (5 % less than the wild-type, P < 0.001), while the deletion of DUG3 had no effect (P = 0.785). Interestingly, the concentration of GSH-4-MMP-derived 4-MMP increased by approximately 50 % in the vam1Δ strain.…”

Study on detection methods for sorbitol

“…In recent years, HPLC has been combined with many sensitive detection techniques and has experienced continuous improvement of stationary phases, which have improved its sensitivity and specificity. HPLC is currently widely used for the analysis of drugs and dosage forms with respect to quality control, quantitative determination of active ingredients and impurities, monitoring drug blood concentration in patients, and bioequivalence assessment [10][11][12].…”