Qualitative Screening of Volatile Thiols in Wine by Selective Silver Ion Solid-Phase Extraction with Heart-Cutting...

The chemical analysis of odorous volatile thiols is intrinsically challenging. Substantial progress has been made in quantitative analysis of targeted thiols at ultra-trace concentrations (ng/L), but lesser analytical attention has been given to the qualitative screening of unknown thiols. This work presents a solid-phase extraction (SPE) method using a silver ion (Ag⁺)-based sorbent to isolate volatile thiols from red wine. This proposed Ag⁺ SPE method was effective (recovery: 87-101% for four non-furan thiols and 35-49% for two furan thiols), simple, safe, and greatly reduced artifacts, testifying to its suitability as the sample preparation protocol for a qualitative screening experiment. Separation and detection were conducted using heart-cutting multidimensional gas chromatography coupled to mass spectrometry/olfactometry (H/C MDGC-MS/O). Key parameters including H/C width, main host oven temperature, and cryogenic trapping temperature were investigated for optimal instrument performance. The developed Ag⁺ SPE H/C MDGC-MS/O strategy was readily applicable for qualitative screening of odorous volatile thiols in wine, as demonstrated by two case studies.