Rapid smoke-taint analysis of wine with SPME-GC-MS/MS

Importance of Smoke Taint Analysis

Wildfire smoke exposure can significantly impair wine aroma and flavor through volatile phenols (VPs) that impart smoky, ashy, or medicinal notes. Accurate, rapid detection of both free and glycosidically bound VPs is essential to safeguard wine quality, minimize financial losses, and guide vineyard and winemaking decisions when smoke events occur.

Study Objectives and Overview

This application note evaluates a streamlined HS-SPME-GC-MS/MS workflow using a Thermo Scientific™ TSQ™ 9000 triple quadrupole mass spectrometer coupled with a TRACE™ 1310 GC and TriPlus™ RSH autosampler. The goal is to quantify key smoke markers—guaiacol, 4-methylguaiacol, cresols, eugenol, 4-ethylguaiacol, 4-ethylphenol, and syringol—in wine, both in free form and after acidic hydrolysis of glycosides.

Methodology and Instrumentation

• Sample preparation: Model wine spiked with standards; 10 mL real wine aliquots for free VPs; 4 mL HCl hydrolysis at 95 °C for 4 h to release bound VPs.
• SPME: 50/30 µm DVB/CWR/PDMS fiber, incubation at 40 °C for 0.5 min, extraction 10 min (syringol optimized at 80 °C, 30 min).
• GC: TRACE 1310 with TG-WAXMS column, 15 min oven gradient (40→150→160→250 °C).
• MS/MS: TSQ 9000 with ExtractaBrite ion source, EI mode, selected reaction monitoring for high selectivity.

Key Results and Discussion

Calibration was linear across 0.1–100 µg/L (syringol 2.5–100 µg/L) with R² > 0.995 and ≤ 6% calibration factor RSD. Method detection limits were < 0.2 µg/L for most VPs and 1.5 µg/L for syringol. Recoveries ranged 70–130% (o-cresol 69% at low level). Carryover was < 0.1% in model and real wines. Repeatability (n = 10) showed peak area RSD < 10% (syringol 13%). Analysis of four California red wines revealed free guaiacol levels 1.7–6.0 µg/L rising to 4.8–16.8 µg/L post-hydrolysis, confirming substantial bound VP reservoirs.

Benefits and Practical Applications

• High throughput: Automated SPME and 15-min cycle support busy harvest seasons.
• Minimal sample prep: Headspace approach avoids liquid injection artifacts.
• Comprehensive quantitation: Simultaneous free and bound VP analysis informs quality decisions.

Future Trends and Opportunities

Expanding target lists to include other VP conjugates, integrating faster GC gradients, and coupling with data analytics for predictive smoke impact assessment can further enhance winery monitoring strategies.

Conclusion

The described HS-SPME-GC-MS/MS method on the TSQ 9000 platform delivers rapid, sensitive, and reliable measurement of smoke-related volatile phenols. Its robustness and automation make it well suited for quality control in commercial wine laboratories facing smoke taint challenges.

Reference

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