Using HS-SPME and GC/Triple Quadrupole MS for High Throughput Analysis of Haloanisoles in Wines at Sub-ng/L Levels

Importance of the Topic

Headspace solid-phase microextraction (HS-SPME) coupled with tandem mass spectrometric detection enables sensitive and rapid monitoring of haloanisoles in wine at concentrations below sensory thresholds. Haloanisoles such as 2,4,6-trichloroanisole (TCA), tetrachloroanisole (TeCA), pentachloroanisole (PCA), and tribromoanisole (TBA) cause cork taint, a musty off-aroma that can affect 1–5% of market wines, leading to significant economic losses for producers and allied industries. Effective quality control requires analytical methods combining low detection limits, high selectivity, and throughput compatible with production environments.

Objectives and Overview

This study aims to develop and validate an automated HS-SPME/GC-triple quadrupole MS/MS method for quantifying TCA, TeCA, PCA, and TBA in wine. Key objectives include:

• Achieving limits of quantification (LOQs) below sensory threshold levels (≤1 ng/L).
• Minimizing sample preparation and analysis time for high throughput.
• Incorporating stable isotope-labeled internal standards for accurate quantitation.
• Evaluating method performance in model and commercial wine matrices, including consumer-reported tainted samples.

Methodology and Instrumentation

Sample Preparation and Extraction:

• Aliquot 10 mL wine into 20 mL amber vials; add internal standards ([2H5]-TCA, [13C6]-PCA at 5 ng/L; [2H5]-TBA at 10 ng/L).
• Pre-agitate samples at 40 °C, 500 rpm for 5 minutes.
• Extract headspace volatiles using a 100 µm PDMS SPME fiber for 10 minutes at 250 rpm agitation.
• Thermally desorb analytes in the GC inlet at 280 °C for the entire oven program (11 minutes) to avoid carryover.

Instrumental Configuration:

• Gas chromatograph: Agilent 7890A with SPME inlet liner, splitless injection (1.2 min split flow change).
• Autosampler: Gerstel MPS2 for automated headspace SPME handling.
• Mass spectrometer: Agilent 7000B triple quadrupole MS operating in EI mode with multiple reaction monitoring (MRM), collision gas N2 (1.5 mL/min), helium quench (2.25 mL/min).
• Chromatographic column: DB-5, 30 m × 0.25 mm, 0.25 µm film; oven ramp from 40 °C to 280 °C at 30 °C/min with 3 min hold.

Key Results and Discussion

Linearity, LOD and LOQ:

• Calibration in model wine (0.1–50 ng/L for TCA, TeCA, PCA; 0.5–50 ng/L for TBA) yielded correlation coefficients > 0.999.
• LOQs achieved: 0.5 ng/L (TCA), 0.1 ng/L (TeCA), 0.25 ng/L (PCA), 1.0 ng/L (TBA), all below sensory thresholds (3–15 ng/L for chlorinated analytes, 10 µg/L for brominated).

Recovery and Precision:

• Spike recoveries in diverse red and white wines ranged from 90 to 110%, with RSDs < 10% for most conditions.
• No significant matrix interferences detected, owing to targeted MS/MS selectivity and stable isotope correction.

Analysis of Consumer-Reported Tainted Wines:

• In three tainted wines, TCA was most abundant (2.3–9.9 ng/L), often exceeding its threshold. Other haloanisoles were 5–10× lower or undetected.

Benefits and Practical Applications

• High sensitivity and specificity facilitate early detection of haloanisole contamination, supporting quality assurance in wineries and cork suppliers.
• Automated HS-SPME handling and 15-minute total extraction time enable >4 samples per hour throughput.
• Stable isotope internal standards correct for variability, ensuring reliable quantitation across complex matrices.

Future Trends and Applications

• Expansion to additional off-flavor compounds and broader food matrices through multiplexed MRM methods.
• Integration of faster SPME coatings or alternative sorptive materials for sub-10 minute extraction.
• Coupling with high-resolution or real-time detection techniques for comprehensive volatile profiling.
• Development of portable GC/MS platforms for in-situ monitoring during production and bottling.

Conclusion

The described HS-SPME/GC-MS/MS method offers a robust, rapid, and highly sensitive approach for quantifying trace haloanisoles in wine. Achieving LOQs below sensory thresholds and demonstrating excellent recovery and precision, the technique supports routine high-throughput monitoring to prevent cork taint and ensure product quality.

References

• A.K. Hjelmeland et al. Am. J. Enol. Viticult. 63, 494-499 (2012).
• T.J. Evans et al. J. Chromatogr. A 786, 293-298 (1997).
• C. Fischer and U. Fischer. J. Agric. Food Chem. 45, 1995-1997 (1997).
• T.S. Collins et al. In Recent Advances in Analysis of Food and Flavors, ACS (2012).