Non-targeted analysis of whisky using SPME Arrow and Orbitrap Exploris GC 240 mass spectrometer

Significance of the Topic

Whisky authentication and profiling are critical in the food and beverage industry to protect product integrity, prevent economic losses from counterfeiting, and uphold regulatory compliance. The complex maturation process and variable raw materials produce distinctive chemical fingerprints that require advanced analytical techniques to differentiate genuine products from adulterated or imitation spirits.

Study Objectives and Overview

This application study aimed to demonstrate the capabilities of the Thermo Scientific™ Orbitrap™ Exploris™ GC 240 mass spectrometer combined with HS-SPME Arrow extraction for both targeted and non-targeted chemical profiling of whisky. Specific goals included quantifying key flavor compounds, distinguishing production variables (e.g., grain type, region, maturation age), and identifying markers of potential fraud using high-resolution accurate mass (HRAM) library matching and multivariate data analysis.

Methodology

Whisky samples (n=10) and blanks were prepared by diluting 100 µL of spirit to 4% ethanol in water. Target standards (3-methyl-1-butanol, 2-methyl-1-butanol, isoamyl acetate, 3-octanone) were calibrated over 0.25–40 µg·mL⁻¹. HS-SPME Arrow sampling was performed online with optimized incubation, extraction, and desorption parameters. Full-scan acquisition in EI and PCI modes (m/z 40–600) at 120 000 resolving power enabled comprehensive data collection. Quantitative and spectral deconvolution workflows were executed in Thermo Scientific™ Chromeleon™ CDS and Compound Discoverer™ software.

Used Instrumentation

• Thermo Scientific™ TriPlus™ RSH SMART autosampler with DVB/C-WR/PDMS SPME Arrow fiber
• Thermo Scientific™ Orbitrap Exploris GC 240 mass spectrometer with NeverVent™ technology
• TRACE 1610 GC system with TraceGOLD™ TG-624SilMS capillary column
• Compound Discoverer™ software with HRAM Flavor and Fragrances library and NIST 2023 library

Main Results and Discussion

• Targeted quantification showed linear calibration for key congeners with LOQs down to 0.02 µg·mL⁻¹ and R² > 0.994.
• Ratios of 3-methyl-1-butanol to 2-methyl-1-butanol highlighted sample authenticity, with outliers indicating potential adulteration.
• PCA of non-targeted profiles separated whiskies by cereal type (malted vs. unmalted), region, and age, accounting for >45% variance in PC1.
• Furfural served as a malt tracer: significantly lower in unmalted whiskies and readily visualized via trend charts.
• Volcano plots identified elevated esters (isoamyl acetate, phenylethyl acetate) and naphthalene in certain samples, suggesting flavor additive use or poor storage.
• Within Highland Scotch samples, ethyl dodecanoate and benzaldehyde differences correlated with maturation duration and possible flavor modification.

Benefits and Practical Applications

The combined HS-SPME Arrow and Orbitrap Exploris GC 240 approach delivers rapid, sensitive analysis of complex spirit matrices. High mass accuracy and resolution enable simultaneous targeted quantification and broad-spectrum fingerprinting. Integrated statistical tools facilitate routine quality control, geographical origin assignment, and fraud detection with minimal sample preparation and without venting delays.

Future Trends and Applications

Advancements may include automated machine learning models for real-time authenticity screening, expanded HRAM libraries for novel congeners, and integration with blockchain for traceability. Emerging ionization modes and miniaturized HRAM instruments could extend profiling to on-site verification in distilleries and customs checkpoints.

Conclusion

This study demonstrates the effectiveness of HRAM GC–MS combined with SPME Arrow for comprehensive whisky characterization. The workflow enables precise quantification of flavor markers, robust non-targeted fingerprinting, and reliable detection of adulteration indicators, supporting quality assurance and anti-counterfeiting efforts in the spirits industry.

Reference

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