IVAS 2017: Chemical Profiling and Differential Analysis of Whiskies using Exactive™ GC Orbitrap™ GC-MS

Significance of the Topic

Whisky authenticity and quality control have become critical in a global market threatened by adulteration and counterfeiting, with annual losses in the billions. Detailed chemical profiling allows producers and regulators to monitor product consistency, understand the impact of maturation and storage, and protect brand integrity.

Objectives and Study Overview

This study aimed to demonstrate a proof‐of‐concept workflow using high‐resolution Orbitrap GC‐MS to differentiate and profile a variety of whisky samples. Variations in spirit type (bourbon versus single malt Scotch), geographical origin (USA versus Scotland, and different Scotch regions), and aging duration (10, 12, 15, 18 years or no age statement) were investigated.

Methodology and Instrumentation

Whisky extracts were prepared in ethyl acetate and analyzed in quadruplicate alongside a pooled quality‐control sample. Separation was performed on a Thermo Scientific Trace™ 1310 GC coupled to a Q Exactive™ GC Hybrid Quadrupole‐Orbitrap MS operating at 60,000 resolution (FWHM @ m/z 200) in full‐scan EI mode. Data processing involved Compound Discoverer™ for peak alignment, statistical evaluation (PCA, volcano plots) and Thermo Scientific TraceFinder™ for deconvolution and library searching. High‐resolution filtering (HRF) was applied to confirm elemental formulas with sub‐1 ppm accuracy.

Main Results and Discussion

• PCA of technical replicates showed clear clustering by spirit type and origin, separating bourbon from Scotch and distinguishing regional styles.
• Volcano plots highlighted differential markers, notably elevated β-ionone in bourbon linked to higher beta‐carotene content of corn.
• Extracted ion chromatograms and box‐plots across sample groups confirmed consistent quantitative differences in key compounds.
• MS/MS confirmation and PCI experiments validated marker identities, including trans-β-ionone and hydroxymethyl furfural, with high mass accuracy and characteristic fragmentation.
• Comprehensive profiling yielded over 1,000 deconvoluted features, of which approximately 675 compounds were matched to spectral libraries with high confidence (SI > 700, HRF > 99%).

Benefits and Practical Applications

The Q Exactive GC system provides robust, high‐throughput chemical profiling suitable for routine quality assurance in the spirits industry. Its high mass resolution and accurate mass capabilities enable confident identification of major flavor compounds and trace adulterants. The workflow integrates easily accessible software tools for rapid data review and marker discovery, supporting product authenticity testing and flavor chemistry research.

Future Trends and Potential Applications

Emerging directions include expanding non‐targeted screening libraries, real‐time compliance monitoring, and integration of MS/MS workflows for deeper structural elucidation. The approach may be extended to other beverage matrices, combined with advanced chemometric methods and automated reporting pipelines to enhance throughput and reproducibility.

Conclusion

This proof‐of‐concept demonstrates that Orbitrap GC‐MS delivers comprehensive, high‐fidelity chemical profiles of whisky samples, distinguishing origin, age, and maturation conditions with sub‐ppm accuracy. The method offers a powerful tool for industry stakeholders to ensure quality, detect fraud, and explore flavor‐compound relationships.

References

• Scotch Whisky Association, 2015
• Distilled Spirits Council of the United States, 2015
• Nutritiondata.com (beta‐carotene content of grains)
• Thermo Scientific Application Note 10492