WDSC 2017: Chemical profiling of whiskies using Orbitrap GC-MS

Significance of the topic

Detailed chemical profiling of whisky is crucial for product authentication, quality control and flavor characterisation in the spirits industry. High resolution analytical techniques enable detection of unique markers and adulterants.

Objectives and overview

This proof of concept study evaluated a non targeted workflow using an Orbitrap GC MS platform to profile nine whisky samples from different origins. The aim was to apply full scan data acquisition and chemometric analysis to reveal compositional differences and propose compound identities.

Methodology and used instrumentation

Whisky samples were prepared by liquid liquid extraction into ethyl acetate and a pooled quality control sample was generated. Each extract was injected in quadruplicate in random order.

• Gas chromatography performed on Thermo Scientific Trace 1310 GC with TraceGOLD TG 5SILMS column (30 m × 0.25 mm × 0.25 μm), splitless injection and helium carrier gas
• Mass spectrometry using Thermo Scientific Q Exactive GC hybrid quadrupole Orbitrap at 60 000 FWHM over 50–600 m/z with internal lockmass
• Data processing conducted with TraceFinder for deconvolution and spectral matching and Sieve 2.2 for peak alignment, detection and principal component analysis

Main results and discussion

High resolution full scan acquisition delivered consistent sub ppm mass accuracy, enabling confident compound detection. Principal component analysis clearly separated bourbon and single malt whiskies based on unique chemical profiles. Trans β-ionone was identified as a distinguishing marker at retention time 13.6 minutes through accurate mass filtering and EI spectral matching. An unknown peak at 18.0 minutes was further characterised by combining EI and PCI spectra to propose an elemental formula.

Benefits and practical applications

• Comprehensive untargeted profiling of complex spirit matrices
• Rapid differential analysis using advanced chemometric workflows
• High confidence compound identification with sub ppm mass accuracy
• Support for quality assurance, authenticity verification and product development

Future trends and potential applications

Expanding the sample set will improve robustness of whisky fingerprinting. Integration with high-throughput screening methods and additional ionisation modes could enhance marker discovery. Applying machine learning to large datasets may advance predictive authentication models.

Conclusion

The Q Exactive GC Orbitrap platform demonstrates powerful capabilities for untargeted chemical profiling of whisky, combining high resolution accurate mass data with robust chemometric analysis. Future work with broader sample diversity will further validate its role in spirits authentication and quality control.