Chemical Profiling of Whiskies Using Orbitrap GC-MS

Importance of the Topic

The chemical profile of whisky carries information about raw materials, fermentation and maturation, and is critical for quality control, authentication and origin verification. Comprehensive, untargeted analysis helps producers and regulators ensure product consistency, detect adulteration and understand flavor chemistry.

Objectives and Overview of the Study

This proof-of-concept work demonstrates a non-targeted, chemometric workflow for profiling complex whisky samples using a hybrid quadrupole-Orbitrap GC-MS system. Key aims were to detect compositional differences between single-malt and bourbon whiskies, to isolate discriminatory features, and to identify markers of origin or aging.

Methodology

Samples from two whisky types (single malt aged in three barrels and bourbon) underwent splitless injection (1 µL) on a 30 m x 0.25 mm TG-5SILMS column (0.25 µm film). GC separation was performed on a TRACE 1310 instrument, with full-scan data acquired on the Q Exactive GC Orbitrap at 60 000 FWHM (50–600 m/z) with sub-ppm mass accuracy. Data processing used SIEVE 2.2 for alignment, peak detection and statistical analysis, and PCA was applied to the pooled dataset.

Used Instrumentation

• Thermo Scientific TRACE 1310 GC with TraceGOLD TG-5SILMS column (30 m x 0.25 mm x 0.25 µm)
• Thermo Scientific Q Exactive GC Orbitrap MS
• Thermo Scientific TriPlus RSH autosampler
• TraceFinder and SIEVE 2.2 software for data extraction and chemometrics
• MassFrontier 7.0 for theoretical fragmentation and structure confirmation

Main Results and Discussion

PCA of all nine samples (four replicates each) revealed clear clustering of bourbon (sample 2295) and aged single malt (2265) versus other whiskies. A total of 4841 features (RT and exact mass) were detected. Elevated peaks in sample 2295 included m/z 177.1274 (RT 13.6 min), identified as trans-β-ionone via library match (98% spectrum fit). A second discriminatory peak at RT 18.0 min lacked a library hit; high-accuracy full-scan and PCI spectra yielded elemental compositions (C12H16O5) and adducts [M+H]+ and [M+C2H5]+. Mass accuracy (<1 ppm) and HR filtering reduced candidate formulas to a single match, 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid, which was confirmed via ChemSpider search and MassFrontier fragmentation.

Benefits and Practical Applications

• High mass resolution and sub-ppm accuracy enable confident identification of trace components without targeted methods.
• Fast full-scan GC-MS data acquisition supports untargeted profiling of complex beverages.
• Chemometric tools (PCA, feature extraction) isolate discriminating markers for authentication and quality control.

Future Trends and Applications

Scaling up to larger sample sets and integrating multi-dimensional separations (GC×GC) or complementary techniques (LC-HRMS) will deepen chemotypic understanding. Improved spectral databases, machine-learning-driven deconvolution and real-time screening platforms promise faster, more robust authentication workflows for spirits and other complex foods.

Conclusion

The Q Exactive GC Orbitrap GC-MS, combined with SIEVE and TraceFinder software, delivers high-throughput, untargeted chemical profiling with excellent mass accuracy and sensitivity. This approach successfully discriminated whisky types and identified key marker compounds, demonstrating its value for beverage authentication and compositional analysis.