WCPS: Elemental profiles of whiskies allow differentiation by type and region by inductively coupled plasma – optical emission spectroscopy (ICP-OES)

Significance of the Topic

Elemental profiling of whiskies provides a powerful approach for verifying origin, distinguishing styles, and understanding production influences. Trace and macro element patterns reflect raw materials, distillation equipment, and maturation processes, offering practical value in authentication and quality control.

Objectives and Study Overview

This study evaluated the elemental composition of 69 commercial whiskies to differentiate products by type and region. Sample set included:

• 33 single malt Scotch whiskies from six regions (Island, Islay, Lowland, Highland, Speyside, Campbeltown)
• 16 Bourbon, 8 Irish, 2 Tennessee, 1 American Rye, and 9 Japanese whiskies
• Ages ranging from 7 to 27 years

Data were analyzed using chemometric tools to assess classification potential.

Methodology and Instrumentation

Sample preparation and analysis:

• Dilution: 1:20 in 1% HNO₃, 0.5% HCl, and 4% ethanol
• Elemental quantification: 28 elements by direct introduction into ICP-OES with matrix-matched calibration standards, quality controls, and certified reference materials every ten samples
• Data processing: Agilent Mass Profiler Professional for exploratory data analysis and principal component analysis (PCA)

Used Instrumentation

Agilent 5100 ICP-OES featuring:

• CCD detector for rapid, wide-range spectral coverage
• Integrated Advanced Valve System (AVS) for efficient sample uptake and stabilization
• Dual View Sequential Configuration (DSC) for multiple operational modes
• Intuitive ICP Expert software with diagnostics and method development workflow

Main Results and Discussion

Analytical performance:

• Excellent linear calibration curves and wide concentration range for all elements
• Limits of detection in the low µg/L range
• Spike recovery within ±10% for most elements, confirming accuracy and precision

Chemometric findings:

• Box-whisker plots revealed distinct elemental patterns by age, type, and region
• PCA demonstrated separation of whisky classes, notably distinguishing Irish whiskies associated with higher Na, Ba, and Zn

Benefits and Practical Applications

This ICP-OES method offers high throughput, minimal reagent consumption, and robust sensitivity, making it suitable for routine QA/QC, product authentication, and style classification in the spirits industry.

Future Trends and Opportunities

Extending the element panel and integrating advanced multivariate techniques may further improve discrimination of whisky origins and maturation profiles. Collaboration with producers could refine chemometric models for regulatory authentication and deepen insights into production variables.

Conclusion

The Agilent 5100 ICP-OES platform proved effective for comprehensive elemental profiling across diverse whisky types. The method demonstrated reliable precision, rapid analysis, and strong potential to differentiate whiskies by style and provenance based on trace element signatures.