EA-IRMS: Tracking wine adulteration using isotope fingerprints

Importance of the Topic

Adulteration of wine through addition of external sugars, water or cheaper juices affects product authenticity, consumer trust and regulatory compliance. Stable isotope analysis provides a robust tool to confirm origin and detect fraudulent practices in wine production.

Objectives and Study Overview

This application brief aims to demonstrate multi-element isotope fingerprinting of ethanol from wine using an Elemental Analyzer-Isotope Ratio Mass Spectrometry (EA-IRMS) approach. By measuring carbon, hydrogen and oxygen isotope ratios, the study evaluates the potential to identify chaptalisation and water addition and to support compliance with EU regulation EC No 607/2009 using a reference wine database.

Methodology

Samples of purified ethanol from wines and sugar-enriched model mixtures were introduced into an EA-IRMS system. Carbon isotope ratio (δ13C) was determined by combusting 1 μL ethanol in a tin capsule at 1020 °C and measuring the resulting CO2 on a DELTA V IRMS. Hydrogen and oxygen ratios (δ2H, δ18O) were measured by pyrolysis of 0.1 μL ethanol at 1450 °C, separating H2 and CO on a molecular sieve GC column and analyzing on IRMS. Results were referenced to VSMOW and GISP standards.

Used Instrumentation

• Thermo Scientific EA IsoLink IRMS System
• MAS 200R Autosampler (for δ13C)
• AS 3000 Autosampler (for δ2H, δ18O)
• DELTA V Isotope Ratio Mass Spectrometer
• Pyrolysis and Combustion Reactors

Results and Discussion

Precision for δ13C, δ2H and δ18O measurements was better than 0.1‰, 0.12‰ and 0.08‰, respectively. Ethanol from pineapple juice displayed a CAM plant fingerprint (δ13C ≈ -14.3‰). Sugar-enriched wine samples showed elevated δ13C values consistent with C4 plant sources, distinguishing them from authentic C3 grape ethanol (δ13C between -33‰ and -22‰). These isotopic offsets allow reliable detection of exogenous sugar addition and water dilution.

Practical Benefits and Applications

• Verification of wine authenticity by comparing isotopic fingerprints against certified wine-DB values
• Detection of chaptalisation and water addition in commercial wines
• Support for regulatory compliance with EU wine labeling laws
• Protection of brand reputation and consumer confidence

Future Trends and Applications

Advances in high-throughput EA-IRMS automation and expansion of international isotopic databases will enhance routine screening capacity. Integration with multivariate statistical tools and machine learning may improve origin assignment and highlight subtle adulteration patterns. Coupling with other spectroscopic or chromatographic methods can further refine authentication workflows.

Conclusion

This study confirms that automated multi-element isotope fingerprinting of ethanol provides a precise, reproducible approach to detect wine adulteration and verify geographical origin. The method supports industry and regulatory needs for reliable authenticity testing and can be widely applied in quality control laboratories.

References

• Carter J.F., Yates H.S.A., Tinggi U. (2015) Journal of Agricultural and Food Chemistry 63:5771–5779.
• Rodrigues C., Maia R., Miranda M., Ribeirinho M., Nogueira J.M.F., Aguas C.M. (2009) Journal of Food Composition Analysis 22:463–471.
• O’Leary M. (1988) Bioscience 38:329–326.