EA-IRMS: Tracking wine adulteration using isotope fingerprints

Importance of the Topic

Wine adulteration through sugar additions, water dilution and mislabeling poses significant risks to product integrity, regulatory compliance and consumer trust. Stable isotope fingerprinting offers a reliable approach to verify wine authenticity, detect illicit practices and uphold industry standards.

Objectives and Study Overview

This work demonstrates the application of combined carbon (δ13C), hydrogen (δ2H) and oxygen (δ18O) isotope ratio mass spectrometry (EA-IRMS) to ethanol extracted from wine. The aim is to identify exogenous sugar additions (chaptalisation) and water dilution by comparing isotopic signatures against a curated database of authentic European wines (EU-wineDB).

Methodology and Instrumentation

The analytical workflow integrates automated sample introduction and element-specific IRMS measurements:

• δ13C analysis: 1 µL purified ethanol injected via MAS 200R autosampler into a 1020 °C combustion reactor; resulting CO₂ analyzed on a DELTA V IRMS.
• δ2H and δ18O analysis: 0.1 µL ethanol introduced via AS 3000 autosampler into a 1450 °C pyrolysis reactor; H₂ and CO separated on a 5 Å molecular sieve GC at 70 °C and quantified against VSMOW and GISP standards.

Instrumentation Used:

• EA IsoLink IRMS System
• MAS 200R and AS 3000 autosamplers
• Thermo Scientific DELTA V IRMS
• Combustion and pyrolysis reactors; molecular sieve GC column

Key Results and Discussion

• Precision: δ13C ≤ 0.1 ‰; δ2H 0.12 ‰; δ18O 0.08 ‰ (1σ).
• Characteristic plant isotope ranges: C3 (–33 ‰ to –22 ‰), C4 (–16 ‰ to –8 ‰), CAM (–20 ‰ to –10 ‰).
• Pineapple ethanol (CAM source) exhibited δ13C = –14.32 ‰, confirming its distinct fingerprint.
• Shifts in isotopic values from authentic profiles indicate sugar or water additions, enabling adulteration detection.

Benefits and Practical Applications

• Definitive verification of wine origin and integrity.
• Detection of chaptalisation and unauthorized dilution.
• Support for regulatory compliance (EC No 607/2009) and protection of brand reputation.

Future Trends and Potential Uses

• Expansion of isotopic databases to include diverse vintages and global regions.
• Adoption of high-throughput EA-IRMS screening in routine quality control.
• Integration with elemental, molecular and spectroscopic markers for multi-dimensional authentication.
• Extension of methodology to other fermented beverages and agricultural products.

Conclusion

Multi-element stable isotope analysis via EA-IRMS delivers robust evidence of wine authenticity by exploiting high-precision δ13C, δ2H and δ18O fingerprints. This approach reliably detects exogenous sugar and water additions, reinforcing regulatory adherence and consumer confidence.

References

• Carter JF, Yates HSA, Tinggi U. Isotope composition of wine water. J Agric Food Chem. 2015;63:5771–5779.
• Rodrigues C, Maia R, Miranda M, et al. Regional isotope variations in wine water. J Food Compost Anal. 2009;22:463–471.
• O’Leary MH. Carbon isotope fractionation in plants. Bioscience. 1988;38:362–376.