EA-IRMS: Tracing geographical origin of Argan oil using carbon and oxygen isotope fingerprints

Significance of the Topic

Argan oil is a high-value product with protected geographical indication due to its economic, social, and environmental roles in Morocco. Guaranteeing its authenticity protects both producers from fraud and consumers from mislabeled or adulterated products.

Objectives and Study Overview

This study demonstrates the ability of carbon (δ13C) and oxygen (δ18O) isotope fingerprinting using EA-IRMS to trace the geographic origin of Argan oil. A total of 47 samples from key Moroccan regions were analyzed to establish isotopic baselines and evaluate differentiation by region.

Methodology

• Sample preparation: 0.3 mg Argan oil in tin capsules for carbon analysis; 0.6 µL in silver capsules for oxygen analysis.
• EA-IRMS workflow: Combustion reactor for CO₂ production; pyrolysis reactor at 1450 °C for CO gas generation.
• Analysis times: 400 s for carbon isotope ratio; 530 s for oxygen isotope ratio.

Instrumentation Used

• Thermo Scientific™ EA IsoLink™ IRMS System
• Thermo Scientific™ MAS Plus Autosampler

Main Results and Discussion

• δ13C values correlated with humidity and proximity to the coast: regions like Essaouira and Agadir showed more negative δ13C due to higher humidity.
• δ18O values varied with altitude and inland distance: higher-altitude samples exhibited enriched δ18O, while coastal regions (Essaouira, Chtouka) had lower δ18O.
• Combined δ13C and δ18O plot revealed distinct clusters by region, reflecting environmental factors such as rainfall patterns, altitude, temperature, and soil characteristics.

Benefits and Practical Applications

• Provides a robust, rapid tool for verifying the provenance of Argan oil and detecting adulteration.
• Supports regulatory control and quality assurance in food, cosmetic, and pharmaceutical industries.
• Enhances consumer confidence and protects the reputation of regional producers under PGI status.

Future Trends and Opportunities

• Extension of isotope databases to include hydrogen isotopes for finer geographic resolution.
• Integration with other analytical techniques (e.g., NMR, chromatography) for multimodal authentication workflows.
• Development of portable or field-deployable IRMS systems for on-site screening.

Conclusion

Carbon and oxygen isotope fingerprinting via EA-IRMS effectively distinguishes Argan oil origins across Moroccan regions. The approach enhances traceability, safeguards product integrity, and supports efforts against economically motivated fraud.

References

• Taous F, Amenzou N, Marah H, et al. Forensic Chemistry. 2020;17.
• Camin F, Bontempo L, Ziller L, et al. Rapid Communications in Mass Spectrometry. 2010;24(12).
• Dansgaard W. Tellus. 1964;16.