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

Importance of the Topic

The global demand for Argan oil in pharmaceutical, food and cosmetic industries continues to grow, driven by its unique nutritional and functional properties.
As a Protected Geographical Indication (PGI) product endemic to south-western Morocco, authentic tracing of its origin is critical to prevent fraud, protect local producers and maintain consumer confidence.

Objectives and Study Overview

This study aimed to demonstrate how carbon (δ13C) and oxygen (δ18O) isotope fingerprints obtained by Elemental Analysis-Isotope Ratio Mass Spectrometry (EA-IRMS) can distinguish the geographical origin of Argan oil.
A total of 47 oil samples were collected from six Moroccan regions (Essaouira, Agadir, Chtouka, Taroudant, Tiznit, Sidi Ifni) and analyzed for their bulk isotope values.

Methodology and Instrumentation

• Samples for carbon analysis: 0.3 mg of Argan oil weighed into tin capsules; combusted to CO₂; analyzed by Thermo Scientific EA IsoLink IRMS system; run time ~400 s.
• Samples for oxygen analysis: 0.6 μL of oil in silver capsules; pyrolyzed at 1450 °C to CO; analyzed by EA IsoLink IRMS; run time ~530 s.

Main Results and Discussion

• δ13C values correlate with regional humidity and proximity to the Atlantic coast: more negative values in humid coastal zones (Essaouira, Agadir), less negative in arid inland areas (Taroudant).
• δ18O values reflect altitude and hydrological patterns: lower values near the coast, higher values at greater elevation behind the High Atlas barrier.
• Combining δ13C and δ18O in a bivariate plot enhances discrimination of sample origin, revealing distinct clustering by region based on climatic and geographical factors.

Benefits and Practical Applications

• Provides a robust analytical framework for verifying PGI status and detecting adulteration or mislabeling.
• Supports quality assurance, regulatory compliance and supply chain authentication in food, cosmetic and pharmaceutical sectors.
• Helps safeguard producer reputation and consumer trust by ensuring traceability of high-value natural products.

Future Trends and Opportunities

• Integration of additional isotopic markers (e.g., hydrogen, nitrogen) and elemental profiles for multi-parameter provenance models.
• Expansion of regional and temporal databases to account for harvest year variability and climate change effects.
• Application of chemometric and machine learning tools for automated classification and improved origin prediction.
• Development of portable or field-deployable IRMS platforms for on-site screening and rapid authenticity checks.

Conclusion

Carbon and oxygen isotope analysis by EA-IRMS offers a powerful, reproducible method to trace the geographical origin of Argan oil and combat economically motivated fraud. By exploiting natural climatic and environmental signatures, this approach strengthens authenticity control, supports PGI enforcement and enhances consumer protection.

References

1. Taous F, Amenzou N, Marah H, Maia R, Maguas C, Bahmad L, Kelly S. Forensic Chemistry. 2020;17.
2. Camin F, Bontempo L, Ziller L, Piangiolino C, Morchio G. Rapid Communications in Mass Spectrometry. 2010;24(12).
3. Dansgaard W. Tellus. 1964;16.