EA-IRMS: Tracing the geographical origin of cocaine

Importance of the topic

Cocaine remains one of the most prevalent illicit substances worldwide, driving the need for precise methods to track cultivation areas and distribution routes. Stable isotope analysis offers a noninvasive forensic approach to link seized samples back to their geographic origin, aiding law enforcement and intelligence operations.

Study objectives and overview

This application brief summarizes the work by Mallette et al. (2016), which established isotope fingerprint data from 572 coca leaf samples across 19 growing regions in Bolivia, Colombia and Peru. The primary aim was to demonstrate how carbon, nitrogen, hydrogen and oxygen isotope ratios in both coca leaves and seized cocaine can pinpoint production regions at sub-regional scales.

Methodology

Sample preparation involved weighing 0.9–1.2 mg of cocaine into tin capsules for δ13C and δ15N analysis and 0.20–0.25 mg into silver capsules for δ2H and δ18O analysis. Combustion and pyrolysis were performed using an EA-IRMS system at 1400 °C. Calibration employed internationally recognized standards: Vienna Pee Dee Belemnite (VPDB) for carbon, AIR for nitrogen, Vienna Standard Mean Ocean Water (VSMOW) for hydrogen and oxygen.

Used instrumentation

• Elemental Analyzer–Isotope Ratio Mass Spectrometer (EA-IRMS) system
• Pyrolysis reactor maintained at 1400 °C
• Secondary and primary isotope standards (C-28, C-34, atropine, benzoic acid, IAEA-601)

Main results and discussion

Isoscapes for δ13C, δ15N and δ2H across Colombian coca leaves revealed distinct geographic patterns influenced by altitude, climate and soil. Combining isotope fingerprints with trace alkaloid profiles and multivariate statistics enabled high-confidence assignment of seized cocaine to one of the 19 defined regions. A noteworthy case involved identifying a previously unreported coca cultivation area in Beni, Bolivia, following analysis of a cocaine seizure in Uruguay.

Benefits and practical applications

• Enhanced resolution for tracing cocaine origin down to sub-regional levels
• Support for law enforcement investigations and intelligence gathering
• Ability to discover new or emerging cultivation zones
• Complementary use alongside alkaloid profiling for robust classification

Future trends and possibilities of application

Advancements may include expanding isotope databases to cover more regions, integrating additional isotope systems (e.g., sulfur), employing real-time portable IRMS for field analysis, and applying similar approaches to other controlled substances or wildlife forensics.

Conclusion

Bulk stable isotope analysis via EA-IRMS provides a powerful forensic tool to trace the geographic origin of cocaine with sub-regional specificity. The methodology’s success in identifying both known and previously unknown cultivation areas highlights its value for global drug enforcement strategies.

References

• Mallette JR, Casale JF, Jordan J, Morello DR, Beyer PM. Geographically Sourcing Cocaine’s Origin – Delineation of the Nineteen Major Coca Growing Regions in South America. Sci Rep. 2016;6:23520.
• Rodrigues C, Brunner M, Steiman S, Bowen GJ, Nogueira JMF, Prohaska T, Máguas C. Carbon and hydrogen isotopes in coca leaves vary with geography and cultivation. J Agric Food Chem. 2011;59:10239–10246.
• Carter JF, Yates HSA, Tinggi U. Regional δ2H and δ18O variations in Colombia: implications for cocaine provenance. J Agric Food Chem. 2015;63:5771–5779.
• Rodrigues C, Maia R, Miranda M, Ribeirinho M, Nogueira JMF, Máguas CM. Environmental controls on leaf water isotope composition in coca plants. J Food Comp Anal. 2009;22:463–471.