EA-IRMS: Characterizing Himalayan rice of different origin by oxygen and hydrogen isotope fingerprints

Importance of the Topic

Rice is a staple food for much of the global population, with aromatic varieties like basmati commanding high market value. Mislabeling and adulteration of premium rice threaten consumer trust and producer reputation. Stable isotope fingerprinting of oxygen and hydrogen offers a reliable method to trace rice provenance and enforce product labeling regulations.

Objectives and Study Overview

This study aimed to demonstrate how oxygen and hydrogen isotope ratios can differentiate Himalayan rice samples by geographical origin. A total of 69 rice samples from two distinct altitude regions were analyzed to establish isotope-based provenance markers.

Methodology and Analytical Configuration

The analytical workflow included:

• Sample preparation: ~2 mg of ground rice dried at 80 °C overnight to remove moisture, then sealed in silver capsules.
• Combustion: Capsules introduced via the MAS Plus autosampler into the EA IsoLink combustion reactor to generate CO and H₂ gases.
• Detection: Evolved gases analyzed by the DELTA V isotope ratio mass spectrometer.
• Throughput: Each sample required approximately 450 seconds under full automation.

Used Instrumentation

• Thermo Scientific EA IsoLink IRMS System
• Thermo Scientific MAS Plus Autosampler
• Thermo Scientific DELTA V Isotope Ratio Mass Spectrometer

Key Results and Discussion

Data plotted in a two-dimensional δ2H vs. δ18O space revealed two distinct clusters corresponding to the two altitude-based growing regions. Samples from the higher-altitude region showed lower mean values (δ2H: –67‰, δ18O: 27.1‰) compared to the lower-altitude group (δ2H: –62‰, δ18O: 28.7‰). These trends align with global meteoric water line behavior and underscore the influence of local rainfall and groundwater isotopic composition on plant water uptake.

Benefits and Practical Applications

• Provides a robust analytical framework to verify rice geographic origin and detect mislabeling.
• Supports compliance with food labeling regulations (e.g., EC Reg. No. 1169/2011, FDA standards).
• Enhances quality assurance and anti-fraud measures for high-value agricultural commodities.
• Delivers fast, automated, and reliable results suitable for routine laboratory workflows.

Future Trends and Applications

Further developments may include integrating multiple stable isotope systems (C, N, S) with elemental profiling to build comprehensive provenance databases. Expanding isotope fingerprint libraries for diverse agricultural products will strengthen global QA/QC frameworks and support advanced anti-fraud strategies.

Conclusion

Oxygen and hydrogen isotope analysis using the EA IsoLink IRMS System successfully discriminates rice origin by altitude-driven isotopic variation. This automated approach offers laboratories a powerful tool for detecting adulteration, safeguarding brand integrity, and maintaining consumer confidence.

References

1. Kelly S, Baxter M, Chapman S, Rhodes C, Dennis J, Brereton P. The application of isotopic and elemental analysis to determine the geographical origin of premium long grain rice. European Food Research and Technology. 2002;214(1):72-78.
2. Suzuki Y, Chikaraishi Y, Ogawa N, Ohkouchi N, Korenaga T. Geographical origin of polished rice based on multiple element and stable isotope analyses. Food Chemistry. 2008;109(2):470-475.
3. Chung IM, Kim JK, Prabakaran M, Yang JH, Kim SH. Authenticity of rice (Oryza sativa L.) geographical origin based on analysis of C, N, O and S stable isotope ratios: a preliminary case report in Korea, China and Philippine. Journal of Science of Food and Agriculture. 2016;96(7):2433-2439.