Isotope Analysis of Water, Fruit Juice and Wine Using the Thermo Scientific GasBench II IRMS

Importance of the Topic

Oxygen isotope ratios (18O/16O) are widely used to trace hydrological processes, verify authenticity of beverages, and monitor metabolic pathways. Accurate, high-throughput methods are essential for research in environmental science, food quality control, and clinical studies.

Objectives and Overview of the Study

This study evaluates the Thermo Scientific GasBench II continuous flow interface coupled to an IRMS for precise 18O/16O determination in water, fruit juice, and wine. It compares results against the dual inlet HDO II equilibrator, demonstrating the system’s performance across diverse sample matrices.

Methodology

Sample preparation employs acid-washed borosilicate vials, automated He-CO2 flushing to remove air, and isotopic equilibration of a small CO2 headspace with the liquid sample at controlled temperature. Repetitive loop injections into a GC column separate CO2 for IRMS measurement, achieving replicate precision comparable to dual inlet systems.

Instrumentation Used

• Thermo Scientific GasBench II IRMS with autosampler and continuous flow interface
• Thermo Scientific DELTA V Advantage and DELTA V Plus IRMS
• Thermo Scientific HDO II water equilibrator (dual inlet peripheral)
• Gas chromatograph with PoraPLOT Q column

Main Results and Discussion

• Water standards showed excellent agreement with HDO II (<0.04‰ offset) and external precision <0.05‰; no memory effects detected even for depleted Antarctic samples.
• Fruit juice analysis detected water dilution in orange juices, with precision <0.06‰ and clear discrimination against local water baselines.
• Wine authenticity tests matched HDO II data within 0.03‰. Direct analysis of natural CO2 in wine eliminated the need for added CO2, maintaining precision ~0.035‰.

Benefits and Practical Applications

• High precision and small sample volumes (down to 50 µL) enable efficient isotope studies in hydrology, food fraud detection, and metabolic research.
• Continuous flow operation with autosampler support increases throughput and reduces per-sample preparation time.

Future Trends and Potential Applications

Advances may include further miniaturization of sample volumes, integration with novel IRMS platforms for enhanced sensitivity, and streamlined protocols exploiting native CO2 in beverages. Expansion of continuous flow isotope analysis into routine quality control and field-deployable systems is anticipated.

Conclusion

The GasBench II IRMS provides a robust, high-throughput alternative to dual inlet systems for 18O/16O analysis in aqueous matrices and beverages. Its validated accuracy, precision, and flexibility support a broad range of scientific and industrial applications.

References

• Nelson ST. Rapid Commun. Mass Spectrom. 14:1044–1046 (2000)
• Nelson ST. Rapid Commun. Mass Spectrom. 14:293–297 (2000)