Extra high resolution option for MC-ICP-MS

Significance of the Topic

High-resolution separation of polyatomic hydride interferences is essential for precise MC-ICP-MS isotope ratio analyses. Hydride species such as 40Ar1H+ can overlap target isotopes like 41K+, limiting accuracy in geochemistry, planetary science, agricultural tracing, and biomedical research.

Objectives and Study Overview

This study evaluates the Thermo Scientific Neptune XT MC-ICP-MS equipped with the XHR Extra High Resolution option, which achieves resolving power above 15,000. The primary aim is to resolve hydride interferences and improve the precision and accuracy of 41K/39K measurements.

Methodology

Potassium was purified by high-pressure ion chromatography and diluted to 2 μg/g in 3 wt.% HNO3. Samples were introduced via an Elemental Scientific apex Ω desolvation system with 25 mL/min N2 to suppress 40Ar+ and 40ArH+. Data were acquired by sample-standard bracketing with 3 minute integrations.

Used Instrumentation

• Thermo Scientific Neptune XT MC-ICP-MS with XHR Extra High Resolution option (resolving power >15,000)
• Elemental Scientific apex Ω high sensitivity desolvation system with N2 addition
• Thermo Scientific Dionex ICS-5000+ Capillary HPIC for potassium purification
• Standard cones, 1200 W RF power, Faraday cups and relay matrix collection

Main Results and Discussion

Mass scans at the 41K+ peak exhibit a resolving power of ~18,000, clearly separating 41K+ from 40Ar1H+. External precision for δ41K achieved 2SD comparable to literature values. Simultaneous alignment of 39K+ and 41K+ collectors produced broad, interference-free plateaus, demonstrating quantitative removal of hydride overlaps.

Benefits and Practical Applications

• Improved accuracy in potassium isotope geochemistry and planetary sample analysis
• Enhanced precision for Mg, Si, and Cl isotope systems affected by hydride interferences
• Potential applications in agricultural and biomedical isotope tracing

Future Trends and Opportunities

Future developments may focus on further optimization of hydride-suppression strategies, automated sample introduction, and extension of XHR capabilities to Fe, Cr, and other challenging isotopic systems. Integration with advanced data analytics will expand high-precision isotope applications.

Conclusion

The XHR Extra High Resolution option for Neptune XT delivers >15,000 resolving power with ≥1% transmission, effectively separating polyatomic hydride interferences and enabling precise δ41K determinations. This advance broadens the applicability of MC-ICP-MS in research and industrial quality control.

References

1. Lloyd N, Field P, Morgan L, Santiago Ramos D, Higgins J (2017) Goldschmidt Abstracts 2439.
2. Leah E. Morgan et al. (2017) High-precision potassium isotope measurements, DOI: 10.1039/c7ja00257b.