TIMS: Accuracy of La Jolla Nd Isotopic Data Acquired Using the Thermo Scientific TRITON Plus TIMS

Importance of Nd Isotopic Analysis

Neodymium isotopic measurements at parts-per-million precision are fundamental for constraining timescales and processes in geochronology, geochemistry, cosmochemistry and environmental studies. High-precision Nd data enable tracing of crustal formation, mantle differentiation and ancient extraterrestrial materials, making robust analytical methods essential for research and quality assurance workflows.

Objectives and Study Overview

This study assesses the accuracy and reproducibility of Nd isotope ratios obtained on Thermo Scientific TRITON Plus TIMS using the La Jolla Nd reference standard. The focus is on resolving ppm-level isotopic anomalies in 500 ng Nd loads with a rapid static analysis employing a virtual amplifier configuration.

Methodology and Instrumentation

The analytical protocol combines zone-refined rhenium double filaments and static multi-collector acquisition with amplifier-cup rotation. Key parameters include:

• Reference standard: La Jolla Nd (144Nd = 1.1418387 ± 0.0000102, 2 SD)
• Filament outgasing: 40 min at 3.2 A, 10 min at 4.5 A
• Sample loading: 500 ng Nd in 6 M HCl with 1 µL 0.3 M H3PO4 additive
• Ionization temperature: 1650 °C
• Acquisition mode: static with virtual amplifier, three rotation cycles (480 ratios)
• Amplifiers: 1011 Ω resistors and Faraday cups
• Baseline integration: 105 s prior to each block

Results and Discussion

Analyses of the La Jolla standard yield a 142Nd/144Nd ratio of 1.1418357 ± 0.00000046 (2 SD), matching literature values within uncertainty. External reproducibility of ~2 ppm/amu is achieved in under 90 minutes per run, roughly twice the speed reported in earlier studies. Stable operation of the virtual amplifier and Faraday cup system supports consistent multi-collector performance.

Benefits and Practical Applications

This optimized TIMS workflow offers rapid, high-precision Nd isotope data suitable for routine laboratory use in geochemical investigations, cosmochemical sample screening and environmental tracer studies. The method enhances sample throughput while maintaining stringent precision requirements for research and QA/QC applications.

Future Trends and Opportunities

Future developments include adoption of the JNdi-1 standard for improved inter-laboratory comparability, further amplifier electronics refinement and automated sample handling. Advancements may extend precision to lower Nd loads and expand applications in micro-analysis and in situ studies.

Conclusion

The TRITON Plus TIMS static virtual amplifier method delivers accurate Nd isotope ratios with external reproducibility of 2 ppm/amu in under 90 minutes. Results align with established reference data, validating the technique for high-throughput, high-precision isotopic analyses.

References

1. Caro M, Bourdon B, Telouk P et al. 2003 Nature 423, 428–432.
2. Boyet M, Carlson RW. 2005 Science 309, 576–581.
3. Trinquier A. Thermo Scientific Application Note 30280.
4. O’Neil JR, Gaffney AM, Jackson MG et al. 2008 Science 321, 1828–1831.
5. Tanaka T, Amakawa H, Kajii Y. 2000 Chemical Geology 168, 279–281.