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

Significance of Topic

Resolving neodymium isotopic anomalies at ppm levels underpins advances in geochronology, geochemistry, cosmochemistry and environmental science. High precision Nd isotope data reveal subtle fractionation processes, source characteristics and temporal evolution of natural archives. Enhanced accuracy and throughput in Nd isotope analysis support robust interlaboratory comparisons and broad application across research and quality control laboratories.

Objectives and Study Overview

This study evaluates the accuracy and reproducibility of 500 ng Nd+ analyses of the La Jolla standard on a Thermo Scientific TRITON Plus Thermal Ionization Mass Spectrometer in static mode with virtual amplifier. Building on prior reproducibility assessments, the goal is to validate rapid isotopic measurements and confirm agreement with established reference values.

Methodology and Instrumentation

Sample preparation and analysis followed a standardized TIMS protocol for Nd static mode analysis with virtual amplifier

• Isotopic standard: La Jolla Nd with certified 142Nd144Nd ratio of 1.1418387 ± 102 (2SD)
• Filament assembly: zone refined rhenium double filaments
• Outgassing: 40 min at 3.2 A then 10 min at 4.5 A
• Sample load: 500 ng Nd in 6 M HCl with 1 µL 0.3 M H3PO4 additive and brief red glow activation
• Acquisition: static mode using 1011 Ω amplifiers and virtual amplifier rotation (3 cycles, 480 ratios)
• Baseline measurement: 105 s prior to each block
• Temperature: maintained at 1,650 °C on ionization filament
• Mass bias correction: exponential normalization to 146Nd144Nd = 0.7219

Main Results and Discussion

Analyses of the La Jolla standard achieved external reproducibility of 2 ppm/amu (2SD) on 500 ng loads with no statistical outliers. The measured 142Nd144Nd ratio of 1.1418357 ± 46 matches literature values within uncertainty. Instrument performance remained stable over repeated cycles, and static mode with virtual amplifier reduced analysis time to under 90 minutes without compromising precision.

Benefits and Practical Applications

Rapid, high-precision Nd isotope measurements enable:

• Efficient throughput for routine laboratory workflows
• Improved interlaboratory consistency using robust reference standards
• Enhanced ability to track isotopic variations in geological and environmental samples

Future Trends and Potential Applications

Advances may include broader adoption of high-impedance amplifiers and automated filament handling for further time savings. The use of internationally certified standards such as JNdi-1 will refine accuracy across laboratories. Integration with multi-collector ICP-MS and laser ablation systems may expand spatially resolved Nd isotope mapping in complex matrices.

Conclusion

This study demonstrates that static mode TIMS with virtual amplifier on the TRITON Plus delivers rapid Nd isotope analysis at 2 ppm/amu reproducibility. Results for the La Jolla standard align with established values, validating instrument stability and supporting routine high-precision Nd isotopic applications.

References

• Caro et al 2003 Nature 423 428-432
• Boyet and Carlson 2005 Science 309 576-581
• Trinquier Thermo Scientific Application Note 30280
• ONeil et al 2008 Science 321 1828-1831
• Tanaka et al 2000 Chem Geol 168 279-281