High precision Nd isotope ratio measurements

Significance of the Topic

Neodymium isotope ratio measurements are pivotal in geoscience research for tracing geological processes and understanding Earth's history. High precision and accuracy in these analyses enable reliable interpretation of sample origins and evolution.

Objectives and Study Overview

The study aimed to assess the performance of the Thermo Scientific Neoma MC-ICP-MS in measuring high precision Nd isotope ratios. Key goals included evaluating sensitivity, mass bias correction, interference control, and overall analytical precision compared to previous instrument generations.

Used Instrumentation

• Thermo Scientific Neoma MC-ICP-MS
• 100 µL/min self-aspirating nebulizer
• SIS spray chamber
• Faraday cup array with 10⁹ Ω and 10 Ω amplifiers
• 100 ppb Merck Nd standard solution

Methodology

Nd solution was introduced into the MC-ICP-MS at 100 µL/min. Isotope ratios were measured over ten 10-minute blocks with 8-second integration times. Exponential mass bias correction was applied using 146Nd/144Nd. Isobaric interferences from Ce and Sm were monitored simultaneously via the variable detector array. Static monitoring of 142Nd16O allowed tuning against oxide interferences.

Results and Discussion

• Sensitivity: 7.91 Gcps/ppm (127 V/ppm), ~2× higher than previous MC-ICP-MS models.
• Resolving power: ~1,950 across all cups, ensuring separation of Nd isotopes.
• Accuracy: Mean 143Nd/144Nd agreed within ±40 ppm of the accepted standard value.
• Precision: RSD better than 15 ppm for all reported ratios (e.g., 11 ppm for 142Nd/144Nd, 4 ppm for 143Nd/144Nd).

Benefits and Practical Applications

The enhanced sensitivity of the Neoma MC-ICP-MS reduces sample consumption by half while maintaining high precision, enabling high-throughput routine analyses. It supports geochemical tracing, environmental studies, and quality control in industrial laboratories.

Future Trends and Applications

• Expansion to other heavy isotope systems and coupling with laser ablation for spatial analysis.
• Integration of advanced data correction algorithms for complex matrices.
• Development of higher-resolution detectors for improved interference management.
• Applications in cosmochemistry, nuclear forensics, and environmental monitoring.

Conclusion

The Thermo Scientific Neoma MC-ICP-MS delivers unparalleled sensitivity and precision for Nd isotope ratio measurements in wet plasma mode. Its performance improvements facilitate lower sample usage, robust interference correction, and high analytical throughput, making it a valuable tool for geoscience and industrial applications.