Testing the Ce Limit of Mass Bias Correction Using ¹⁴⁵Nd/¹⁴²Nd as Normalizing Ratio in Radiogenic Neodymium Isotope...

Area of Science:

• Geochemistry
• Analytical Chemistry
• Mass Spectrometry

Background:

• Neodymium isotopes (Nd) are crucial geochemical tracers for Earth and extraterrestrial studies.
• Multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) enables precise 143Nd/144Nd ratio measurements.
• Traditional mass bias correction uses 146Nd/144Nd, but alternative methods using 145Nd/142Nd offer potential improvements, provided cerium (Ce) interference is managed.

Purpose of the Study:

• To evaluate the sensitivity of 145Nd/142Nd-based mass bias correction to varying Ce/Nd ratios.
• To compare the 145Nd/142Nd correction method with the conventional 146Nd/144Nd-based approach.
• To assess the impact of Ce contamination on Nd isotope data accuracy and precision.

Main Methods:

• Analysis of international Nd and rock reference materials using a Thermo Scientific Neptune Plus MC-ICP-MS.
• Systematic variation of Ce/Nd ratios in reference materials to simulate contamination.
• Comparison of 143Nd/144Nd results corrected using 145Nd/142Nd versus 146Nd/144Nd.

Main Results:

• Corrected 143Nd/144Nd ratios remained insensitive to Ce/Nd ratios up to approximately 1.
• The 145Nd/142Nd-based correction method demonstrated robustness against Ce interference.
• No significant degradation of Nd isotope data was observed even with substantial Ce presence.

Conclusions:

• The 145Nd/142Nd normalization method provides superior accuracy and precision for 143Nd/144Nd measurements compared to the 146Nd/144Nd method.
• This improved correction is effective even at high Ce/Nd levels (up to ~1).
• The method allows for better instrument tuning for higher signal intensity, particularly advantageous for low-Nd natural samples.