Optimized Data Integration Methods for Ultratrace-Level Pb Isotopic Analysis

A recent study published in the Journal of the American Society for Mass Spectrometry conducted an evaluation of the data integration methods for the isotopic analysis of lead (Pb) at ultratrace levels using thermal ionization mass spectrometry (TIMS) with a continuous heating method (1). This study was conducted by Jong-Ho Park and his team from Jeonbuk National University.

Ingots made of lead. Generated with AI. | Image Credit: © 2ragon - stock.adobe.com

For the experimental evaluations, the research team used a Pb certified reference material SRM 981. The evaluations were designed by the research team to review the efficacy of several data calculation methods and integration ranges (1).

The study revealed that Method I, which calculated the isotope ratios based on summed ion signal intensities compensating for mass fractionation, demonstrated exceptional consistency with certified values for 10 and 1 ng standard samples across all integration ranges (1). Even for 100 pg samples, full range calculations occasionally faltered, but reduced ranges (over 1%, 25%, and 75%) yielded values overlapping with certified ones, underscoring the robustness of Method I (1).

It was the opposite case with Method II. Relying on averaged precalculated isotope ratios, Method II demonstrated inferior performance (1). On the other hand, Method III was competitively like Method I. Method III, which utilized weighted averaging to mitigate anomalous values, showed promising results consistent with Method I, although the conclusion the researchers drew was that Method III is best suited primarily for single measurements (1).

Based on the results of the study, the researchers conclude that an integration range of over 1% or 25% is needed to exclude anomalies while compensating for mass fractionation (1). Doing so will ensure that accuracy and precision in ultratrace-level Pb isotopic analysis using TIMS is optimized (1). The optimized method was validated by comparing results from two different instruments used for the isotopic analysis of the reference material, affirming its enhanced accuracy and precision (1).

The evaluation conducted by Park and colleagues not only advances our understanding of Pb isotopic analysis, but it also paves the way for more precise and reliable measurements in diverse applications ranging from environmental monitoring to forensic investigations (1).

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Reference

(1) Park, Y.-S.; Lee, K.-S.; Lim, J. S.; Park, J.-H. Isotopic Analysis of Lead at Ultratrace Levels Using Thermal Ionization Mass Spectrometry (TIMS) Coupled with the Continuous Heating Method: Optimization of the Data Integration Range and Method. J. Am. Soc. Mass Spectrom. 2024, 35 (1), 158–165. DOI: 10.1021/jasms.3c00390