Optimisation of a current generation ICP-QMS and benchmarking against MC-ICP-MS spectrometry for the determination of lead isotope ratios in environmental samples

Abida Usman,Vanessa Pashley,Scott D Young,Elizabeth H Bailey,Simon R Chenery,Simon Nelms,E Louise Ander

doi:10.1039/c8ja00290h

Abstract

Novel ANOVA methodology was used to benchmark ICP-QMS against MC-ICP-MS for Pb isotope ratios, demonstrating “fitness-for-purpose” in source apportionment.

Highlights

Lead isotopes can be measured by a range of mass spectrometry techniques
Coupled plasma mass spectrometers (ICP-MS) are more appropriate for routine use with large sample numbers and are operationally simpler than thermal ionization mass spectrometry (TIMS) [5]; sample introduction is at atmospheric pressure and ionization of most elements is readily achieved
Following optimisation of the Pb isotopic ratios measurement protocol, the processed data for diluted soil sample digests analysed with ICP-QMS (10,000 scans) were compared to equivalent data for chemically separated Pb measured by MC-Inductively coupled plasma mass spectrometers (ICP-MS)

Summary

Introduction

Lead isotopes can be measured by a range of mass spectrometry techniques. Until fairly recently, thermal ionization mass spectrometry (TIMS) was the preferred choice for precise (0.001-0.01% RSD)measurement of Pb isotope abundances [1, 2]. TIMS involves laborious sample preparation steps, such as separation of the analyte from the matrix into a highly purified form, involving extensive chemical treatment, and stringent optimisation of vaporisation and ionisation conditions of samples, with long analysis times (~45 minutes) These measurements are time consuming and incur cost, rendering TIMS unsuitable when analysing large numbers of samples [3, 4]. Coupled plasma mass spectrometers (ICP-MS) are more appropriate for routine use with large sample numbers and are operationally simpler than TIMS [5]; sample introduction is at atmospheric pressure and ionization of most elements is readily achieved They are widely used for multi-element and isotopic analysis and are routinely capable of a precision (

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