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

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


Abida Usman

Principal Research Fellow

Professor of Environmental Geochemistry

Simon Nelms

Vanessa Pashley

Scott D. Young

Simon R. Chenery


© 2018 The Royal Society of Chemistry. Novel ANOVA methodology was used to benchmark ICP-QMS against MC-ICP-MS for Pb isotope ratios, demonstrating "fitness-for-purpose" in environmental source apportionment. The precision and accuracy of lead (Pb) isotope measurements obtained from quadrupole-based mass spectrometers (ICP-QMS) are considered to be limited by a number of factors originating in different components of the instruments. In this study, experimental and instrumental protocols were optimised for determining lead isotope ratios in urban soil digests. Experimental measures included individual dilution of all samples and isotopic standards (SRM-981, NIST) to a single Pb concentration intended to produce an intensity which was high enough to negate blanks and interferences but low enough to ensure the detector operated only in pulse counting mode. Instrumental protocols included batch dead time correction, optimisation of dwell time and the number of scans employed and correction of mass discrimination by sequential application of both internal ( 203 Tl/ 205 Tl ratio) and external (SRM-981, NIST) standards. This optimised methodology was benchmarked against multi-collector mass spectrometer (MC-ICP-MS) measurements of Pb isotope ratios using replicate digest solutions of the same soil; but after these had been subjected to Pb separation using an ion-exchange procedure. On the assumption that MC-ICP-MS measurements are more accurate, small additive and multiplicative differences were observed in only the 4 th decimal place. ANOVA was used to compare the precisions of the two techniques demonstrating equal precisions c. 0.08% for 207 Pb/ 206 Pb, suggesting a sample heterogeneity limitation. By contrast, for 207 Pb/ 204 Pb, the worst-case ratio, ICP-QMS had a 10-fold poorer precision, despite negligible interference from 204 Hg, implying an instrumental limitation. The study concludes that ICP-QMS can provide valuable source apportionment information for most Pb isotope ratios but further efforts should focus on improving assay of the 207 Pb/ 204 Pb ratio.


Usman, A., Ander, E. L., Bailey, E. H., Nelms, S., Pashley, V., Young, S. D., & Chenery, S. R. (2018). Optimisation of a current generation ICP-QMS and benchmarking against MC-ICP-MS spectrometry for the determination of lead isotope ratios in environmental samples. Journal of Analytical Atomic Spectrometry, 33(12), 2184-2194.

Journal Article Type Article
Acceptance Date Nov 5, 2018
Online Publication Date Nov 12, 2018
Publication Date Dec 1, 2018
Deposit Date Dec 17, 2018
Publicly Available Date Nov 13, 2019
Journal Journal of Analytical Atomic Spectrometry
Print ISSN 0267-9477
Electronic ISSN 1364-5544
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 33
Issue 12
Pages 2184-2194
Keywords Analytical Chemistry; Spectroscopy
Public URL
Publisher URL!divAbstract
Additional Information : This document is Similarity Check deposited; : Supplementary Information; : E. Louise Ander (ORCID); : E. Louise Ander (ResearcherID); : Elizabeth H. Bailey (ORCID); : Elizabeth H. Bailey (ResearcherID); : Scott D. Young (ORCID); : Simon R. Chenery (ORCID); : Simon R. Chenery (ResearcherID); : Single-blind; : Received 29 August 2018; Accepted 5 November 2018; Accepted Manuscript published 12 November 2018; Advance Article published 15 November 2018; Version of Record published 28 November 2018


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