The determination of lead isotope ratios in environmental samples using a batch quality control protocol is described. Isotope ratios are computed with respect to 204Pb and are corrected for mass discrimination by the addition of thallium to all solutions. The batch quality control protocol entails measurements of two separate control samples, namely National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 981 Common Lead and a galena sample independently analysed by thermal ionization mass spectrometry. The present study demonstrates results of these two control samples for 43 sample batches analysed over a two-year period of time. Modified Youden-type plots of the two-sample sums and differences are constructed in order to estimate over-all accuracy for individual batches and collectively for the entire dataset. This statistical treatment indicated that 95% of the batches have estimated over-all relative uncertainties for the ratios 206Pb:204Pb, 207Pb:204Pb and 208Pb:204Pb of less than 1.23, 1.45 and 1.77%, respectively.
- Batch quality control
- Inductively coupled plasma mass spectrometry
- Lead isotope ratio determination
- Thallium-based mass discrimination correction
- Youden two-sample protocol
ASJC Scopus subject areas
- Analytical Chemistry