Abstract

Main text Twenty National Metrology Institutes and Designated Institutes registered in the CCQM Key Comparison of CCQM-K155 "Elements and Tributyltin in Seawater" and nineteen institutes submitted their results. Participants were requested to evaluate the mass fractions, expressed in ng/g, of arsenic, cadmium, copper, lead, nickel, zinc and ng/kg level of tributyltin in seawater. Key Comparison Reference Values (KCRVs) are assigned to the various measurands by the NIST decision tree approach (NDT). Participants used analytical methods of their choice. Most participants employed dilution or co-precipitation for sample treatment and analyzed the samples using Isotope Dilution Mass Spectrometry (IDMS) or standard addition method with ICP-MS, applying various interference removing techniques for different elements. For tributyltin, most participants utilized derivatization followed by liquid-liquid extraction, with analysis conducted using isotope dilution GC-ICP-MS. Successful participation in CCQM-K155 demonstrates measurement capabilities for determining mass fraction of transition elements (excluding mercury) and metalloids/semi-metals, with mass fractions ranging from 0.1 ng/g to 50 ng/g. Additionally, it covers small organo-tin and organo-mercury compounds with mass fractions from 1 ng/kg to 50 ng/g in a high-salt content matrix (seawater). To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).