Abstract. A key comparison (CCQM-K49) of the determination of toxic and essential elements in bovine liver has been conducted under the auspices of the CCQM Inorganic Analysis Working Group (IAWG). All elements were present at naturally occurring levels, and in naturally occurring (non-spiked) forms in this material. Sixteen national metrology institutes (NMIs) submitted data for this study using a variety of analytical methods.

Measurands for this study consisted of elements that were expected to be relatively easy to determine (Fe and Zn), moderately difficult to determine (Se, Cd and Pb), and very difficult to determine (Cr and As). The results of this comparison seem to bear these rankings out, with the possible exception that Se was more difficult to determine than Cd and Pb, perhaps due to the difference in the amount of experience for many NMIs with this element compared to Cd and Pb. However, Se seemed to be less difficult to determine than Cr and As based on the dispersion of the reported data and the typical expanded uncertainties reported by the NMIs.

Results for this key comparison are highly encouraging in that all reported values, with only three exceptions, agreed within stated (expanded) uncertainties with the key comparison reference values (KCRVs), or were within an additional 1% of the KCRV. Since this key comparison included 60 separate determinations of the studied constituents, 95% of the results could be considered successful.

Main text. 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 kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).