CCQM-1 interlaboratory study, measurement of lead amount content in water by a primary method of measurement:: direct isotope dilution

The first interlaboratory study of the Consultative Committee for Amount of Substance (CCQM) focused on the determination of lead concentration in a synthetic water sample. In the framework of the CCQM activities, only leading metrology institutes participated in the study. The prescribed analytical method was double isotope dilution mass spectrometry (IDMS) as a primary method of measurement (PMM). At the Institute for Reference Materials and Measurements (IRMM) the material was additionally analysed by direct IDMS as a primary method of measurement using, completely independently, a certified spike reference material. The work described in this paper concerns direct IDMS. Conclusions are drawn on the use of IDMS as a PMM, on the comparison of the results with those of double IDMS, on the use of a certified spike reference material and on the calculation of uncertainty.