In the framework of the EURAMET (former EUROMET) Project 924, a comparison measurement was performed for national metrology institutes (NMIs) and expert laboratories (here called potential calibration laboratories, PCL) mostly from Europe. For the NMIs, the part of this project on nickel, cadmium and lead measurements was registered as the supplementary comparison EUROMET.QM-S2, while the part of the project on mercury was registered as the CCQM-P100.1/2 Pilot Study. This comparison was related with the implementation of the EU Water Framework Directive 2000/60/EC (WFD) and served as an opportunity for the participants to verify the performance of their measurement procedures for the heavy metals Hg, Ni, Cd and Pb in water at concentration levels close to the environmental quality standards (EQS). The EQS were defined in the WFD for hazardous chemical substances of priority.

The comparison consisted of two parts using the following samples: ultrapure water which was gravimetrically spiked with the elements mentioned above to a concentration level close to the EQS values, and natural water fortified with the elements to slightly higher concentrations than the EQS values. The measurement results confirmed the good measurement capabilities of the NMIs and expert laboratories as well, even for the most challenging measurement of mercury. The standard deviation of the mean of all results does not exceed 9%.

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 EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).