Key Comparison CCQM-K36.2016 was a follow-up comparison for K36 and provided updated support for the corresponding calibration and measurement capability (CMC) entries in the BIPM CMC database. It aimed to demonstrate the capabilities of the participating NMIs to measure electrolytic conductivity of aqueous electrolyte solutions in the conductivity range 0.15 S m−1 to 1.5 S m−1 and in the conductivity range 1.5 mS m−1 to 15 mS m−1. To this end electrolytic conductivity of a potassium chloride solution (nominal conductivity 0.5 S m−1) and of a HCl solution (nominal conductivity 5 mS m−1) had to be measured. 17 NMIs participated in the comparison. The key comparison reference value (KCRV) of the KCl solution was (0.50999 +/-0.00032) S m−1 and the KCRV of the HCl solution was (4.9877 +/-0.012) mS m−1. Both values were estimated from the medians of the results considered eligible for KCRV calculation. They were given with their expanded uncertainties (95% coverage). The majority of the 0.5 S m-1 results were consistent with the KCRV. Two institutes showed a small inconsistency, one outlier was observed. The conductivity of the HCl solution showed a small, but steady linear drift of 0.00006843 mS m−1 per day during the measurement period and was corrected for KCRV calculation. Some institutes reported unstable measurement conditions for this solution. The results of seven participants have been inconsistent with the KCRV. 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 (CIPM MRA).

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The key comparison CCQM-K96 was organized jointly by the inorganic and electrochemistry working groups of CCQM to test the abilities of the metrology institutes to measure the amount content of dichromate. Slovak Institute of Metrology with help of KRISS acted as the coordinating laboratories. Eight NMIs took part in the comparison. All participants used high accuracy constant current coulometry. Good agreement of the results was observed.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 (CIPM MRA).

This key comparison (KC), CCQM-K73, was performed to demonstrate the capability of the participating National Metrology Institutes (NMIs) to measure the amount content of H+, νH+, in an HCl solution with a nominal νH+ of 0.1 mol kg−1. The comparison was a joint activity of the Electrochemical Working Group (EAWG) and Inorganic Analysis Working Group (IAWG) of the CCQM and was coordinated by NIST (USA) and CENAM (Mexico).The agreement of the results was not commensurate with the claimed uncertainties of the subset of participants that claimed small uncertainties for this determination. A workshop on technical issues relating to the CCQM-K73 measurements was conducted at the joint IAWG-EAWG meeting at the Bureau International des Poids et Mesures (BIPM), Paris (Sèvres) in April 2010. Several possible sources of bias were investigated, but none could explain the observed dispersion among the participants' results.In the absence of a specific cause for the dispersion, the IAWG and EAWG decided to assign a Key Comparison Reference Value, KCRV, and standard uncertainty of the KCRV, uKCRV, based on the DerSimonian–Laird statistical estimator. The uKCRV is dominated by the between-laboratory scatter of results in CCQM-K73. The uncertainty estimates from the participants with the lowest reported uncertainties remain unsupported by this KC.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 (CIPM MRA).

Main text The CCQM key comparison K73.2018 is a follow-up comparison of CCQM-K73. It was performed to demonstrate the capability of the participating institutes to measure the amount content of H+ in hydrochloric acid of 0.1 mol·kg−1 molality. 16 NMIs participated in this comparison. The comparison was coordinated by PTB. The sample showed a slight but significant instability by loss of water of around 0.11 μmol kg−1d−1 corresponding to 0.02 % over the measurement period. Therefore, the results were corrected for this instability. The results of this key comparison show good equivalence between the majority of participants. The equivalence is significantly better compared to the first comparison CCQM-K73. 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 (CIPM MRA).