The aim of key comparison CCQM-K105 was to demonstrate the measurement capabilities of the participating institutes with respect to the conductivity of multi-component aqueous salt solutions. Practical salinity results are currently not traceable to metrological references consistent with the International System of Units (SI). Nevertheless, salinity is one of the most important input quantities for oceanographic models, whose measurement data must be accurate on very long timescales. Thus, in order to determine the practical salinity value, there is a strong interest on the part of oceanographic researchers in establishing the traceability to the SI of conductivity measurements. To this end, the conductivity of a standard seawater sample, provided by the support laboratory (PTB), was measured in a way that was traceable to the SI. The nominal conductivity values of the solution were 5.3 S m-1 at 25 °C and 4.3 S m-1 at 15 °C. Thirteen institutes taking part in the comparison had to measure the conductivity values of the sample at both temperatures. The median was chosen for both values as an estimator for the KCRV, evaluated on the basis of the Monte Carlo method. An institute requested to be excluded from the determination of the KCRV because of contact problems of its cell. At 25 °C the KCRV is 5.3024 S m-1 with an interval of confidence (at the 95.45% level of significance) from 5.3005 S m-1 to 5.3044 S m-1. At 15 °C the KCRV is 4.2892 S m-1 with an interval of confidence (at the 95.45% level of significance) from 4.2877 S m-1 to 4.2907 S m-1. For the 'how far the light shines' statement the CMCs can cover the range 1 S m-1 to 15 S m-1 for the values 5.3 S m-1 at 25 °C and 4.3 S m-1 at 15 °C. This comparison is a follow-up of the CCQM Pilot Study P111. Main text. To reach the main text of this paper, click on Final Report.The final report has been peer-reviewed and approved for publication by the CCQM.

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The aim of the key comparison CCQM-K92 was to demonstrate the capabilities of the participating NMIs to measure electrolytic conductivity of an unknown sample.Two samples with nominal electrolytic conductivity values of 0.05 S m−1 and 20 S m−1 have been prepared for comparison. For the first time a conductivity value larger than those given in the IUPAC document [1] was measured in a CCQM comparison. Thus no calibration standards with similar conductivity value were available. The comparison was an activity of the Electrochemical Working Group (EAWG) of the CCQM and was coordinated by SMU.In the comparison NMIs from fifteen countries took part. The higher conductivity (20 S m−1) was measured by ten participants. Good agreement of the results was observed for the majority of participants.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).