Consultative Committee for Amount of Substance: metrology in chemistry (CCQM): REPORT FROM THE CCQM AD-HOC WORKING GROUP ON THE KCRV

摘要

Dr Cox, chair of the Key Comparison Reference Value Working Group (KCRVWG), outlined the terms of reference of his group (established by the President in April 2007), i.e., to examine the various approaches currently in use for the determination of the KCRV and its uncertainty, and to produce a set of guidelines that would be adopted by the CCQM for the calculation of these values. Once established, it would become feasible to link CMCs with results of KCs in a more transparent manner. Dr Cox briefly outlined earlier activities relating to document CCQM/09-03 wherein a set of thirteen data evaluation principles had been established, as well as document CCQM/09-15 containing criteria by which a CMC uncertainty can be judged in terms of a particular KC result (limited to conditions under which a 1:1 correspondence between the matrix, the measurand and its amount fraction and the measurement procedure applied were clearly established). Recent activities arising from the workshop in Rio de Janeiro in November 2009 focused on a half-day workshop, which was primarily a tutorial, and discussion of two further documents. The first of these, CCQM/10-03, provides guidance for KCRV and DoE calculations and a procedure for calculation of the KCRV through implementation of the earlier data evaluation principles. This is ongoing and comments have been solicited. The second, a procedures document complements the guidance document and contains worked examples of KC data evaluation which will be made available after further consultations and after the guidance document has been stabilized through additional discussions in the stakeholder community.