CCQM Activities in the Gas Analysis Working Group

The technical approaches used for the GAWG Key Comparisons are the same as those used for the CMCs. In this way, the CMCs can be benchmarked through the CCQM studies. The GAWG has decided to conduct two types of Key Comparisons: 1) the Core Key Comparisons and 2) Analytical Challenge Key Comparisons. The Core Key Comparisons will test an NMI's core capabilities to produce gas standards, and each NMI will be required to participate in these exercises periodically. An example of a current active Core Key Comparison is 1000 µmol/mol propane of which NIST is a participant. These comparisons will be very broad in scope and cover a large number of non-reactive gas CMCs. The Analytical Challenge Key Comparisons will cover a very narrow scope, usually only the compound being compared. An example of these comparisons is the recent ammonia key comparison which covers only ammonia in the concentration range of 10 µmol/mol to percent levels.