Carbon monoxide proficiency testing scheme with metrological traceability

This paper details the activities carried out by the Chemical Metrology Department of LATU in the development of a national proficiency testing (PT) scheme aimed at assessing the competence of laboratories in air quality parameters analysis. In this PT scheme, environmental monitoring laboratories were required to determine the concentration of elements in quartz-grade microfiber filters and impinger solutions, as well as to determine the amount fraction of a carbon monoxide in nitrogen gas mixture, within the range of (800 to 1700) µmol/mol. The focus of the present paper is mainly devoted to the second phase of the test, which addresses the preparation of the gas cylinder distributed to each participant for measurement. A detailed description of this stage is provided, along with the evaluation of the results reported by participating laboratories. This test provided an effective tool for participating laboratories to assess their national technical competence, using their preferred analysis methods.