Stability study and uncertainty evaluation of CO2 certified reference materials for greenhouse gases monitoring

The continuous rising in the concentration of carbon dioxide (CO2) in the atmosphere is one of the main causes of the increase in the greenhouse effect and global warming. To monitor the alarming scenario and to provide Governments and decision makers with reliable emission data, gaseous certified reference materials (CRMs) at atmospheric CO2 amount fraction are needed. This paper describes two independent metrological traceability paths established at INRiM for the preparation of this kind of CRMs. The aim of this publication is to show a method for evaluating the uncertainty associated with CRM stability and to demonstrate that there is no significant trend in the results over time. Such CRMs are produced as an intermediate step towards the development of novel generation CRMs certified also for the isotopic composition.