Metrological traceability in gas analysis at I.N.Ri.M: gravimetric primary gas mixtures

Metrologically traceable measurements are needed, in environmental monitoring, to provide meaningful information on the pollution level and the possibility to have suitable reference standards is crucial to this purpose to calibrate instruments. The Italian National Institute of Metrological Research (I.N.Ri.M.), as a primary metrological institute, realizes and maintains primary standards for the basic and derived units of the International System of Units (SI). In this framework and regarding gas analysis, in the last few years I.N.Ri.M. has started a research line on the preparation of primary reference mixtures (PRMs) by the gravimetric method that led to plan and build a facility for evacuating and filling cylinders and a device for high precision weighing. In the present work the developments in such field at I.N.Ri.M. are reported to underline the relevance, in the atmospheric pollutants monitoring, of performing accurate and reliable measurements and having reference standards fit for the calibration of the analytical instrumentation.