The Challenge of Developing Primary Standards Mixtures of Carbon Dioxide at Atmospheric Levels

Abstract

In recent years, the need for the quality control, reliability, and traceability of analytical results has been strongly emphasized. The National Metrology Institute – Inmetro is involved in improving measurement capabilities to provide confidence level regarding greenhouse gases standards. The chapter describes the development of certified reference materials of carbon dioxide in atmospheric synthetic air that are used to monitor its concentration in the atmosphere. Considering the contributions from gravimetry preparation and its verification analysis by cavity ringdown spectroscopy (CRDS), the relative expanded uncertainty of the standard mixture of carbon dioxide was lower than 0.5% for the range studied from 370 to 550 μmol/mol, which is comparable to the average of 0.25% relative uncertainties presented on international standards mixtures.