A new synthetic zero air standard

Ruth Hill Pearce, NPL (GB)

Understanding the chemistry of the atmosphere and the mechanisms that control the levels of the gases involved in radiative forcing are of major global concern. There is a requirement for long-term observations based on accurate and stable standards of the highest impact greenhouse gases to ensure that the data meets the requirements of WMO compatability goals, environmental policy makers as well as academic and regulatory users. Standards for these components are required with challengingly low uncertainties to improve the quality assurance and control processes used for the global networks to better assess climate trends. The WMO compatibility goals are 100 nmol/mol for CO2 in the northern hemisphere, 2 nmol/mol for CH4 and CO. High purity zero gas is required for both the matrix gas in the preparation of reference standards and for baseline calibrations of instrumentation. Quantification of the amount fraction of the target components in the zero gas is a significant contributor to the uncertainty and is challenging due to limited availability of reference standards at the amount fraction of the measurand and limited analytical techniques with sufficient detection limits.  NPL has developed a new synthetic zero air standard with a matrix of N2, O2 and Ar, closely matching ambient composition and with an accurate quantification of the amount fraction of CO, CO2, and CH4 impurities.


Pen Profile

Ruth is currently researching environmental and industrial gas metrology at the National Physical Laboratory (NPL), and is primarily involved in investigating reference standards for greenhouse gases which provide traceability for global atmospheric air quality monitoring.
After receiving her PhD from Imperial College London she subsequently completed a Marie Curie placement at Linköping University in Sweden, returning to Linköping as a postdoctoral researcher then as an assistant professor developing gas sensors for environmental and industrial monitoring. Ruth first joined NPL’s Quantum Detection Group in 2012, moving to the Gas Metrology Group within the Environment department in 2015.

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