Development of SI-Traceable Certification of Hydrogen Chloride Gas Standards

Cassie Goodman, NIST (US)

Recent changes to the United States of America (USA) Environmental Protection Agency (EPA) regulations, require that the continuous emission monitoring of hydrogen chloride (HCl) gas be traceable to gas standards certified by the National Institute of Standards and Technology (NIST).  These changes, which apply to emissions from both coal- and oil-fired electric power plants and cement-producing facilities, are intended to ensure that the average HCl emissions levels do not exceed approximately 1 mmol/mol.  As such, the new regulations are far reaching and require the routine certification of vendor gas amount-of-substance standards for HCl that are traceable to the International System of Units (SI).  In accordance with these regulations, NIST is developing new gas standards which will cover the range of 1 to 1000 µmol/mol of HCl in N2 balance gas with a relative expanded (k=2) uncertainty of less than 5 %.  The technical basis for the certification methodology will be presented including: primary certification of gaseous HCl concentration in terms of chloride anion Standard Reference Material (SRM) 3182 after aqueous trapping and analysis by ion chromatography; primary certification referenced to dynamic, gravimetric standards produced by a magnetic-suspension-balance/permeation-tube system with analysis using a commercial cavity ring-down spectroscopy system; secondary certification using Fourier transform infrared spectroscopy analysis.


Pen Profile

I received my B.S. in Chemistry in 2012 and an M.S. in Chemistry, with an emphasis in Synthetic Organic Chemistry, in 2014.  I joined the National Institute of Standards and Technology in 2014 as a Research Chemist in the gas sensing metrology group.  My principle areas of activity include:  conducting the US EPA Blind Audit; SRM / NTRM certification of low level NO and SO2; Development of new multi-component VOC standards; Development of the HCl RGM program.


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