Development of a fifteen component hydrocarbon gas standard reference material at 5 nmol/mol in nitrogen

Abstract

Primary gravimetric gas cylinder standards containing fifteen alkane, alkene and aromatic hydrocarbons (C2–C10) were prepared. A procedure previously developed to prepare gas cylinder standards for volatile organic compounds at the 5 nmol/mol (ppb) level was used. The set of primary hydrocarbon gas standards prepared by this procedure were intercompared by using gas chromatography with a hydrogen flame ionization detector (GC-FID). The linear regression analysis showed excellent agreement among the standards for each compound. Similar mixtures containing many of these hydrocarbons have been evaluated over time and have shown stability of the concentrations in aluminum gas cylinders for three years. This research resulted in the production and certification of Standard Reference Material (SRM) 1800, which contains fifteen hydrocarbons in nitrogen at a nominal concentration of 5 nmol/mol for each analyte. A batch of twenty-four cylinders containing the mixture was prepared at NIST following previously demonstrated protocols for their preparation. Each cylinder was analyzed against one cylinder from the batch, designated as the “lot control”, for each of the fifteen hydrocarbons. The data showed that the batch was homogeneous, from 0.2 to 0.7% depending on the compound, and stable for each hydrocarbon in the mixture resulting in certification and issuance of SRM 1800.