A Gas Chromatographic Method for Direct Analysis of Photochemically Nonreactive Hydrocarbons

Abstract

Ambient air quality criteria have been established for oxidants. The oxidants result from sunlight-initiated, chemical reactions in the atmosphere which involve hydrocarbons and oxides of nitrogen. All hydrocarbons, however, do not participate in these atmospheric reactions to the same degree. Methane, ethane, propane, acetylene, and benzene do not participate significantly. In efforts to assess the potential significance of various hydrocarbon sources, a means to analyze, directly, for the nonreactive hydrocarbons in the presence of a wide variety of other hydrocarbon and nonhydrocarbon compounds would be very useful. The total mass of reactive hydrocarbon emissions could then be determined by difference in conjunction with total hydrocarbon mass. A gas chromatographic system is described permitting direct determination of the nonreactive hydrocarbons. The system employs four packed columns, two utilized for C₁, C₂, and C₃ resolution and two for benzene resolution. A valve programmer is described permitting manual or automatic sequencing of these columns to a single flame ionization detector. Mention of specific manufacturers and models is illustrative and does not imply endorsement by the Environmental Protection Agency.