Photochemical air pollution is known to be caused largely by automotive emissions such as hydrocarbons and oxygenated hydrocarbon derivatives. Unlike the hydrocarbons, the contribution of the oxygenates has been virtually unexplored, mainly because of lack of appropriate analytical methods. The objective of this study was to identify and estimate the levels of oxygenated hydrocarbon derivatives in exhaust from simple hydrocarbon fuels. This information is expected to yield ultimately estimates of the relative levels of various classes of oxygenates in exhaust from full-boiling-range gasolines. Identification and measurement of oxygenates in exhaust from the simplified fuels were accomplished using gas chromatography in conjunction with time-of-flight mass spectrometry. The analytical procedure involved concentration of the exhaust organics, followed by a two-stage chromatographic separation of the resultant mixture of oxygenates and hydrocarbons. Identified oxygenates in exhaust from nine test fuels included saturated and unsaturated aldehydes, ketones, and alcohols, as well as ethers, esters, and nitroalkanes; analytical data on organic acids were inconclusive. Of the identified noncarbonyl oxygenates, phenols, cyclic ethers and nitromethane appear to be relatively the most abundant.

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Procedures have been developed for routine analysis of automotive fuels and the unburned hydrocarbon of exhaust emissions. Specific attention is given to the hydrocarbon components that are photochemically reactive. Problems encountered in all phases of the analytical method are identified, and procedures that constitute a reasonable compromise between accuracy and practicality are defined. A packed and an open tubular column were used to separate the hydrocarbon content of exhaust and gasoline-vapor samples into 165 component groups; analysis time is 30 min. Raw chromatographic data are rapidly processed using a high-speed electronic integrator and a computer technique for automatic interpretation of chromatographic spectra.

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