Improved Emissions Speciation Methodology for Phase II of the Auto/Oil Air Quality Improvement Research Program - Hydrocarbons and Oxygenates

Analytical procedures for the speciation of hydrocarbons and oxygenates (ethers, aldehydes, ketones and alcohols) in vehicle evaporative and tailpipe exhaust emissions have been improved for Phase II studies of the Auto/Oil Air Quality Improvement Research Program (AQIRP). One gas chromatograph (GC) was used for measurement of C₁-C₄ species and a second GC for C₄-C₁₂ species. Detection limits for this technique are 0.005 ppm C or 0.1 mg/mile exhaust emission level at a chromatographic signal-to-noise ratio of 3/1, a ten-fold improvement over the Phase I technique. The Phase I library was modified to include additional species for a total of 154 species. A 23-component gas standard was used to establish a calibration scale for automated computer identification of species. This method identifies 95±3% of the total hydrocarbon mass measured by GC for a typical exhaust sample. Solid adsorbent cartridges or impingers were used to collect aldehydes and ketones. The HPLC procedure for the analysis of thirteen aldehydes and ketones has been modified to reduce analysis time by 50% and to allow a one-point calibration. The GC method for the analysis of alcohols has been modified to permit the analysis of both methanol and ethanol using a single procedure. Finally, the performance of the new procedures during hase II of Auto/Oil AQIRP will be described.