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Recent changes in regulatory practices have brought about a need for speciated analysis of the volatile organic components of vehicle exhaust. The purpose of this study was to allow interested laboratories to participate in a Round Robin so that each could assess their speciation methodologies. “Synthetic exhaust” samples were prepared of mixed DNPH-carbonyl standards deposited on DNPH cartridges, and solutions of alcohol in water. The fifteen participating laboratories included automotive, contract, petroleum and regulatory organizations. The results described in this paper consider only variability associated with the analytical measurement of samples that have already been collected in impingers or on cartridges. In general, alcohols (methanol and ethanol) were quantified without difficulty. With the exception of acrolein and crotonaldehyde, the quantitation of the carbonyl samples was very good considering the variety of analytical methods that were used.

A Coordinating Research Council, Inc. (CRC) cooperative program was conducted to determine the difference in octane requirements between technical raters and “customers.” The trained raters used the CRC E-15 procedure to determine the octane requirement of the vehicles while the customers' perception and objection to knock were determined through the use of a questionnaire. The results showed that the customers' objections and perceptions were overwhelmingly based on knock, rather than acceleration performance or after-run. The difference between the technical and customer octane requirement at the midpoint satisfaction level was 3.8 (R+M)/2 octane numbers using the population comparison and 4.1 (R+M)/2 octane numbers using the distribution of delta analysis. The statistical analysis of the database also showed that the differences between customer objection and perception levels were generally small (less than or equal to 1 (R+M)/2 octane number).