INTRODUCTION The conclusion of a study conducted by the Bureau of Mines during 1966 (1)* established the need for a reliable@ quantitative method of analyzing exhaust carbonyls. The 1966 study demonstrated that the 3-methy1-2-benzothiazolone hydrazone (MBTH) method of analysis has limited utility The reasons are: (a) The MBTH method provides only a collective measure of aldehyde components@ (b) The method is limited to aliphatic aldehydes only@ (c) The responses are not the same for all the aliphatic aldehydes. In 1967@ Bureau of Mines researchers initiated a study of the DNPH method (2-4) for exhaust carbonyl determination. The 1967 effort was expended primarily in development of procedures for gravimetric and chromatographic analysis of synthetic carbonyl mixtures by the DNPH method. However@ a small number of tests were made upon exhaust samples also. Data from these preliminary tests using exhaust showed that (a) results by the gravimetric and by the chromatographic variations of the DNPH method disagree significantly@ and (b) a large sample volume is necessary for exhaust analysis by the DNPH method. These findings raised questions regarding usefulness of the DNPH method and prompted the 1968 study@ The 1968 research objective was to develop a reliable DNPH procedure that would provide detailed compositional data on exhaust carbonyls and would be compatible with the sampling techniques that involve variable-dilution proportional samplers. To this end@ the chromatographic variation of the DNPH method was developed to minimize or circumvent errors associated with hydrazone losses and interferences. Following such development@ reliability of the resultant procedure was evaluated by comparing it with the gravimetric and colorimetric (5) variations of the DNPH method. The 1968 study was conducted in two phases. The first phase consisted of developing specific procedures for determining exhaust carbonyls by the GC-DNPH@ Col-DNPH@ and Gr-DNPH methods. The second phase consisted of a comparison program that involved parallel application of the three variations upon a number of exhaust samples@ Following is a discussion of experimental details and results from each phase. * Underlined numbers in parentheses refer to items in the list of references at the end of this report.
API 4050-1969 history
1969API 4050-1969 PROCEDURES FOR DETERMINING EXHAUST CARBONYLS AS 2@4-DINITROPHENYLHYDRAZONES