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Show MEASUREMENT OF AIR TOXICS IN ENGINE EXHAUST USING FOURIER TRANSFORM INFRARED (FTIR) SPECfROSCOPY Jeffrey P. laCosse, Larry D. Ogle, and Gunseli Sagun Shareef Radian Corporation P.O. Box 13000 Research Triangle Park, North Carolina 27709 James M. McCarthy and James M. Evans Gas Research Institute 8600 West Bryn Mawr Avenue Chicago, Illinois 60631 IN1RODUCI10N In response to the 1990 Clean Air Act Amendments, the Gas Research Institute (GRI) is investigating air toxics emissions from natural gas industry equipment. Included in this effort are measurements from internal combustion engines, one of the source categories targeted by the U.S. Environmental Protection Agency (EPA). The scheduled promulgation date for Maximum Achievable Control Technology (MACf) based standards for the engines category is the year 2000. Formaldehyde and other aldehydes are the potential air toxics species in engine exhaust. GRI's efforts are focused on collecting air toxics emissions data to advance the information base for engines. In addition, such data could facilitate industry's participation in EPA's Share-a-MACf program for development of MACf standards for the engines category. To ensure the quality of such data, there is a need to develop and use validated methods for measuring emissions of pollutants of concern. However, at inception of the program, there were no EPA-validated sampling and analytical methods available for measuring formaldehyde and other aldehydes potentially present in engine exhaust. Manual methods available for measuring aldehydes from combustion sources, such as SW-846 Method 0011 and California Air Resources Board (CARB) Method 430 were considered for use in the test program.1 ,2 Both manual methods are based on derivatization of 2,4-dinitrophenylhydrazine (DNPH) in impinger solutions. When applying the DNPH methods, inconsistent results were observed for engine exhaust measurements. Preliminary data indicated differences between measurements collected by extractive Fourier Transform Infrared (FflR) spectroscopy and the DNPH based measurements in some of the tests. In some cases, the DNPH solution used to recover the aldehydes was observed to be completely clear, indicating the DNPH solution, normally bright orange in color, was completely consumed even though less than a stoichiometric amount of aldehydes was present. Additionally, high variability was observed in CARB Method 430 triplicate measurements for some of the tes~ runs. Vairavamurthy, et aI., reported previously that ozone, nitrogen dioxide (N02) and sulfur dioxide (S02) are interferences with the DNPH-aldehyde reactions, though NOl did not appear to be an interferant in ambient air measurements.3 Recently, Karst, et al., reported N02 as a reactant with DNPH and a possible interferant to the quantitative 1 |