COMPOUND DETECTION AND CONCENTRATION ESTIMATION BY OPEN-PATH FOURIER-TRANSFORM INFRARED SPECTROMETRY AND CANISTERS UNDER CONTROLLED FIELD CONDITIONS

The University of Kansas-Lawrence and the U.S. EPA/Region VII conducted a study intended to assess the qualitative and quantitative capabilities of three FTIR systems. The instruments were arrayed along parallel, adjacent paths, which were 50 m downwind and perpendicular to the centerline of an artificially generated volatile organic compound (VOC) plume. Fifteen releases, consisting of mixtures of unknown compounds selected from a target list of 27, were made. Path-integrated VOC concentrations along the IR paths ranged from approximately 30 to 300 ppb. Identification of halogenated compounds was excellent, it was not as good, and differed from participant to participant, for unsubstituted compounds. Quantification of aliphatic halogenated compounds resulted in less than a 15% mean difference when compared with canister results. Statistical testing indicated that all three FTIR instruments produced concentrations that agreed fairly well with canister values, but also indicated some differences among the three instruments.