Testing and optimization of a mobile Fourier transform infrared (FT-IR) spectrometer system for the monitoring of volatile organic compounds (VOCs).

摘要

The development of a mobile longpath Fourier transform infrared (FT-IR) spectrometer system for the analysis of volatile organic compounds (VOCs) in the atmosphere began at Kansas State University over 5 years ago. Since its initial development, the system has been extensively tested in the field. The stages of testing were outlined by the United States Environmental Protection Agency (US EPA) Region VII office in Kansas City, Kansas.; Testing of the mobile longpath FT-IR system was divided into 3 stages. The first stage of testing involved controlled releases of VOCs at the University of Kansas, in collaboration with the Department of Civil Engineering. The second stage of testing involved the monitoring of uncontrolled releases of VOCs, but the site itself had been precharacterized by the US EPA using other atmospheric monitoring techniques. The second stage of testing began in the spring of 1990. The third and final stage of testing involved sampling of sites which had uncontrolled releases of VOCs and the site itself had no precharacterization work performed prior to sampling with the mobile longpath FT-IR system. Stage three testing began in the fall of 1990.; The sites sampled to date have included landfills, industrial facilities, US EPA Superfund sites, and waste water treatment facilities. All of the sites sampled have either been stage two or stage three type sites. Each of the sites sampled has presented its own set of problems and challenges and the sampling of these sites has allowed the longpath FT-IR system to be optimized for ideal performance in the field. Both the stage two and three sites have provided a large amount of experience in performing longpath FT-IR measurements for VOCs.; The longpath FT-IR spectrometer system has been shown to be a viable technique in the monitoring of VOCs. The longpath FT-IR system has sampled pathlengths from 50 meters to as large as 1 kilometer. The detection limits for chlorinated and fluorinated type compounds are in the 5-10 parts per billion (ppb) range while compounds such as aromatic hydrocarbons have detection limits in the 20-30 ppb range. The low detection limits and the ability of the longpath FT-IR system to provide real time qualitative and near real time quantitative results makes it a valuable technique for the monitoring of VOCs.