Validation of a Test Method for Collection and Analysis of Chloroform Emissions From Stationary Sources

A test method based upon the adsorption of chloroform onto charcoal was evaluated for the collection and analysis of chloroform emissions from stationary sources. In this method, a source gas sample is pulled through adsorption tubes containing activated charcoal (to adsorb the chloroform), and chloroform is extracted from the charcoal with a hexane/methanol mixture. The extract is analyzed by gas chromatography with an electron capture detector. Procedures in Environmental Protection Agency (EPA) Method 301 were utilized to test the suitability of the method under field conditions at two sampling sites (paper mills). EPA Method 301 requires that four separate trains ("quad train") operate simultaneously in each run. During each run, two of the four sampling trains were spiked with a known amount of gaseous chloroform. The quad train sampling was performed six or more times. In the first field test, the stack emissions of chloroform were approximately 300 ppm, the mean spike recovery was 82%, the precision of the method for unspiked samples was within 5%, and the sampling bias was -43 ppm. Modifications were made to the sampling method and the spike gas introduction system. The revised method was then tested at a second field site which had chloroform emissions of approximately 220 ppm. The mean spike recovery improved to 95%, the unspiked sample precision was within 5%, and the sampling bias improved to -8.5 ppm.