Evaluation of GC/MS Method for the Determination of Indoor Air Pollutants by Adsorption/Liquid Extraction: Cooperative Test for the Analysis of Toxic Air Pollutants (Part 7)

A gas chromatography/mass spectrometry (GC/MS) method by an adsorption/liquid extraction has been developed for the determination of organic pollutants in indoor air. Round robin tests using this method for eight organic pollutants such as toluene, ethylbenzene, o-and p-xylene, styrene, p-dichlorobenzene, trichloroethylene and tetrachloroethylene were conducted by 15 laboratories. Three kinds of test samples were analyzed by each laboratory: a) an adsorbent of activated charcoal (sample A) on which gaseous sample of the pollutants was collected, b) an adsorbent of activated charcoal (sample B) to which methanol solution of the pollutants was directly added, c) carbon disulfide solution (sample C) of the pollutants. The pollutants were extracted from the adsorbents by carbon disulfide and then determined by gas chromatography/mass spectrometry (GC/MS) after addition of toluene-d8 as an internal standard. The observed values of the pollutants except for those of styrene and p-dichlorobenzene after rejection tests were coincident with the calculated values. The recoveries of styrene and p-dichlorobenzene from the adsorbent of charcoal, that is, the ratios of the observed values to the calculated ones were 0.34-0.57 and 0.51-0.66, respectively. The intra-laboratory relative standard deviations (RSD) of the ratios for all samples were 0.74-12%. The interlaboratory RSDs of the ratios for sample A were 49% for styrene, 33% for p-dichlorobenzene, and 8.512% for the others. The RDSs for sample B were 33% for styrene, 22% for p-dichlorobenzene, and 14-19% for the others. The RDSs of sample C were in the range of 2.8-8.0% for all pollutants. These results indicated that the six pollutants in indoor air except for styrene and p-dichlorobenzene could be determined precisely by using this method. It should be necessary to develop the alternative calibration method and/or improve the recovery of those two pollutants from the adsorbent of charcoal for precise and simultaneous determination of all the pollutants.