Collaborative Study of Soils Spiked with Volatile Organic Compounds,

Vapor fortification is a method of spiking soils with volatile organic compounds VOCs that was recently developed for producing materials suitable for performance evaluation and quality assurancequality control QAQC. Using this treatment method, soil subsamples enclosed in heat-sealed glass ampoules were distributed to 16 laboratories for a collaborative round-robin study. The sample sets consisted of duplicates of three different soils. Each soil subsample had been vapor-fortified with the following VOCs trans-1,2-dichloroethylene TDCE, trichloroethylene TCE, benzene Ben and toluene Tol. The laboratories were requested to report analyte concentration estimates for these four analytes and any other detected organic compounds after performing a methanol extraction, purge-and-trap gas chromatography, mass spectrometry analysis. The results from the 12 laboratories that met all of the design criteria produced a range of relative standard deviations from 8.5 to 28.2, with a pooled standard deviation of less than 13. The smallest range of consensus values was for Ben pooled RSD 9.0, while the determination of TDCE showed the greatest overall uncertainty pooled RSD 20.3. This round-robin effort confirmed that the use of vapor-fortified soils sealed in glass ampoules is a precise way of preparing and storing VOC-spiked soil subsamples. AN