Application of Purge-and-Trap Method to Fast and Convenient Field Analysis of Water and Soil Samples

Conventional purge-and-trap methods require a laboratory gas chromatography—mass spectrometry system. In this study we have demonstrated that the purge-and-trap method can be applied to fast field analysis for volatile organic compounds in water and soil samples. The analytical system employed in this study consisting of a portable sample concentrator and a fast microchip gas chromatograph with a miniaturized thermal conductivity detector, appears to be suitable for this purpose. Experiments on seven volatile organic compounds have shown linear instrument responses in the ranges of 10–1,000 μg/L for water samples and 40–4,000 μg/kg for soil samples, demonstrating the applicability of this method. The detection limits are estimated to be in the ranges of 0.5–10 μg/L for water samples and 3–50 μg/kg for soil samples, which are considered fairly good for field work. The estimated absolute recoveries and method recoveries are discussed in the paper. The drop in recovery for heavier volatiles appears to be caused primarily by the disproportionately lower trap efficiency.