A novel technique for rapid extraction of volatile organohalogen compounds from low permeability media

A new method for rapid extraction of Volatile Organic Compounds (VOC) from low permeability, unconsolidated geologic media such as clayey soil has been developed and tested using trichloroethylene (TCE) as the model compound. The technique is based on a combination of sonication and mechanical agitation of the samples. The sample vials, mounted in a special holder attached to an orbital shaker, were immersed in an ultrasonic bath during extraction. The extracts were analyzed by gas chromatography with electron capture detection (GC-ECD). The method was validated using clay samples from a TCE-contaminated industrial site by comparing TCE recoveries to those obtained by the standard methanol extraction. In all cases, the recoveries obtained with the new method were the same or better than the recoveries obtained with the reference method. The extraction time was shortened from 5 days with the standard method to less than 2 h with the new method. The new technique makes it possible to analyze a large number of samples in a short time, without the need for sample preservation and prolonged storage. It has good potential for on-site analysis to facilitate decisions while field investigations are in progress.