AbstractA diffusive sampler was developed to provide a passive in situ method for long‐term monitoring of volatile organic compounds (VOCs) in the ground water at hazardous waste sites and waste disposal facilities. The sampler was constructed of a sorbent tube that fits inside a specially designed sampling chamber equipped with a diffusional membrane that is not permeable to water but has a high permeability rate for organic vapors. VOCs in the ground water, having relatively high Henry's Law constants, enter the chamber by molecular diffusion and are collected by the sorbent. After a predetermined exposure period, the sorbent is easily retrieved for laboratory analyses by gas chromatography/mass spectrometry (GC/MS), or qualitative concentrations can be determined in the field directly using specific‐indicator detectors in place of the sorbent. The measurement approach was evaluated in the laboratory by exposing the device to a solution of 22.5 μg/1o‐xylene before testing at a field site where the ground water was contaminated by trichlorethylene (TCE). Results of the laboratory and field studies indicate the sampling approach is viable for monitoring relatively low concentrations of VOCs over a one‐day sampling period, as well as providing longer monitoring periods up to
展开▼
