Electronic Nose–Membrane Interface Probe for Geoenvironmental Site Characterization

This paper describes pioneering research to integrate a novel "electronic nose" (EN) technology with a membrane interface probe (MIP) for rapidly screening hydrocarbon contaminated sites. The electronic nose is an automated odor recognition device that detects and identifies chemical vapors based on the principles of human olfaction. The MIP is an in situ tool that samples volatile organic compounds from the subsurface and transports the vapor through tubing to analytical devices located on the surface. The electronic nose developed for this research was first trained and tested to identify vapor samples of benzene, toluene, ethyl benzene, and xylene at three different concentration levels. The integrated EN–MIP system was then tested in gasoline-spiked aqueous soil samples in the laboratory. In situ demonstration tests were conducted in collaboration with the U.S. EPA at a gasoline-contaminated site in Rhode Island. The EN–MIP system was successful in detecting and estimating the concentration levels of gasoline contamination at various depths.