SBIR Phase I: A Real Time Analyzer for Chlorinated Hydrocarbons

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This Small Business Innovation Research Phase I program will test a novel method for detecting chlorinated hydrocarbons, and has particular application to monitoring soil, subsoil, and vadose zones. Chlorinated hydrocarbons comprise one of the most widespread, chemically long-lived classes of hazardous waste The compounds are denser than water and migrate downward through groundwater and vadose zones. It is often difficult to verify the effectiveness of subsurface remediation methods because remediation activities--such as soil washing and solvent extraction--may exacerbate the migration. Thus, improved methods are required to monitor concentrations of these compounds. Any new analysis technique must be field deployable, provide rapid (real time) response, and must be selective for chlorinated hydrocarbons in the presence of large backgrounds of inorganic chlorides. This will be a monitoring method that can provide continuous determination of changes in the local concentrations of the chlorinated solvents during remediation. The approach can be engineered for use with cone penetrometers or can be implemented in fixed locations including well headspace areas. Vapor including chlorinated organic compounds is sampled through a membrane used to exclude liquids, then is decomposed in an electric discharge. The concentration of discharge-produced HCI is measured by near-infrared diode laser spectroscopy. Fiber optics bring the laser light to the measurement region from a miniature diode laser that is kept above ground and that can be multiplexed among numerous measurement points. This approach guarantees rapid time response and low operating costs. Ppm detection limits for chlorinated hydrocarbons with a 1 second response time and a measurement dynamic range of 104 are anticipated. The proposed technology is designed to be compatible with cone penetrometry in order to take advantage of the market for remediation diagnostics that has already been created around the use of cone penetrometers. Chlorinated hydrocarbons account for 35 to 40% of contamination in soil and ground water at thousands of sites requiring remediation.