Fiber optic raman probe detection of chlorinated hydrocarbons in standard soils

Chlorinated hydrocarbons such as trichloroethylene and methylene chloride are common contaminants in soils at polluted sites. The chemical characterization of contaminated soils as a precursor to remediation is important. Raman spectroscopy is especially useful for the selective determination of a broad range of compounds. A fiber-optic Raman probe suitable for use in a soil environment has been constructed and tested. The intensity of the Raman signal of the chlorinated hydrocarbons trichloroethylene and methylene chloride has been measured in a variety of standard and nonstandard soil and sand samples. The effect of the soil parameters (opacity, particle size, etc.) on the intensity of the Raman signal has been investigated. The general implications for spectroscopic fiber optic chemical sensors used in a cone penetrometer system are discussed.