Use of Symmetric Tetrachloroethane to Age Date Chlorinated Solvent Releases

Manufacturing impurities in chlorinated solvent products are of significant forensic importance for bracketing when a release occurred and/or identifying the source. While forensic techniques traditionally used for age dating and source discrimination, such as compound specific isotope analysis (CSIA), isotopic and chemical ratio analysis, reconstructed plume techniques, surrogate chemical indicators and stabilizers are available, less emphasis has been given to the use of manufacturing impurities as a corroborative technique. The use of manufacturing impurities in PCE (tetrachloroethylene) and TCE (trichloroethylene) produced via the oxychlorination of acetylene or ethylene offers a means to estimate when these chlorinated solvents were produced. Of the, the 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) is one of the various manufacturing impurities generated when producing TCE, PCE and methyl chloroform. TeCA provides the means to identify that the solvent was manufactured prior to about 1977. This chapter discusses the historical use, synthesis, physiochemical properties and applications of TeCA.