Stable chlorine and carbon isotope measurements of selected chlorinated organic solvents

Stable Cl and C isotope ratio results for 3 selected chlorinated solvents, perchloroethylene (PCE), trichloroethylene (TCE) and 1,1,1-trichloroethane (TCA) provided by 4 different manufacturers are presented. The isotope ratio for all compounds range between -3.5 and + 6.0 parts per thousand for delta(37)Cl and from -37.2 to -23.3 parts per thousand for delta(13)C. The greatest Cl-37 difference between manufacturers is observed in the TCE samples which show delta(37)Cl values of -2.5 parts per thousand for PPG, + 2.4 parts per thousand for ICI and + 4.4 parts per thousand for DOW. TCAs show a smaller range (-2.4 to +2.0 parts per thousand), while the TCEs have slightly different Cl-37 contents. The C-13 data show the most distinct delta(13)C values for PCEs (-23.3 for DOW, -24.1 for Vulcan, - 33.8 for PPG and - 37.2 parts per thousand for ICI) while both TCEs and TCAs show a smaller delta(13)C range, but still distinct differences. These preliminary data suggest that each manufacturer and solvent type may have distinctive delta(37)Cl and delta(13)C values. These results show that by using a combination of Cl-37 and C-13, there is a potential to indicate a specific source of chlorinated solvents, as well as an ability to delineate contamination episodes caused by these compounds in groundwaters.