Trichloroethylene Radicals: An EPR/SPIN Trapping Study

Abstract : Trichloroethylene (TCE) is an environmental contaminant found in the soil and groundwater on several active bases as well as bases scheduled for closure. TCE is a halocarbon and is believed to cause environmental and biological damage through production of free radicals. As part of the process to develop environmental and health effects criteria for base clean-up the initial radicals produced by TCE were studied by electron paramagnetic resonance spectroscopy (EPR). Radicals of TCE were formed by gamma-radiation in a 60Co gamma-ray source. TCE at 77 deg K was irradiated at a dose rate of 1 Gy/min receiving a total dose of 10 By. The TCE radicals were detected with and without the spin traps 5,5-dimethyl-1-pyrroline-1-oxide (DMPO), N-tert-butyl-alpha-phenyl nitrone (PBN) and 3,5-dibromo-4-nitrosobenzenesulphonate (DBNBS). The structure of the spin trapped TCE radical was Cl2C=CH. The spin trap of choice for the study of radicals by EPR in biological tissue is PBN. The efficiency of PEN to trap the TCE radical was 20.6%.