Conversion of Chlorinated Volatile Organic Compounds to Carbon Dioxide and Methyl Chloride for Isotopic Analysis of Carbon and Chlorine

Abstract

A nonaqueous, high-temperature method is described for converting micromole quantities of chlorinated volatile organic compounds to CO2 and CH3Cl for C and Cl isotope ratio determinations. This method provides an improved analytical approach for using C and Cl isotope ratios in studies of the biodegradation of chlorinated volatile organic compounds in the environment. Conversion of reagent CH3Cl to CO2 + CuCl and then conversion of the CuCl back to CH3Cl by the present method gives typical yields of 99 ± 1% for CO2 and 91 ± 1% for CH3Cl, both products of >99% purity. An offset of −0.23 ± 0.05‰ is observed between the 37Cl/35Cl ratios of product and initial CH3Cl. Precision of the isotopic ratio measurements is better than ± 0.1‰ for a variety of chlorinated volatile organic compounds.