Stable chlorine isotope analysis of chlorinated acetic acids

Abstract: Chlorinated acetic acids (CAAs) constitute a group of polar organic compounds that are ubiquitous in the environment. Their environmental occurrence has been extensively studied but their sources are still not well constrained. Isotopic characterization of compounds found in the environment can provide additional information and allow their source apportionment. Previous studies indicate, however, that CAAs of industrial and natural origin may not be distinguishable by stable carbon isotope analysis only. This thesis presents an analytical method for stable chlorine isotope analysis of CAAs using gas chromatography/quadruple mass spectrometry (GC/qMS), for which systems are found in most laboratories. The method was cross-calibrated with an offline reference method and allows the determination of chlorine isotope signatures of CAAs with sample amounts as small as 10 pmol with good precisions of <1 ‰. With this method CAAs can be isotopically characterized at environmental relevant concentrations, in contrast to conventional offline methods were large sample requirements limit the application. This new method enables multi-element stable isotope analysis of CAAs and may help to identify and quantify sources of CAAs to the environment.