Dichloromyristic Acid, a Major Component of Organochlorine Load in Lobster Digestive Gland

Abstract

It is well established that PCBs and chlorinated pesticides account for only some 15% of extractable organically-bound chlorine (EOCl) in samples from marine and non-marine environments. Work by other investigators on marine sediments and lipids from highly contaminated fish, collected near kraft pulp mills, has shown that chlorinated alkanoic acids contribute significantly to the EOCl. The present investigation extends this work to lipids from lobsters (Homarus americanus) captured in an industrial harbor well removed from any pulp mill effluent. The relatively low chlorine content of these lipids (30−100 μg g-1) necessitated development of fractionation and analysis procedures more discriminating and sensitive than those used previously. Neutron activation analysis for total chlorine was used to monitor the extraction, cleanup, transesterification, and selective EOCl enrichment of the lipids. Fractionation on a Sephadex LH-20 column then concentrated the EOCl into fractions separated from the bulk of the lipid. Mass spectrometric detection using dis sociative electron capture, monitoring only chloride ions, identified those GC peaks containing chlorine. Conventional negative ion mass spectrometry provided mass spectra for peaks of interest and enabled identification of a dichloromyristic acid as a lipid component accounting for ca. 20% of the EOCl on a semi-quantitative basis.