DICHLOROMYRISTIC ACID, A MAJOR COMPONENT OF ORGANOCHLORINE LOAD IN LOBSTER DIGESTIVE GLAND

It is well established that PCBs and chlorinated pesticides account fa r only some 15% of extractable organically-bound chlorine (EOCI) in sa mples from marine and non-marine environments. Work by other investiga tors an marine sediments and lipids from highly contaminated fish, col lected near kraft pulp mills, has shown that chlorinated alkanoic acid s contribute significantly to the EOCI. The present investigation exte nds this work to lipids from lobsters (Homarus americanus) captured in an industrial harbor well removed from any pulp mill effluent. The re latively tow chlorine content of these lipids (30-100 mu g g(-1)) nece ssitated development of fractionation and analysis procedures more dis criminating and sensitive than those used previously. Neutron activati on analysis for total chlorine was used to monitor the extraction, cle anup, transesterification, and selective EOCI enrichment of the lipids . Fractionation on a Sephadex LH-20 column then concentrated the EOCI into fractions separated from the bulk of the lipid. Mass spectrometri c detection using dissociative electron capture, monitoring only chlor ide ions, identified those GC peaks containing chlorine. Conventional negative ion mass spectrometry provided mass spectra for peaks of inte rest and enabled identification of a dichloromyristic acid as a lipid component accounting for ca. 20% of the EOCI on a semi-quantitative ba sis.