Trace Organic Analysis of Suspended Sediments Collected with an In-Stream Composite Sampler: The Need for a Standard Method

Abstract

Sorption to suspended materials is an important mechanism controlling the transport and fate of nonpolar trace organic chemicals in aquatic environments. To simultaneously examine the aqueous and suspended phases, an in-stream filtration sampler has been developed for composite sampling of suspended materials with subsequent extraction of the filtered aqueous phase by XAD resins. The in-stream filtration sampler and broad spectrum analysis were used to evaluate the fate of nonpolar trace organics in a New Jersey river/reservoir/treatment plant system. GC and GC/MS analyses revealed a very differnt spectrum of compounds in the aqueous and associated suspended material phases. In the suspended material extracts, GC/MS tentatively identified alkyl phenols, pulp mill type wastes (long-chain fatty acids, juvabiones, and abietic acid derivatives), and plasticizers. GC/MS analysis of ether extracts of XAD resin tentatively identified petroleum related PAHs, straight and branched chain aliphatics, and phthalates. Only toluene was found in both the aqueous and suspended material phases. These data indicate that the suspended material phase and the dissolved phase are not in equilibrium in this particular watershed. An acetone/hexane solvent system was used to soxhlet extract the trace organics that were present on collected suspended materials. Artifacts, primarily condensation products of acetone, were produced during the filter cleaning and the soxhlet extraction processes. The artifacts produced were carefully evaluated and quality assurance procedures assured that they did not interfere with the analysis. The development of an appropriate quality assured extraction method which minimizes artifact formation is needed for the broad spectrum analysis of nonpolar trace organics associated with suspended materials.