Determination of Chlordane in Soil by LC/GC/ECD and LC/GC/EC NIMS with Comparison of ASE, SFE, and SOXHLET Extraction

Abstract

Chlordane is a polychlorinated mixture that was used as a long-lived pesticide and now is considered a potential endocrine-disrupting compound. The Environmental Sciences Division is involved in modernizing methods for a number of analytes that are potential target substances for dietary studies, endocrine disrupter studies, Superfund site monitoring, and human exposure studies. In this work, chlordane is determined in soils using each of three different liquid phase/supercritical fluid (CO₂) extractions followed by a two-dimensional chromatographic separation based on high performance gel permeation chromatography (HPGPC) followed by GC/electron capture detection (GC/ECD) and GC/electron capture negative ion mass spectrometry (GC/EC NIMS). Liquid phase extractions were carried out using accelerated solvent extraction, supercritical fluid extraction, and Soxhlet extraction. The preparative liquid chromatographic part of the work is used in an off-line fractionation mode of HPGPC. Further cleanup is afforded by solid-phase extraction using silica cartridges. Soils spiked at 2 ppm, 0.2 ppm, and 0.02 ppm were quantitated using GC/ECD and GC/EC NIMS with recoveries usually greater than 80%. Soil from a Superfund site and a standard reference material sediment were analyzed as examples of real samples. The modernized methodology developed in this work should offer improved approaches for Superfund analyses and for monitoring methods used in determining potential exposure to endocrine-disrupting compounds while minimizing solvent usage compared to previous methodology.