Quantitative ELISA of polychlorinated biphenyls in an oily soil matrix using supercritical fluid extraction

Soil samples from the GenCorp Lawrence Brownfields site were analyzed with a commercial semi-quantitative enzyme-linked immunosorbent assay (ELISA) using a methanol shake extraction. Many of the soil samples were extremely oily, with total petroleum hydrocarbon levels up to 240gkg-1, as determined by EPA Method 418.1. Commercial immunoassay results did not agree with confirmatory results obtained by gas chromatographic (GC) analysis of conventional Soxhlet extracts. Sample splits were subsequently extracted using both a methanol shake extraction and a methanolic Soxhlet extraction and analyzed by a quantitative PCB ELISA which has been previously described. The ELISA results for both types of extracts did not agree with GC confirmatory data except for the less oily samples. The current work reports re-analysis of these samples using supercritical fluid extraction (SFE) coupled to the same quantitative ELISA. Good agreement between GC results and SFE ELISA results was obtained.