Modular methodology for determination of polychlorinated biphenyls in soil as Aroclors and individual congeners

A comprehensive screening and confirmatory method was developed for monitoring polychlorinated biphenyls (PCBs), both as Aroclors and as individual congeners. This approach incorporates extraction, extract cleanup, and analysis modules designed to match cost, time, and data quality requirements. Soxhlet, sonication, supercritical fluid, and accelerated solvent extractions were evaluated. Carbon chromatographic cleanup procedures were used for separation of congeners on the basis of ortho substitutions, which permitted calculation of toxicity equivalents. Individual congener determinations, congener total histograms, and peak comparison techniques for Aroclor identification were elaborated by using high and low resolution mass spectrometric data. A screening procedure based on immunoassay using the Ohmicron PCB RaPID Assay kit gave results comparable to those obtained by gas chromatography with electron capture detection in the range 0.40-230 ppm, when the appropriate Aroclor calibrator was used.