Determination of polychlorinated biphenyls in soil and sediment by selective pressurized liquid extraction with immunochemical detection

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A selective pressurized liquid extraction (SPLE) method was developed for a streamlined sample preparation/cleanup to determine Aroclors and coplanar polychlorinated biphenyls (PCBs) in soil and sediment. The SPLE was coupled with an enzyme-linked immunosorbent assay (ELISA) for an effective analytical approach for environmental monitoring. Sediment or soil samples were extracted with alumina, 10% AgNO3 in silica, and sulfuric acid impregnated silica with dichloromethane at 100°C and 2000psi. The SPLE offered simultaneous extraction and cleanup of the PCBs and Aroclors, eliminating the need for a post-extraction cleanup prior to ELISA. Two different ELISA methods: (1) an Aroclor ELISA and (2) a coplanar PCB ELISA were evaluated. The Aroclor ELISA utilized a polyclonal antibody (Ab) with Aroclor 1254 as the calibrant and the coplanar PCB ELISA kit used a rabbit coplanar PCB Ab with PCB-126 as the calibrant. Recoveries of Aroclor 1254 in two reference soil samples were 92±2% and 106±5% by off-line coupling of SPLE with ELISA. The average recovery of Aroclor 1254 in spiked soil and sediment samples was 92±17%. Quantitative recoveries of coplanar PCBs (107–117%) in spiked samples were obtained with the combined SPLE–ELISA. The estimated method detection limit was 10ngg−1for Aroclor 1254 and 125pgg−1 for PCB-126. Estimated sample throughput for the SPLE–ELISA was about twice that of the stepwise extraction/cleanup needed for gas chromatography (GC) or GC/mass spectrometry (MS) detection. ELISA-derived uncorrected and corrected Aroclor 1254 levels correlated well (r=0.9973 and 0.9996) with the total Aroclor concentrations as measured by GC for samples from five different contaminated sites. ELISA-derived PCB-126 concentrations were higher than the sums of the 12 coplanar PCBs generated by GC/MS with a positive correlation (r=0.9441). Results indicate that the SPLE–ELISA approach can be used for quantitative or qualitative analysis of PCBs in soil and sediments. To our knowledge, this is the first report of an SPLE–ELISA approach not requiring a post-extraction cleanup step for detecting Aroclors and coplanar PCBs in soil and sediment.