Development and application of a novel method for high-throughput determination of PCDD/Fs and PCBs in sediments

A selective pressurized liquid extraction technique was developed for the simultaneous extraction of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) from contaminated sediments. The final method incorporated cleanup adsorbents (Florisil, alumina, and silica) into the extraction cell in a 1:1 ratio of matrix to individual adsorbent (w/w). Sulfur, a common interference found in sediments, was successfully removed by placing activated copper in the extraction bottle prior to extraction. No additional postextraction cleanup was required, and sample throughput was reduced to 2.5 h per sample. Target analytes were quantified using high-resolution gas chromatography/electron-capture negative ionization mass spectrometry and verified by high-resolution gas chromatography/high-resolution mass spectrometry. Though mean analyte recoveries (n = 3) of PCDD/Fs and dl-PCBs were 84 ± 5.8% and 70 ± 8.4%, respectively, mean surrogate recoveries for all PCDD/Fs using this novel method were greatly improved compared with US Environmental Protection Agency (USEPA) method 1613 (∼25-155%) and USEPA method 8290a (40-135%). After development, the method was used to examine surficial sediment samples from the San Jacinto River waste pits, a Superfund site in Houston, Texas, USA. In all samples, PCDD/Fs and dl-PCBs were detected, and the contaminant concentrations ranged over 5 orders of magnitude.