How Reliable Is the Laboratory Analysis of Polychlorinated Biphenyls (PCBs) in Soil?

Polychlorinated biphenyls (PCBs) are a group of manufactured organic compounds that include various isomers, or congeners. They were widely used in the past, especially as coolants and lubricants for electrical equipment. Although production of PCBs was banned by the Stockholm Convention on Persistent Organic Pollutants in 2001 due to their environmental toxicity, environmental contamination by PCBs still remains an issue today because they are chemically stable and resistant to degradation in the natural environment. Extraction and quantification of PCBs from a soil are not easy because of their strong adsorption to clay materials. Referring to EN 16167: 2012, and using the sample prepared for an ISO ring test by Federal Institute for Materials Research and Testing (BAM), this study examined the accuracy or reliability of gas chromatography with electron-capture detection (GC-ECD) and gas chromatography with mass selective detection (GC-MS) for characterizing PCBs. In addition, different columns, specifically, DB-5MS and HT8-PCB were used to cross-check the analytical results. The results illustrated that both GC-ECD and GC-MS can be used to analyze PCBs with an acceptable accuracy. Analytical values of concentrations of different congeners, specifically, TrCB#28, TeCB#52, PeCB#101, PeCB#118, HxCB#138, HxCB#153, HpCB#180, are dependent on analytical approach due to the differences in standard materials being used and interference between congeners. Compared with the analytical approach, the effects of column are negligible. Comparisons with the results obtained from other laboratories demonstrated that the skillfulness of operators and detailed conditions for extraction could be the major reasons that induce significant analytical errors.