engleski

Validation of a congener specific method for analysis of polychlorinated biphenyls in soil and sediments

Two critical steps in quantitative congener specific analysis of polychlorinated biphenyls (PCBs) in soil/sediment samples are efficient extraction from the matrix and separation of individual compounds before detection. High resolution gas chromatographic techniques enable efficient separation of PCB congeners selected either as congeners of a typical structure and high toxicity or congeners taken to be typical and representative of the most widely used commercial PCB mixtures. A capillary gas chromatographic method was developed to determine total PCBs and individual PCB congeners, including six congeners most frequently found in environmental samples ( PCB-28, PCB-52, PCB-101, PCB-138, PCB-153 and PCB-180), in soil and sediments. PCBs were accumulated from soil/sediment samples by sonicated multiple extraction with a 1:1 acetone/n-hexane mixture. The extracts were purified by treatment with copper powder, mercury and sulphuric acid. The GC analysis was performed on a 60 m x 0.25 mm i.d. SPB-5 capillary column using electron capture detection (63Ni ECD). In order to determine the linearity range of the ECD for individual PCB congeners a series of calibration standard solution was injected into GC covering a concentration range of 1.0-1.5 orders of magnitude (1-50 ng/mL). The recovery of individual congeners from soil/sediment was evaluated and the repeatability of the results was tested by replicate analyses of two certified reference materials (CRM): CRM 481 - an industrial soil with certified mass fractions of eight and indicative values of mass fractions of four PCB congeners at mg/kg level, and CRM 536 - a fresh water harbour sediment with certified mass fractions of 13 PCB congeners at ľg/kg level. The recoveries of PCB-28, PCB-52, PCB-101, PCB-138, PCB-153 and PCB-180 congeners from certified industrial soil were 71-115%, depending on compound, and relative standard deviations of the repeatability of the results ranged from 10% for PCB-101 to 42% for PCB-28. At lower mass fractions in certified sediment sample the recoveries were lower (56-86%) but the repeatabilities of the results were more uniform (18-24%). The method was applied for determination of individual PCB congeners in airport soil samples containing more than 1 mg/kg dry weight of total PCBs.

PCBs; soil/sediment; congener specific analysis

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