Determination of coplanar and ortho substituted PCBs in some sewage sludges of Switzerland using HRGC/ECD and HRGC/MSD

The three most toxic coplanar PCB congeners PCB 77, 126 and 169 as well as 7 mono-and di-ortho-PCBs (PCB 28, 52, 101, 118, 153, 138, 180) were measured in 19 sewage sludges. Concentrations of the coplanar PCBs ranged between 231–5050 ng/kg dw for PCB 77, 43–1511 ng/kg dw for PCB 126 and 29–273 ng/kg dw for PCB 169. Comparable results were obtained with mass selective detection in the single ion monitoring mode (MSD-SIM) except for PCB 169, where MSD-SIM was less sensitive than ECD. The sum of the 7 mono-and di-ortho-PCBs, which are routinely measured as representatives of the PCB fraction, reached levels between 43–550 μg/kg dw and agreed well with results previously obtained in our laboratory. Based on our data, a selective accumulation of the coplanar PCBs could not be observed. Sludges that received industrial effluents clearly showed higher PCB levels than rural ones. Finally, calculation of TEQ equivalents of the coplanar PCBs in the sewage sludges revealed that, based on application rates normally used in Switzerland, the contribution of the sludges to soil pollution seems to be of minor importance.