Immunochemical measurement of polychlorinated biphenyl compounds in transformer oils

Polychlorinated biphenyl (PCB) contaminated insulating oils represent a serious environmental problem to the power-transmission industry and there is much ongoing work directed at decommissioning such oils. The correct identification of contaminated oils is a key aspect of any decommissioning program. However, current analytical approaches are costly, complex, slow or are non-specific. This paper describes a combined sample preparation and PCB-specific immunoassay method for the measurement of these compounds in transformer oils that overcomes these shortcomings. A key aspect of the work centered on manipulating the sample such that it was compatible with the immunoassay process. Sample pretreatment using octadecyl carbon (C18) sorbents or washing with KOH/ethanol-sulfuric acid proved suitable with PCB recoveries of ⩽100%. Aroclor (PCB mixture) contaminated transformer oils were assayed using both an in-house immunoassay and a commercially available test kit for PCB in soil and water. The in-house method proved reliable for the measurement of oils containing >35 μg mL^-1 Aroclor, but overestimated Aroclor levels in oils containing <10 μg mL^-1 analyte. The commercial kit tended to underestimate Aroclor concentrations yielding values between 23 and 63% of that expected. These differences were attributed to the different antibody preparations employed