Determination of the polychlorinated biphenyl substitute Ugilec (tetrachlorobenzyltoluenes) in fish

A method is presented for the determination of tetrachlorobenzyltoluenes (TCBTs) in fish. TCBTs represent the major constituents of Ugilec, which is commonly used as a substitute for polychlorinated biphenyls (PCBs) in underground mining. The compounds are extracted from the freeze-dried material together with fat and other lipophilic substances. Gel chromatography on Bio-Beads S-X3 is used for removal of fat followed by adsorption chromatography on silica gel (1.5% water). Combined gas chromatography-mass spectrometry employing an ion trap detector is used for the separation and detection of the compounds. The developed procedure provides identification and determination of TCBTs even in the presence of an excess amount of PCBs. The application of the procedure to the investigation of fish caught in rivers from areas with extensive mining indicates that Ugilec has already found its way into the food chain.