4,5-dichloro-chlordene, a new synthetic internal standard for the quantification of toxaphene and chlordane congeners in fish from the barents sea and North Atlantic. Application and experience

1,4,5-exo,7,8,9,10,-10octachlorotricyclo[5,2,1,02,6]dec-3,8-diene (4,5-DCCDD) has been synthesized from trans-nonachlor. The structure was confirmed by mass spectrometry and 1H-NMR. Its use as internal standard for the quantification of polychlorinated bornanes (toxaphene) and cyclodienes (chlordane) was studied. The substance was used for the quantification of selected congeners of both compound classes in cod livers from the Barents Sea and North Sea. Compared to -HCH, 4,5-DCCD was less susceptible to interferences. The chemical and physical properties were comparable to those of toxaphene and chlordane. It eluted within the same fraction as both compound classes. 4,5-DCCD is not present in technical chlordane, can be separated by capillary gas chromatography from other compounds present in real samples and tolerates sulfuric acid in the sample clean-up.