Similar structured carcinogen substances: Separation and determination of polychlorobiphenyls and organochloride pesticides

Abstract

Polychlorinated biphenyls (PCBs) and organochlorinated pesticides (OCPs) are organic molecules those contain one or more chlorine usually bonded to carbon atoms. In the past, while OCPs were widely used for agricultural purposes and in the fight against epidemic diseases, PCBs had an important area of usage in the industry because of their flame resistant property. The analogous chemical structure of polychlorinated biphenyls and organochlorinated pesticides leads accumulation of them in the same media of living organisms and the environment. The usages of polychlorinated biphenyls and organochlorinated pesticides have been prohibited in many countries due to their harmful effects in terms of human health and the environment. However, the presence of polychlorinated biphenyls and organochlorinated pesticides in the environment continues because of their highly resistant nature to chemical and biological degradation. There are few reported methods dealing with the simultaneous determination of polychlorinated biphenyls and organochlorinated pesticides in the literature. Frequently used techniques for the analysis of these compounds are gas chromatography (GC) and high-performance liquid chromatography (HPLC). The most commonly used technique for the analysis of both these compounds is gas chromatography with electron capture detector (GC-ECD) which is sensitive to chlorine containing compounds. However during the simultaneous analysis of PCBs and OCPs with GC-ECD, the signals overlap giving peaks at the same retention times in the chromatograms. The existence of PCBs as mixtures makes the problem more complex. In order to solve this problem, PCBs and OCPs had been either separated by extraction or by degradation of OCPs. In this article the chemical and physical properties of polychlorinated biphenyls and organochlorinated pesticides, their application areas, effects on the health and environment are explained. Then examples are presented for analysis of PCBs and OCPs individually. Methods developed for simultaneous determination of PCBs and OCPs are also described with a discussion of analytical problems.