Electron-capture detector environmental applications

A third type of detector, required for some environmental and biomedical applications, is the electron capture detector (ECD). This detector is especially useful for large halogenated hydrocarbon molecules since it is the only one that has an acceptable sensitivity for such molecules. Thus, it finds special utility in the analysis of halogenated pesticide residues found in environmental and biomedical samples. 

The structure-selective, electron-capture detector (ECD) is the second most widely used ionization detector [254,293-295]. It owes its popularity to its unsurpassed sensitivity to a wide range of environmentally important and biologically active compounds. Examples of general applications include the determination of pesticides and industrial chemicals in the environment, assessment of the fate of ozone-depleting chemicals in the upper atmosphere and the determination of drugs and hormones in biological fluids. 

With the application of electron-capture (EC) and micro-coulometric detection to gas chromatograph effluents from i960, the era of the measurement of nothing in everything had arrived and the environmental controversy was truly on. It was easier to make an effective EC detector than to interpret the analytical results correctly and many of the identifications of chlorinated insecticide (OC) residues made in the early 1960s are undoubtedly suspect, especially since it was found in 1966 that widespread polychlorobiphenyl (FCB) contamination in the bio-sphere can simulate OC in gas chromatographic analysis. 

Although polychlorinated biphenyls (PCBs) were first synthesized in 1881 and introduced into industrial use as electrical insulators in the 1920s, they were detected in environmental samples only some 35 years later in 1966 by Jensen 0ensen 1972 Jensen et al. 1972). This discovery was facilitated by the development of the electron-capture (EC) detector in GC, and it also illustrates an early example of the application of MS to the tentative identification of environmental contaminants. Since that date, PCBs have become recognized as virtually universal contaminants of environmental samples from all parts of the world. 

---