Peter J.T. Morris

In addition to the universal detectors used in gas chromatography (GC), selective detectors have also played an important role in the rapid spreading of the utilization of the technique. Probably the most important selective GC detector is the electron-capture detector, with a very high sensitivity to organic compounds containing chlorine and fluorine atoms in their molecules. The electron-capture detector had a vital role in environmental protection and control - its use helped to prove the ubiquitous presence of chlorinated pesticides in nature and halocarbons in our atmosphere, and made us aware of the global extent of pollution. It was the electron-capture detector that made concentration ranges of parts-per-billion (ppb: 1:109) or even parts-per-trillion (ppt: 1:1012) detectable. Today, these terms are used routinely without realising how formidable such a sensitivity really is: 1 ppb means that a spaceship (or a UFO, depending upon one's inclination) could pick up a particular family of six from..