The Saga of the Electron-Capture Detector
September 1st 2007In 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..
On-line SEC–Py-GC–MS for the Automated Comprehensive Characterization of Copolymers
September 1st 2007Size-exclusion chromatography (SEC) and pyrolysis-gas chromatography (Py-GC) are commonly used to characterize copolymers. SEC is a powerful method to determine the molecular-weight distribution of polymers whereas Py-GC provides valuable information on their chemical composition. The combination of these two techniques could yield combined size and composition information for copolymers or polymer mixtures. A fully automated system was constructed to perform these two-dimensional (2D) characterizations. Several examples of the use of this new technique to comprehensively characterize polymers are described.