| Electron Capture Detector |
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Information AboutElectron Capture Detector |
| CATEGORIES ABOUT ELECTRON CAPTURE DETECTOR | |
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| electron capture detector ecd | |
| gas chromatography | |
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The ECD uses a radioactive Beta Particle (electrons) emitter -- a typical source contains a metal foil holding 10 milli Curie s of Nickel-63. The electrons formed are attracted to a positively charged Anode , generating a steady Current . As the sample is carried into the detector by a stream of Nitrogen or a 5% Methane /95% Argon ) mixture , analyte molecules capture the electrons and reduce the current between the collector anode and a Cathode . The analyte concentration is thus proportional to the degree of electron capture, and this detector is particularly sensitive to Halogen s, organometallic compounds, nitriles, or nitro compounds. SENSITIVITY The ECD is 10-1000 times more sensitive than the FID ( Flame Ionization Detector ), and one million times more sensitive than a Thermal Conductivity Detector , but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds. The detection limit for electron capture detectors is 5 fg/s, and the detector commonly exhibits a 10,000-fold linear range. This made it possible to detect halogenated compounds such as pesticides and CFC s, even at levels of only one part per trillion (ppt), thus revolutionizing our understanding of the atmosphere and pollutants. |
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