Electron capture detector 2606066 215335828 2008-05-27T19:23:43Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. The '''electron capture detector''' (ECD) was invented in [[1957]], by [[James Lovelock|Dr. James E. Lovelock ]].<ref> {{cite journal | title = A sensitive detector for gas chromatography | author = J. E. Lovelock | journal = Journal of Chromatography A | year = 1958 | volume = 1 | issue = 1 | pages= 35–46 | doi = 10.1016/S0021-9673(00)93398-3 }}</ref> It is a device for use in [[Gas-liquid chromatography|gas chromatography]] that can detect tiny amounts of chemical compounds in the atmosphere and elsewhere. The electron capture detector is used in detecting electron-absorbing components in the output stream of a [[gas chromatograph]]. 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 [[Electric current|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 an [[Flame ionization detector|FID]], and one million times more sensitive than a [[Thermal conductivity detector|TCD]], 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 femtograms per second (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 ([[Parts_per_notation|ppt]]), thus revolutionizing our understanding of the atmosphere and pollutants. ==References== <div class="references-small"><references/></div> ==Reviews== *{{cite journal | title = Selective detectors in gas chromatography | author = M. Krejči and M. Dressler | journal = Chromatographic Reviews | year = 1970 | volume = 13 | issue = 1 | pages= 1–59 | doi = 10.1016/0009-5907(70)80005-9 }} *{{cite journal | title = Electron capture detection in gas chromatography | author = E. D. Pellizzari | journal = Journal of Chromatography A | year = 1974 | volume = 98 | issue = 2 | pages= 323–361 | doi = 10.1016/S0021-9673(00)92077-6 }} *{{cite journal | title = The electron capture detector | author = J.E. Lovelock | journal = Journal of Chromatography A | year = 1974 | volume = 99 | issue = 1 | pages= 3–12 | doi = 10.1016/S0021-9673(00)90840-9 }} [[Category:Measuring instruments|Electron Capture Detector (ECD)]] [[Category:Gas chromatography]] [[de:Elektroneneinfangdetektor]] [[es:Detector de captura de electrones]]