Vibration

2014-01-04T13:56:21Z

117.241.176.181: /* Illustration of a multiple DOF problem */

'''Electron-capture mass spectrometry''' ('''EC-MS''') is a type of [[mass spectrometry]] that uses [[electron capture ionization]] (ECI) to form negative [[ion]]s from [[chemical compounds]] with positive [[electron affinity|electron affinities]]. The approach is particularly effective for [[electrophile]]s. In contrast to [[electron ionization]], EC-MS uses low energy [[electrons]] in a [[gas discharge]]. The technique can be used with [[gas chromatography-mass spectrometry]].<ref name="pmid15180565">{{cite journal |author=Leis HJ, Fauler G, Rechberger GN, Windischhofer W |title=Electron-capture mass spectrometry: a powerful tool in biomedical trace level analysis |journal=Curr. Med. Chem. |volume=11 |issue=12 |pages=1585–94 |date=June 2004 |pmid=15180565 |doi= |url=http://www.bentham-direct.org/pages/content.php?CMC/2004/00000011/00000012/0005C.SGM}}</ref>

==Mechanism==
The attachment of a low energy electron can give rise to two possible reactions for the compound, as shown below. Either the compound attaches an electron to form a [[Radical (chemistry)|radical]] [[anion]],

:<math>AB + e^- \to AB^{-\bullet} </math>,

or the compound fragments, resulting in [[electron capture dissociation]] (ECD).<ref>{{cite journal |last=Giese |first=RW |title=Electron–capture mass spectrometry: recent advances |journal=Journal of Chromatography |volume=892 |issue= 1-2|pages=329–346 |publisher= |location= |year=2000 |url= |doi=10.1016/S0021-9673(00)00364-2 |pmid=11045497 |accessdate= }}</ref> ECD forms an anion fragment and a radical fragment

:<math>AB + e^- \to A^{-} + B^{\bullet}</math>.

Fragmentation in ECI has been studied by [[tandem mass spectrometry]].<ref name="pmid10962492">{{cite journal |author=Wei J, Liu S, Fedoreyev SA, Voinov VG |title=A study of resonance electron capture ionization on a quadrupole tandem mass spectrometer |journal=Rapid Commun. Mass Spectrom. |volume=14 |issue=18 |pages=1689–94 |year=2000 |pmid=10962492 |doi=10.1002/1097-0231(20000930)14:18<1689::AID-RCM75>3.0.CO;2-G}}</ref>

==See also==
*[[Electron capture detector]]

==References==
{{reflist}}

[[Category:Ion source]]

{{chemistry-stub}}

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