Electron capture detector

The device was invented in 1957 by James Lovelock[1][2][3][4] and is used in gas chromatography to detect trace amounts of chemical compounds in a sample.

[5][6][7] The electron capture detector is used for detecting electron-absorbing components (high electronegativity) such as halogenated compounds in the output stream of a gas chromatograph.

The ECD uses a radioactive beta particle (electron) emitter in conjunction with a so-called makeup gas flowing through the detector chamber.

As the sample is carried into the detector by the carrier gas, electron-absorbing analyte molecules capture electrons and thereby reduce the current between the collector anode and a cathode.

[citation needed] This made it possible to detect halogenated compounds such as pesticides and CFCs, even at levels of only one part per trillion (ppt), thus revolutionizing our understanding of the atmosphere and pollutants.

Schematic of an electron capture detector for a gas chromatograph with a 63 Ni source.
Electron capture detector developed by James Lovelock in the Science Museum, London
Electron capture detector, Science History Institute