Discharge ionization detector

A discharge ionization detector (DID) is a type of detector used in gas chromatography.

Principle

A DID is an ion detector which uses a high-voltage electric discharge to produce ions. The spark ionizes helium atoms that are mixed with components as they elute from the GC's column, causing the components to become ionized. The ions produce an electric current, which is the signal output of the detector. The greater the concentration of the component, the more ions are produced, and the greater the current.

Application

DIDs are sensitive to a broad range of components. In Air Separation plants they are used to detect the components CO; CH2; C+; N2; O2 in Argon product in ppm range.

DIDs are non-destructive detectors. They do not destroy/consume the components they detect. Therefore they can be used before other detectors in multiple-detector configurations.

DIDs are an improvement over Helium ionization detectors in that they contain no radioactive source.

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