Electron Capture Detector (ECD) – Working

Hi friends, in this post we are going to learn about electron capture detector in detail. We will also see the construction and working of electron capture detector with diagram.

Electron Capture Detector :

Electron Capture Detector
Electron Capture Detector

Construction and working of electron capture detector:

The diagram shows electron capture detector used in chromatographic analysis of environmental samples. This detector operates similar to proportional counter used for X-ray measurement. In this detector, the effluent from the column is passed over a ß emitter (Ni-63). An electron from ß emitter causes ionization of carrier gas and production of a burst of electrons. In the absence of organic compounds, a constant standing current between a pair of electrodes results from this ionization process. However in presence of organic compounds the current decreases significantly. The response of this detector is nonlinear unless the applied potential across the detector is pulsed.

The electron capture detector is highly sensitive molecules containing electro-magnetive functional groups like halogens, peroxides, nitro groups; it is insensitive to the functional groups like amines, alcohols, and hydrocarbons. Hence it is a powerful tool in the determination of chlorinated insecticides.

Advantages of electron capture detector:

  • 1)      Electron capture detector is highly sensitive.
  • 2)      Non destructive to the sample.

Disadvantages of the electron capture detector:

  • 1)      Highly non linear response.
Electron capture detector
Electron capture detector
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