Detector Systems

Electron capture detector (ECD)

Figure 7-5

y

Anode

Anode Purge

Vent

Plated 63Ni Surface

Makeup Gas Adapter

Nickel Plating

Fused Silica Liner

Makeup Gas

Column

Electron Capture Detector (ECD)

The electron capture detector (ECD) cell contains Ni, a radioactive isotope emitting high•energyelectrons (µ•particles).These undergo repeated collisions with carrier gas molecules, producing about 100 secondary electrons for each initial µ•particle.

Further collisions reduce energy of these electrons into the thermal range. These low energy electrons are then captured by suitable sample molecules, thus reducing total electron population within the cell.

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