# What is an electron capture detector?

Sep 17, 2015

An electron capture detector (ECD) is a device that detects molecules in a gas when electrons are captured from a beta emitter.

#### Explanation:

The ECD uses a beta emitter such as $\text{^63"Ni}$ to produce electrons.

The emitted electrons collide with the molecules of a carrier gas.

The collisions create many more free electrons from the gas molecules.

The electrons are accelerated towards a positively charged electrode, generating a current that is always present as a background signal.

(from chemwiki.ucdavis.edu)

Any electron-absorbing molecules (such as compounds containing halogens, phosphorus, and nitro groups) in the carrier gas capture electrons and reduce the background current. current.

The electronics convert the signal into peaks that are proportional to the quantity of electrophilic compounds.