More cool gadgets: Electron Capture Device

Posted: Mon Jun 14, 2004 6:51 pm

Electron Capture Detector

The electron capture detector is the piece of equipment that measures the types of gasses coming out of the gas chromatograph.

To understand the gas chromatograph, it may be helpful to imagine a football quarterback throwing passes to a receiver downfield. When the receiver catches the ball, a touchdown may be scored. In some cases, the football is intercepted by a member of the opposite team and doesn’t reach the receiver at all.

And what does football have to do with analytical chemistry, and specifically electron capture detectors?

The electron capture detector uses a piece of foil made from radioactive nickel (quarterback) which gives off a stream of beta particles which high-energy electrons (footballs in our analogy). Ordinarily, the electrons reach the receiver on the other side of the ECD, except when a gas gets in the way (interceptor). By throwing lots of electrons each second (about 6,000), even a gas passing through the detector quickly will intercept some of those electrons. When the receiver receives fewer electrons, it generates a lower current. The drop in current is recorded by the computer and analyzed by us.

Interesting facts to make you smarter:
You are exposed to radiation everyday: from the sun, from small amounts of naturally-occurring radioactive rocks, etc. Dentists and doctors cover you with a lead shield when X-raying teeth or broken bones to prevent the very strong X-rays they use from damaging other parts of your body.

Radiation exposure is sometimes measured in “disintegrations per minute”, and sometimes in “curies” (named after Marie Curie, a Nobel Prize winner in chemistry and in physics for her pioneering work with radiation).