Gas chromatography coupled with a flame ionization detector (GC-FID) is a widely used analytical technique.
The column outlet passes through a flame produced by the combustion of two gases and maintained by the make up at a voltage of a hundred volts.
An FID normally uses a hydrogen / air flame and ionizes the sample which is pushed into and out of the column by the carrier gas. The ions produced are collected using a bias voltage. An electrical signal is generated and is also measured, allowing the compounds leaving the column to be quantified.
The FID is sensitive with a wide range of detectable organic compounds and is therefore not very specific. One drawback is that it destroys the sample during its passage through the flame.