flame-ionization detector

A flame-ionization detector (FID) is a type of detector used in gas chromatography. When the gas stream emerging from the chromatography column is mixed with hydrogen and burned, organic substances produce positive ions and electrons in the flame. These ions are collected at electrodes, generating a measurable current. The FID is highly sensitive to hydrocarbons but does not detect carrier gases like nitrogen or highly oxidized materials such as carbon dioxide or water. This detector is often referred to as a "carbon counter" because its response is proportional to the number of carbon atoms in the detected molecule.12