Carrier gas containing the compounds from the column passes directly into mixing teewhere H2 for combustion and methanization is added. At the heated flame tip with theFID tower, this gas stream is bathed in a cylindrical flow of combustion air, and the H2 /O2 flame is ignited.Within this flame, the following general reactions occur : (reactions are left unbalanced forsimplicity)

H2 + O2 => H2O + Heat

and

CH4 + O2 + Heat => CHO + + H2O + e –

and

C3H8 + O2 + Heat => 3CHO + + H2O + 3e –

Depending upon operating parameters, this reaction releases electrons until the endreaction products are reached. These electrons are collected and the resulting currentmeasurement is used for quantification.The net result is, in simplest terms, that electrons are released in direct proportion to the number of carbon atoms present.