METHANE FORMATION BY FLAME-GENERATED HYDROGEN-ATOMS IN THE FLAME IONIZATION DETECTOR

The precombustion degradation of organic compounds in the flame ioniza tion detector has been studied (1) by heating the additives in hydroge n in a quartz capillary and analyzing the reaction products by GC and (2) by following the degradation of the additives in a hydrogen name, by means of a thin fused silica probe inserted from the bottom of the flame and connected to the ion source of a mass spectrometer, The resu lts show that the thermic hydrogenolysis of hydrocarbons at name tempe ratures produces mixtures of methane, ethene, and ethyne, In the name, however, ethyne, benzene, isobutane, and conceivably all hydrocarbons are quantitatively converted into methane at temperatures below 600 d egrees C, that is, before the proper combustion has started, The split ting of the C-C bonds is preceded by hydrogenation of double and tripl e bonds and aromatic rings, The reactions, no doubt, are caused by hyd rogen atoms, which are formed in the burning hydrogen and which diffus e into the inner core of the name, The quantitative formation of metha ne appears to explain the ''equal per carbon'' rule for the detector r esponse of hydrocarbons, since all carbons are ''exchanged'' for metha ne molecules.