Analysis of Hydrocarbons in a Hydrogen Atmosphere by Gas Chromatography with Flame Ionization

The ionization response of hydrocarbons In a hydrogen-atmosphere flame was compared to that of a normal flame ionization detector used in gas chromatography. Absolute response in the hydrogen-atmosphere flame lonizatlon detector (HAFID) was found to be two orders of magnitude less than that of the normal FID. This reduced response is attributed both to oxidation of hydrocarbons in the precombustion zone of the flame and to differences In collecting electrode positions in the two detectors. Relative responses for hydrocarbons in the two flames were found to be similar. Both systems responded to hydrocarbons in a manner proportional to the number of carbon atoms in a test compound. These results do not support the postulate that H-atom cracking in the precombustion zone of a flame Is the initial mechanism for the origin of single carbon units in the FID. Relative response similarities did not extend to aromatic or hetero compounds.