Ionization in flames. II. Mass-spectrometric and mobility analyses for the flame ionization detector ||

Abstract
An earlier paper by two of the present authors gave an electrical theory of the flame ionization detector. Results of mass spectrometric and mobility studies of the positive ion species in the detector are presented here. For all organic additives, at concentrations around 1 %, the charge is carried by a group of ions, H 30+(H20 )w, where n is a small integer. These ions behave effectively as a single ion in mobility experiments because an equilibrium distribution is maintained as they drift towards the collector electrode. At low concentrations of additive a second group of ions, N H ^(H 20 )n, becomes comparable in number with the H 30 +(H20 )n group. This alters the electrical characteristics of the detector but does not affect its linearity.