Thermionic Ionization Detector with Lanthanum Hexaboride/Silicon Dioxide Thermionic Emitter Material for Gas Chromatography

Optimizing nitrogen-phosphorus detector gas chromatography for pesticide analysis

“…Two theories have been offered to explain ionization: a gas phase process (Kolb and Bischoff, 1974; Kolb et al, 1977) and a surface ionization mechanism (Patterson, 1978;Olah et al, 1979). Negative surface ionization is consistent with the finding that the surface electronic "work function", the amount of energy required to remove an electron from the surface, is critical, whereas the source elemental composition is not (Fujii and Arimoto, 1985).…”

Spectroscopic investigation of the mechanisms of the alkali bead detector for gas chromatography

“…In the gas phase ionization proposal of Kolb and Bischoff, rubidium atoms are assumed to leave the bead by evaporation. This assumption is not consistent with the observation of a good sensitivity of beads containing nonvolatile salts (4,5). Therefore, as an alternative to gas phase ionization, negative surface ionization of the radicals produced in the plasma was proposed by Patterson (6) for a rubidium-containing ceramic bead, by Olah et al (7) for a rubidium-containing glass bead (similar to the bead as introduced by Kolb and Bischoff), and by Fujii and Arimoto (5) for a LaBn bead.…”

“…Therefore, as an alternative to gas phase ionization, negative surface ionization of the radicals produced in the plasma was proposed by Patterson (6) for a rubidium-containing ceramic bead, by Olah et al (7) for a rubidium-containing glass bead (similar to the bead as introduced by Kolb and Bischoff), and by Fujii and Arimoto (5) for a LaBn bead. In the theory of negative surface ionization the degree of ionization at thermal equilibrium is described as (5) n_/n0 = g-/g0e^-*V*T (5) where n0 and rc_ are the densities of neutral and negative species (OH radicals for the background current, as suggested by Olah et al (7) and CN/P0/P02 radicals for the signal current) desorbed from the negative surface at temperature T, 4> is the work function of the surface, Ea is the electron affinity of the species, and g0 and g. are the statistical weights of the neutral and negative species, respectively. The rubidium atoms in the bead are responsible for a reduction of the work function of the glass.…”

Analytical techniques for trace organic compounds - II. Detectors for gas chromatography

“…Although the detailed mechanism of operation is still under investigation, it is believed that ion current is generated by thermionic emission of negatively-charged particles from the surface of the hot bead (ref. 19). Highly electronegative CN radical and PO radical, found in the plasma, are the probable species forming negative ions for nitrogen and phosphorus containing compounds, respectively.…”