Chromatographic Properties of Different Methyl—Phenyl (1:1) Substituted Silicone Stationary Phases for Open-Tubular Gas Chromatography

The influence of different configurations of silicones having 50% methyl and 50% phenyl substitution on chromatographic properties, such as polarity and thermal stability, has been systematically investigated. Polysiloxanes composed of dimethyl and diphenyl units show very low levels of column bleed at temperatures up to 370°C, while polymers having methyl—phenyl substitution show severe bleeding at this temperature. The polarity of the latter polymers, as reflected by Kováts indices, is higher than for the polymers composed by dimethyl—diphenyl unit