Some aspects of current techniques for the preparation of capillary columns for gas chromatography

Abstract

Desirable column properties and their relation to different steps in column preparation are discussed. The properties of different capillary materials are compared, the different methods for high-temperature silylation, which are being used to achieve deactivation and wettability, are considered and the advantages of immobilized silicone stationary phases are described. Immobilization leads primarily to improved stationary phase film stability and this is of particular utility in connection with polar columns; some polar silicone gums have a high temperature coefficient of viscosity and may therefore be redistributed on a capillary surface at elevated temperatures, leading to deterioration in column performance. Immobilization very efficiently counteracts such an effect. Silicones containing cyanopropyl and phenyl substitution cannot readily be cross-linked. It is demonstrated that a convenient way to solve this problem is to include some tolyl substitution in the gum that is to be cross-linked.