Thermodynamic consideration of the retention mechanism in a poly(perfluoroalkyl ether) gas chromatographic stationary phase used in packed columns

Abstract

Abstract Retention volumes of fifteen hydrocarbons were measured in columns containing several concentrations of a commercial poly(perfluoroalkyl ether), Fomblin Y HVAC 140/13, as the stationary phase. Two different types of packing were studied: one of them employed pre-silylated Chromosorb P AW DMCS as the solid support and the other type was prepared by coating the stationary phase on Chromosorb P AW and silylating on-column. On-column silylated columns showed unequivocal symptoms of partial deactivation; retention volumes changed regularly with the content of stationary phase in pre-silylated columns. Analysis of retention in pre-silylated columns indicates that a mixed mechanism (partition and adsorption onto the gas-liquid interface) is operative. The systems hydrocarbon-perfluorocompound show pronounced positive deviations from the ideal behaviour that can be attributed to repulsion between the hydrocarbon and the perfluorocompound segments.