The Adsorption of a Modifier from the Mobile Phase on to the Column Packing Surface and its Effect on Retention in Gas Chromatography (GC)

The adsorption of a modifier (methanol) from the mobile phase on to a column packing surface and its influence on the retention of aliphatic hydrocarbons (C₆-C₁₂) and of benzene and some of its derivatives has been examined. Prior to such adsorption, the methanol adsorption isotherm was measured chromatographically by frontal analysis methods. A reduced retention of the compounds examined was observed as the concentration of adsorbed methanol increased. In addition, it was established that increasing concentrations of adsorbed methanol on the column packing surface led to a decrease in the selectivity of the latter.