Introduction of water and water-containing solvent mixtures in capillary gas chromatography : II. Wettability of precolumns by mixtures of organic solvents and water; retention gap techniques

Abstract

The wettability of phenyl- and cyanosilylated precolumn surfaces by mixtures of organic solvents and water ( e.g., typical reversed-phase eluents) was tested. Depending on the organic solvent, mixtures with high water concentrations, such as 1-propanol containing up to 70% water, still wet such standard precolumn surfaces. However, when retention gap techniques were applied, another requirement proved to be more limiting: water must evaporate at least as rapidly as the organic solvent, otherwise water is left behind the evaporating solvent mixture and, as water does not wet these surfaces, it floods the capillary. Hence high-boiling solvents are required; azeotropically boiling mixtures facilitate the work. It is shown that 1-propanol with up to 28% water allows the introduction of large volumes by the retention gap technique.