Adsorptive properties of N-2-cyanoethyl-N-methylaminosilica in high-performance liquid chromatography

Net retention volumes per gram of N-2-cyanoethyl-N-methylaminosilica have been measured for a large number of mono- and disubstituted benzenes, some mono-substituted (cyclo)hexanes and a number of unsubstituted polycyclic aromatic hydrocarbons, using n-hexane, methylene chloride and a mixture of both solvents as eluent at 25° and 43.5°. The retention data are interpreted in terms of the semi-empirical adsorption model, developed by Snyder for bare adsorbents. The effects of adsorbent deactivation (due to the amination and the adsorption of the cyano group to the silica), temperature, solute and eluent localization, change of charge distribution in the solute molecule by substituents and mode of adsorption of the solute on retention are discussed.