Preparation and characterization of bonded stationary phases of nitrogen-containing crown ether for high-performance liquid chromatography

Silica gel bonded phases with a nitrogen-containing crown ether were synthesized via a three-step reaction on the surface of porous silica. The bonded molecular structure was characterized by chemical and instrumental analyses. The bonded phases possess complexing ability with copper ion and weak hydrophobicity. The retention behaviour of polar disubstituted benzene derivatives and amino acids on the bonded phases was studied using methanol and/or aqueous solution with acetate buffer and copper ion as mobile phases. When copper cations are added to the mobile phase at pH 5, positive charges are generated on the surface of the stationary phase and some electrostatic interaction occurs between polar organic compounds and the stationary phase. The Chromatographic retention of the polar solutes is controlled mainly by dipolar and electrostatic interactions, and is less affected by hydrophobic interactions.