Multifunctional zwitterion-exchange stationary phase for HPLC

A zwitterion-exchange stationary phase (ZIXSP) was prepared for the separation of the mixture of organic bases, organic acids and amino acids by high performance liquid chromatography (HPLC). It was synthesized by the reaction of cyanuric chloride with sulfanilic acid and then bonded onto the silica gel on which the silane coupling agent was prebonded. The chromatographic behaviours of the prepared ZIXSP revealed that the capacity factors of each analyte varied with the pH value of the mobile phase. By applying the concept of acid-base equilibrium the correlation between the capacity factor on the ZIXSP and pH of the mobile phase could be explained reasonably. Based on our results, it is concluded that ZIXSP is a zwitterion exchanger that additionally provides pi-pi charge-transfer interaction and hydrophobic interaction functions.