Preparation and HPLC evaluation of a new 1,3-alternate 25,27-bis-[p-chlorobenzyloxy]-26,28-bis-[3-propyloxy]-calix[4]arene silica bonded stationary phase.

The 1,3-alternate 25,27-bis-[p-chlorobenzyloxy]-26,28-bis-[3-propyloxy]-calix[4]arene-bonded silica gel stationary phase was synthesized, structurally characterized, and used as a selector in high performance liquid chromatography. Selectivity studies on that phase used aromatic positional isomers, alkylbenzenes, polynuclear aromatic hydrocarbons, sulfonamides, and non-steroidal anti-inflammatory drugs as analytes. The effects of organic modifier content and pH of the mobile phase on retention and selectivity of selected aromatic positional isomers were studied. Selectivity comparisons of the novel phase vs. 1,3-alternate 25,27-di-[benzyloxy]-26,28-bis-[3-propyloxy]-calix[4]arene phase and commercially available RP-Phenyl phases were performed. The retention mechanism was also discussed. The results indicated that the calixarene stationary phase behaves like a reversed-phase packing; however, other retention mechanisms seem to be involved in the separation process.