Study of the retention characteristics of calix[4]arene-bonded silica stationary phase and comparison with common phases for HPLC using linear solvation energy relationships

The similarities and differences in retention characteristics of p-tert -butyl-calix[4]arene-bonded and three other silica-based phases have been elucidated by the use of linear solvation energy relationships (LSERs). These phases were investigated in a common mobile phase. The results of LSERs on p-tert -butyl-calix[4]arene-bonded phase shows resemblances and differences to other silica-based reversed-phases. The retention of solutes on all the silica-based phases are dominated by two factors: the solute size and hydrogen bond acceptor basicity. But, for p-tert -butyl-calix[4]arene-bonded phase, the main retention governing factor is the solute size, which contribution accounts for 63% of the variance in log k values. The s coefficient is small, but positive, which is unlike the common reversed phase stationary phases. The r coefficient, which is small and positive, showed the new phase has greater pi-pi interaction to solutes than all other phases, and relatively high selectivity to polyaromatic hydrocarbons. The retention mechanism of the phase, mainly, is a partitioning mechanism.