Preparation of p-tert-butyl-calix[8]arene bonded silica stationary phase and separation for steroid hormone medicines

p-tert-Butyl-calix[8]arene bonded silica (CBS) gel stationary phase for high-performance liquid chromatography was first prepared by condensation reaction between chloropropyl bonded silica (CPS) and phenolic sodium salt of p-tert-butyl-calix[8]arene on solid phase surface. A new bonded stationary phase was characterized by elemental analysis, Fourier transform infrared (FTIR) analysis, and thermal analysis. The chromatographic behaviors on CBS for steroid hormone medicines were studied. The effect of mobile phase variables, such as methanol content, pH, ionic strength, and buffer composition on the retention of solutes was investigated. The retention behaviors of steroid hormone medicines on CBS were compared with that on CPS and ODS. The retention mechanism of steroids on new stationary phases was also discussed. The results indicate that CBS exhibits pi-pi, hydrogen-bonding, dipole-dipole interaction, and inclusion complexation besides hydrophobic interaction. Compared with ODS, separation speed increases, and consumption of organic solvent decreases. Steroid hormones were baseline separated with a half time on CBS opposed to ODS.