Study on the chromatographic behavior of water-soluble vitamins on p-tert-butyl-calix[8]arene-bonded silica gel stationary phase by HPLC.

In this paper, the chromatographic behavior of some water-soluble vitamins was studied on a new p-tert-butyl-calix[8]arene-bonded silica gel stationary phase (CABS, 5mum particle size, the bonded amount 0.071mmolg(-1)) by using vitamin standards as probes for HPLC. The comparative study of the separation of these compounds was done by using CABS and ODS as stationary phases under the same chromatographic conditions. The better separation of six vitamins including: B(1), B(2), B(6), B(12), C, and nicotinic acid (B(5)), on CABS can be achieved by using isocratic mode with methanol-phosphate buffer (25:75, (v/v)) as mobile phase within 20min. The results show that the calix[8]arene-bonded phase exhibits high selectivity for water-soluble vitamins. We found that the elution order of B(2) (12.08min) and B(12) (16.42min) on CABS was very different from that of B(12) (7.76min) and B(2) (18.47min) on ODS, which indicate that different retention mechanisms exist in the chromatographic processes of the two stationary phases. According to the chromatographic data, it can be concluded that various chromatographic retention mechanisms are responsible for the separation of above compounds on CABS, such as hydrophobic interaction, hydrogen bonding interaction, and pi-pi interaction. The new packing has two advantages over ODS. On one hand, the polar and ionized analytes, such as C and B(5), exhibited stronger affinities to CABS because of hydrogen bonding interaction. On the other hand, the retention of B(2) and B(12) became shorter on CABS with weaker hydrophobicity in comparison with ODS. The new material exhibits the promising application in the separation of water-soluble vitamins.