1.Preparation and Characterization of a Novel Isatin Derivative of β-Cyclodextrin-bonded SBA-15 Stationary Phase for HPLC
Yang ZHANG ; Laisheng LI ; Biaoping CHEN ; Rendan ZHOU ; Guizhen NIE
Chinese Journal of Analytical Chemistry 2014;(3):375-383
An isatin derivative ofβ-cyclodextrin Schiff base was first synthesized by the condensation reaction between the carbonyl group of isatin and ethylenediamino group of the mono-substituted β-cyclodextrin. The Schiff base ligand was chemically linked to homemade ordered mesoporous SBA-15 silica gel via 3-( triethoxysilyl) propyl isocyanate coupling agent. In this way, a novel isatin derivative of β-cyclodextrin-bonded SBA-15 stationary phase ( ISCDP) was prepared for HPLC. Its chemical and physical parameters were characterized by infrared spectroscopy, mass spectroscopy, elemental analysis, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and BET specific surface area analysis. The basic chromatographic property of ISCDP was evaluated by using polar halogenated uracils and disubstituted benzene positional isomers as solute probes in reversed-phase chromatography. ISCDP was also used to enantioseparate twoβ-blocker drugs in polar organic mode and two dansyl amino acids in reversed-phase mode, respectively. The related chromatographic separation mechanism was also discussed. Above studies were expected to provide experimental basis for the practical application of ISCDP in the future. The results showed that the introduction of isatin indole ring could enhanced the reversed-phase chromatographic separation ability of ISCDP for halogenated uracils within 7 min. The new packing also exhibited high stereoselectivity for the position isomers of nitroaniline, aminophenol and benzenediol, in which the para isomers were finally eluted due to strong inclusion interaction between the isatin derivative of β-cyclodextrin ligand and the isomers. Meanwhile, the introduction of isatin indole ring could also improve the chiral separation ability of ISCDP. For example the fast enantioseparations of chiral β-adrenergic blockers and dansyl-amino acids on ISCDP were achieved within 20 min (Rs>1. 3). Obviously, besides hydrophobicity, various synergistic interactions could enhance the separation selectivities of the new stationary phase for chiral and achiral analytes, including dipole-dipole, hydrogen bonding,π-π and inclusion interactions. The ordered pore structure of SBA-15 facilitated to fast and efficient separation and analysis for drugs with good permeability and low mass transfer resistance.