Separation Mechanism Of Chiral Stationary Phase Based On Quinine And Crown Ether For The Direct Stereoselective Separation Of Amino Acids

Amino acids are essential nutrients for human beings. The chiral separation of amino acids have received extensive attention. Chromatography has been widely used with the advantage of high efficiency, high selectivity and easy operation. Since the synergistic effect of ion exchange and complexation, a new novel chiral stationary phase combining quinine and crown ether(QN-CR CSP) has a good chiral recognition of amino acids.The influence of the composition of mobile phase on the chiral recognition of amino acids by QN-CR CSP was investigated. The results showed that the chiral recognition of acidic samples by QN-CR CSP mainly depends on the anion exchange interaction. Quinine and the complex formed by crown ether and cation in mobile phase act synergistically on the chiral recognition of acidic samples. Primary amines were separated by complexation with crown ether, whereas the amino acids were separated by the the synergistic effect of ion exchange and complexation.The adsorption isotherm of Trp on QN-CR CSP was moduled to study the retention behaviour of amino acids. The anion in mobile phase competed with amino acid to complex with crown ether. The competition ability increases with the increases of cationic diameter.The ion exchange and complex exchange between samples and QN-CR CSP result in local salt concentration fluctuation which will give rise to experimental error. According to the structural feature of QN-CR CSP, a new adsorption isotherm was built based on Bi-Langmuir equation and validated by studying the adsorption isotherm of Trp. The chrial recognition by QN-CR CSP depends on ionic exchange and complex exchange.The model is of significance in understanding the chiral retention behavior of QN-CR CSP and optimization of the stationary phase structure.