Yehl P M, O'Brien T P, Moeder C W, Grinberg N, Bicker G, Wyvratt J
Merck Research Laboratories, Department of Analytical Research, Rahway, New Jersey 07065, USA.
Chirality. 2000 Mar;12(3):107-13. doi: 10.1002/(SICI)1520-636X(2000)12:3<107::AID-CHIR2>3.0.CO;2-Q.
The HPLC separation of the R,S and S,R enantiomers of pyrrolidinyl norephedrine on immobilized alpha-1 glycoprotein (AGP) was investigated. Conditions for the separation were varied using a premixed mobile phase containing an ammonium phosphate buffer and an organic modifier. The influence of mobile phase pH, ionic strength, organic modifier composition, modifier type, and temperature on the chiral selectivity and retention were investigated. The presented data demonstrate that independent phenomena govern the enantioselectivity and retention. Retention is a function of both ion exchange equilibria and hydrophobic adsorption. Thermodynamic data derived from van't Hoff plots illustrates that while enantioselectivity is also enthalpically driven, the magnitude of the enthalpy term is governed by pH. Enantioselectivity has little dependence on ionic strength. Hydrophobic interactions appear to foster hydrogen bonding interactions; the two appear to be mutually responsible for chiral selectivity. The chiral selectivity decreases as the pH is decreased and increases with mobile phase buffer strength.
研究了吡咯烷基去甲麻黄碱的R,S和S,R对映体在固定化α-1糖蛋白（AGP）上的高效液相色谱分离。使用含有磷酸铵缓冲液和有机改性剂的预混合流动相改变分离条件。研究了流动相pH、离子强度、有机改性剂组成、改性剂类型和温度对手性选择性和保留的影响。给出的数据表明，独立的现象控制着对映选择性和保留。保留是离子交换平衡和疏水吸附的函数。从范特霍夫图得到的热力学数据表明，虽然对映选择性也是由焓驱动的，但焓项的大小受pH值控制。对映选择性对离子强度的依赖性很小。疏水相互作用似乎促进了氢键相互作用；两者似乎共同决定了手性选择性。随着pH值降低，手性选择性降低，随着流动相缓冲强度增加，手性选择性增加。
