Owens P K, Fell A F, Coleman M W, Berridge J C
Pharmaceutical Analysis Research Unit, Pharmaceutical Chemistry, School of Pharmacy, University of Bradford, United Kingdom.
Chirality. 1997;9(2):184-90. doi: 10.1002/(SICI)1520-636X(1997)9:2<184::AID-CHIR20>3.0.CO;2-I.
The chromatographic resolution of rac-doxazosin using reversed-phase high performance liquid chromatography (HPLC) with the chargeable chiral mobile phase additive, carboxymethyl-beta-cyclodextrin (CM-beta-CD), is described. The effects of different modifiers (acetonitrile, methanol and tetrahydrofuran), pH, temperature, and cyclodextrin concentration were investigated to a) assess the key chromatographic parameters for subsequent chemometric optimisation, and b) explore the enantioselective mechanism. Assuming a 1:1 complex between each doxazosin enantiomer and CM-beta-CD, studies of the relationship between the capacity factors (k') and functions of CM-beta-CD concentration indicate that the mechanisms for retention and chiral selectivity are comparable with those proposed earlier by Sybilska et al. Stability constants (KG) calculated for rac-doxazosin complexed with CM-beta-CD (647 +/- 55 and 594 +/- 45 M-1 for each enantiomer respectively) are significantly larger than those calculated for the barbiturates complexed with beta-CD (ca. 101-108 M-1). Investigations on pH indicate an ionic or ino-pair interaction between the anionic CM-beta-CD and the cationic doxazosin enantiomers. A central composite design was used to optimise the key chromatographic parameters: pH, methanol (v/v) and CM-beta-CD concentration. The Kaiser peak separation index, Pi, was used for the response function. The predicted response for this chiral separation has been compared with that observed experimentally and samples of the four-dimensional response surface have been assessed for their value in showing robustness.
描述了使用带电荷的手性流动相添加剂羧甲基-β-环糊精（CM-β-CD）的反相高效液相色谱（HPLC）对消旋多沙唑嗪进行色谱拆分。研究了不同改性剂（乙腈、甲醇和四氢呋喃）、pH值、温度和环糊精浓度的影响，以a）评估后续化学计量学优化的关键色谱参数，以及b）探索对映体选择性机制。假设每种多沙唑嗪对映体与CM-β-CD之间形成1:1络合物，容量因子（k'）与CM-β-CD浓度函数之间关系的研究表明，保留和手性选择性机制与Sybilska等人先前提出的机制相当。计算得到的与CM-β-CD络合的消旋多沙唑嗪的稳定性常数（KG）（每种对映体分别为647±55和594±45 M-1）明显大于计算得到的与β-CD络合的巴比妥类药物的稳定性常数（约101-108 M-1）。对pH值的研究表明，阴离子型CM-β-CD与阳离子型多沙唑嗪对映体之间存在离子或离子对相互作用。采用中心复合设计优化关键色谱参数：pH值、甲醇（v/v）和CM-β-CD浓度。使用凯泽峰分离指数Pi作为响应函数。将这种手性分离的预测响应与实验观察结果进行了比较，并评估了四维响应面样品在显示稳健性方面的价值。
