Thormann Wolfgang, Caslavska Jitka, Mosher Richard A
Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland.
Electrophoresis. 2015 Mar;36(5):773-83. doi: 10.1002/elps.201400457. Epub 2015 Jan 29.
A computer simulation study describing the electrophoretic separation and migration of methadone enantiomers in presence of free and immobilized (2-hydroxypropyl)-β-CD is presented. The 1:1 interaction of methadone with the neutral CD was simulated by using experimentally determined mobilities and complexation constants for the complexes in a low-pH BGE comprising phosphoric acid and KOH. The use of complex mobilities represents free solution conditions with the chiral selector being a buffer additive, whereas complex mobilities set to zero provide data that mimic migration and separation with the chiral selector being immobilized, that is CEC conditions in absence of unspecific interaction between analytes and the chiral stationary phase. Simulation data reveal that separations are quicker, electrophoretic displacement rates are reduced, and sensitivity is enhanced in CEC with on-column detection in comparison to free solution conditions. Simulation is used to study electrophoretic analyte behavior at the interface between sample and the CEC column with the chiral selector (analyte stacking) and at the rear end when analytes leave the environment with complexation (analyte destacking). The latter aspect is relevant for off-column analyte detection in CEC and is described here for the first time via the dynamics of migrating analyte zones. Simulation provides insight into means to counteract analyte dilution at the column end via use of a BGE with higher conductivity. Furthermore, the impact of EOF on analyte migration, separation, and detection for configurations with the selector zone being displaced or remaining immobilized under buffer flow is simulated. In all cases, the data reveal that detection should occur within or immediately after the selector zone.
本文介绍了一项计算机模拟研究，该研究描述了在游离和固定化（2-羟丙基）-β-环糊精存在下美沙酮对映体的电泳分离和迁移情况。通过使用在包含磷酸和氢氧化钾的低pH背景电解质中实验测定的配合物迁移率和络合常数，模拟了美沙酮与中性环糊精的1:1相互作用。使用配合物迁移率代表手性选择剂作为缓冲添加剂的自由溶液条件，而将配合物迁移率设为零则提供了模拟迁移和分离的数据，此时手性选择剂是固定化的，即不存在分析物与手性固定相之间非特异性相互作用的毛细管电色谱（CEC）条件。模拟数据表明，与自由溶液条件相比，在CEC中采用柱上检测时，分离更快，电泳位移速率降低，灵敏度提高。模拟用于研究样品与CEC柱界面处手性选择剂存在时（分析物堆积）以及分析物通过络合离开环境时（分析物解堆积）的电泳分析物行为。后一个方面与CEC中的柱外分析物检测相关，本文首次通过迁移分析物区带的动力学进行了描述。模拟提供了通过使用具有更高电导率的背景电解质来抵消柱端分析物稀释的方法。此外，还模拟了在缓冲液流动下选择剂区带被置换或保持固定的配置中电渗流对分析物迁移、分离和检测的影响。在所有情况下，数据都表明检测应在选择剂区内或之后立即进行。
