Nowak Paweł, Olechowska Paulina, Mitoraj Mariusz, Woźniakiewicz Michał, Kościelniak Paweł
Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Ingardena St. 3, Kraków 30-060, Poland.
Jagiellonian University in Kraków, Faculty of Chemistry, Department of Theoretical Chemistry, Ingardena St. 3, Kraków 30-060, Poland.
J Pharm Biomed Anal. 2015 Aug 10;112:89-97. doi: 10.1016/j.jpba.2015.04.027. Epub 2015 Apr 24.
In this work the acid dissociation constants--pKa of warfarin and its all important oxidative metabolites have been determined by capillary electrophoresis-based methods. It has resulted in a complete description of two acid-base dissociation equilibria, yet not investigated experimentally for phase I metabolites of warfarin. The capillary electrophoresis (CE) method based on the relation between effective electrophoretic mobilities and pH has proven to be a suitable tool for pKa determination, while the spectrophotometric (CE-DAD) and the internal standard methods (IS-CE), have appeared to be promising alternative approaches. The CE-DAD approach based on the change in absorbance spectra between the acidic and basic forms is a combination between capillary electrophoresis and spectrophotometric titration, and yields very consistent values of pKa1 with CE. The IS-CE, in turn, enables an estimation of pKa1 and pKa2 from only two analytical runs, however, less accurate than CE and CE-DAD. The Debye-Hückel model has been confirmed experimentally as a good predictor of pKa values at various ionic strengths. Therefore, it has been used in determination of thermodynamic pKa1 and pKa2, referring to the zero ionic strength. The results are important from the analytical, pharmacological, and theoretical points of view.
在本研究中，采用基于毛细管电泳的方法测定了华法林及其所有重要氧化代谢物的酸解离常数——pKa。这一研究完整地描述了两种酸碱解离平衡，但尚未对华法林的I相代谢物进行实验研究。基于有效电泳迁移率与pH值之间关系的毛细管电泳（CE）方法已被证明是一种适用于测定pKa的工具，而分光光度法（CE-DAD）和内标法（IS-CE）则是颇具前景的替代方法。基于酸性和碱性形式吸光度光谱变化的CE-DAD方法是毛细管电泳与分光光度滴定的结合，其所得pKa1值与CE法非常一致。反过来，IS-CE仅通过两次分析运行就能估算pKa1和pKa2，然而，其准确性不如CE法和CE-DAD法。德拜-休克尔模型已通过实验证实是不同离子强度下pKa值的良好预测模型。因此，它被用于测定指零离子强度的热力学pKa1和pKa2。从分析、药理和理论角度来看，这些结果都很重要。
