Departament de Química Analítica, Universitat de Barcelona, Barcelona, Spain.
J Chromatogr A. 2011 Jun 24;1218(25):3928-34. doi: 10.1016/j.chroma.2011.04.054. Epub 2011 Apr 27.
A set of 25 monoprotic bases is proposed as internal standards for pK(a) determination by capillary electrophoresis. The pK(a) of the bases is determined and compared with available literature data. The capillary electrophoresis internal standard method offers numerous advantages over other typical methods for pK(a) determination, especially of analysis time and buffer preparation. However, it requires disposing of appropriate standards with reference pK(a) value. The set of bases established in this work together with the set of acids previously established provide a reference set of compounds with well-determined acidity constants that facilitate the process of selecting appropriate internal standards for fast pK(a) determination by capillary electrophoresis in high throughput screening of pharmaceutical drugs. In addition, the performance of the method when acidic internal standards are used for the determination of acidity constants of basic internal standards has also been tested. Although higher errors may be expected in this case, good agreement is observed between determined and literature values. These results indicate that in most cases structural similarity between the analyte and the internal standard might not be an essential requirement in the internal standard method.
提出了一组 25 种一元碱基作为毛细管电泳法测定 pK(a)的内标。测定了碱基的 pK(a)值，并与现有文献数据进行了比较。与其他典型的 pK(a)测定方法相比，毛细管电泳内标法具有许多优点，特别是在分析时间和缓冲液制备方面。然而，它需要处理具有参考 pK(a)值的适当标准品。本工作中建立的碱基组与先前建立的酸组一起提供了一组具有良好确定酸度常数的化合物，这有助于在药物高通量筛选中通过毛细管电泳快速测定 pK(a)时选择合适的内标。此外，还测试了使用酸性内标测定碱性内标酸度常数时该方法的性能。虽然在这种情况下可能会出现更高的误差，但观察到测定值与文献值之间具有良好的一致性。这些结果表明，在大多数情况下，分析物和内标之间的结构相似性可能不是内标法的必要要求。
