Ando H Y, Heimbach T
Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, MI 48105, USA.
J Pharm Biomed Anal. 1997 Sep;16(1):31-7. doi: 10.1016/s0731-7085(97)00084-8.
A semi-automated method to determine pKa values spectrophotometrically is described. The method uses the capabilities of a HPLC equipped with a diode array detector (DAD) as a flow injection apparatus. The advantages are low sample consumption, rapid sample throughput, high sensitivity, and precision. Experimental pKa values obtained for two model compounds, benzoic acid (approximately 4.0) and 2-aminopyridine (approximately 6.8), are consistent with literature values. Constant ionic strength was maintained for a wide pH range. Solubilized samples in non-aqueous solvents were also investigated. The weakening in pKa values, often seen when using non-aqueous solvents, was small (0.04-0.40 pH units) compared to conventional methods.
描述了一种通过分光光度法测定pKa值的半自动方法。该方法利用配备二极管阵列检测器（DAD）的高效液相色谱仪作为流动注射装置的功能。其优点是样品消耗低、样品通量高、灵敏度高和精密度高。两种模型化合物苯甲酸（约4.0）和2-氨基吡啶（约6.8）的实验pKa值与文献值一致。在很宽的pH范围内保持恒定的离子强度。还研究了在非水溶剂中溶解的样品。与传统方法相比，使用非水溶剂时常见的pKa值减弱较小（0.04 - 0.40个pH单位）。
