Hewala I I, el-Yazbi F A, Awad A, Wahbi A M
Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Egypt.
J Clin Pharm Ther. 1992 Aug;17(4):233-9. doi: 10.1111/j.1365-2710.1992.tb01298.x.
Derivative spectrophotometry is applied to the determination of the dissociation constants (pKa) of some weakly dissociating compounds. The pKa value(s) can be calculated by measuring the amplitude of derivative maxima (D) at the selected wavelengths for the dissociated, undissociated and partially dissociated forms of the compound. A graphical technique, based on plotting the derivative spectrophotometric titration curves and interpolating pKa at D1/2 is also presented. Both methods are applied to pharmaceutical compounds with single and double dissociation constants. The results are in good agreement with the reported pKa values of the investigated compounds.
导数分光光度法用于测定某些弱解离化合物的解离常数（pKa）。通过测量化合物解离、未解离和部分解离形式在选定波长处的导数最大值（D）的幅度，可以计算出pKa值。还介绍了一种基于绘制导数分光光度滴定曲线并在D1/2处插值pKa的图形技术。这两种方法都应用于具有单解离常数和双解离常数的药物化合物。结果与所研究化合物报道的pKa值高度一致。
