RP-HPLC测定汉黄芩苷、汉黄芩素和千层纸素A的pK_a

目的：采用反相高效液相色谱法测定汉黄芩苷、汉黄芩素和千层纸素A的pK_a，为该单体的剂型设计与临床应用提供重要参考。方法：基于待测成分保留因子（k）随流动相的pH变化而变化，采用乙腈-不同pH缓冲盐溶液作为流动相，依次测定汉黄芩苷、汉黄芩素和千层纸素A的k，根据pK_a和k的函数关系计算其pK_a。结果：汉黄芩苷、汉黄芩素和千层纸素A的pH-k曲线均呈现S型，pK_a分别为3.84±0.16、7.48±0.11、7.53±0.13。结论：该方法具有样品损耗少，分析速度快，重现性好，准确度高，方便简单的特点，可用于测定汉黄芩苷、汉黄芩素和千层纸素A的pK_a。

Objective: To apply the RP-HPLC method for determination of the pK_a values of wogonoside,wogonin and oroxylin-A,in order to provide the reference to the rational design of dosage forms and clinical application of the drug. Methods: Acetonitrile-different pH buffer solutions were used as the mobile phase to determinate the k values of wogonoside,wogonin and orgxylin-A on the basis of the relationship of retention factor (k) of the compound investigated and the pH value of the mobile phase.k was determined respectively for wogonoside,wogonin and orgxylin-A and the pK_a value was calculated according to the formula of pK_a and k. Results: The pH-k plot of wogonoside,wogonin and oroxylin-A was a sigmoid curve and the pK_a value was 3.84±0.16,7.48±0.11 and 7.53±0.13 respectively. Conclusion: The proposed method is low sample-consuming,with characteristics of rapid sample analysis,high sensitivity and accuracy,and convenience which could be easily used for analysis of the pK_a values of wogonoside,wogonin and oroxylin-A.