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目的:利用库伦滴定分析技术,建立一种针对穿心莲内酯化学成分的纯度检测新方法。方法:采用穿心莲内酯与溴离子间的电荷转移量,实现利用库仑滴定检测穿心莲内酯化学成分纯度目的。以4 mol.L-1盐酸-1 mol.L-1溴化钾-1mol.L-1硝酸钾1∶1∶1为电解液,阳极上电解生成的溴与穿心莲内酯发生反应,电极反应电子转移数为2。结果:穿心莲内酯化学样品的纯度值为99.76%,RSD 0.33%。利用高效液相色谱法的面积归一化法对库伦滴定新分析方法测得的纯度值进行验证,结果为99.77%,RSD 0.02%。结论:2种测定方法结果一致,表明建立的库伦滴定法的科学,可行。该法具有快速、简便、灵敏、准确和不需要用标准物质等优点,可用于测定穿心莲内酯化学物质的纯度值。
OBJECTIVE: To establish a new method for purity determination of andrographolide by using coulometric titration technique. Methods: By using the charge transfer between andrographolide and bromide ions, the purity of the andrographolide can be detected by Coulometric titration. With 4 mol.L-1 hydrochloric acid-1 mol.L-1 potassium bromide-1 mol.L-1 potassium nitrate 1: 1: 1 as the electrolyte, the anode electrolysis generated by bromine and andrographolide reaction, electrode reaction The electron transfer number is 2. Results: The purity of andrographolide was 99.76% and the RSD was 0.33%. The area normalization method of HPLC was used to verify the purity value of the new analytical method of coulometric titration, with a result of 99.77% and a RSD of 0.02%. Conclusion: The results of the two methods are consistent, indicating that the established coulometric titration method is scientific and feasible. The method is fast, simple, sensitive, accurate and does not require the use of standard substances, etc., can be used to determine the purity of andrographolide chemicals.