Chemistry Department, Faculty of Science, Zagazig University, Zagazig, Egypt. ak
Spectrochim Acta A Mol Biomol Spectrosc. 2010 Mar;75(3):1138-45. doi: 10.1016/j.saa.2009.12.075. Epub 2010 Jan 6.
Three simple, accurate and sensitive methods (A-C) for the spectrophotometric assay of captopril (CPL) in bulk drug, in dosage forms and in the presence of its oxidative degradates have been described. The methods are based on the bromination of captopril with a solution of excess brominating mixture in hydrochloric acid medium. After bromination, the excess brominating mixture is followed by the estimation of surplus bromine by three different reaction schemes. In the first method (A), the determination of the residual bromine is based on its ability to bleach the indigo carmine dye and measuring the absorbance at 610 nm. Method B, involves treating the unreacted bromine with a measured excess of iron(II) and the remaining iron(II) is complexed with 1,10-phenanthroline and the increase in absorbance is measured at 510 nm. In method (C), the surplus bromine is treated with excess of iron(II) and the resulting iron(III) is complexed with thiocyanate and the absorbance is measured at 478 nm. In all the methods, the amount of bromine reacted corresponds to the drug content. The different experimental parameters affecting the development and stability of the color are carefully studied and optimized. Beer's law is valid within a concentration range of 0.4-6.0, 0.4-2.8 and 1.2-4.8 microg mL(-1) for methods A, B and C, respectively. The calculated apparent molar absorptivity was found to be 5.16x10(4), 9.95x10(4) and 1.74x10(5)L mol(-1) cm(-1), for methods A, B and C, respectively. Sandell's sensitivity, correlation coefficients, detection and quantification limits are also reported. No interference was observed from common additives found in pharmaceutical preparations. The proposed methods are successfully applied to the determination of CPL in the tablet formulations with mean recoveries of 99.94-100.11% and the results were statistically compared with those of a reference method by applying Student's t- and F-test.
三种简单、准确、灵敏的分光光度法（A-C）已被描述用于测定原料药、制剂中卡托普利（CPL）的含量，以及在其氧化降解产物存在的情况下测定 CP 的含量。这些方法基于 CP 与过量溴化混合物在盐酸介质中的溴化反应。溴化后，通过三种不同的反应方案来估计过量溴。在第一种方法（A）中，剩余溴的测定基于其使靛蓝胭脂红染料褪色的能力，并在 610nm 处测定吸光度。方法 B 涉及用过量的二价铁处理未反应的溴，剩余的二价铁与 1,10-邻菲啰啉络合，在 510nm 处测量吸光度的增加。在方法 C 中，剩余的溴与过量的二价铁反应，生成的三价铁与硫氰酸盐络合，在 478nm 处测量吸光度。在所有方法中，反应的溴量对应于药物含量。仔细研究和优化了影响显色发展和稳定性的不同实验参数。方法 A、B 和 C 的 Beer 定律分别在 0.4-6.0、0.4-2.8 和 1.2-4.8μg/mL 浓度范围内有效。方法 A、B 和 C 的表观摩尔吸光率分别为 5.16x10(4)、9.95x10(4)和 1.74x10(5)L mol(-1) cm(-1)。还报道了桑德尔的灵敏度、相关系数、检测限和定量限。在药物制剂中常见的添加剂没有干扰。该方法成功应用于片剂制剂中 CPL 的测定，平均回收率为 99.94-100.11%，并通过应用学生 t-检验和 F-检验与参考方法的结果进行了统计学比较。
