One titrimetric and two spectrophotometric methods are described for the determination of ketotifen fumarate (KTF) in bulk drug and in tablets using cerium(IV) as the oxidimetric agent. In titrimetry (method A), the drug was treated with a measured excess of cerium(IV) in H2SO4 medium and after a standing time of 10 min, the surplus oxidant was determined by back titration with iron(II). The spectrophotometric procedures involve addition of a known excess of cerium(IV) to KTF in acid medium followed by the determination of unreacted oxidant by reacting with either p-dimethyl amino benzaldehyde and measuring the resulting colour at 460 nm (method B) or o-dianisidine and subsequent measurement of the absorbance of coloured product at 470 nm (method C). Titrimetric assay is based on a 1 : 2 reaction stoichiometry between KTF and cerium(IV) and the method is applicable over 2–18 mg range. In spectrophotometry, regression analysis of Beer's law plots showed a good correlation in 0.4–8.0 and 0.4–10.0 g mL−1 KTF ranges for method B and method C, respectively, and the corresponding molar absorptivity coefficients are calculated to be 4.0 × 104 and 3.7 × 104 L mol−1 cm−1.
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机译：描述了一种滴定法和两种分光光度法，使用铈（IV）作为氧化剂测定散装药物和片剂中的富马酸酮替芬（KTF）。在滴定法（方法A）中，在H2SO4介质中用测得的过量铈（IV）处理药物，静置10分钟后，通过用铁（II）反滴定法测定过剩的氧化剂。分光光度法包括在酸性介质中向KTF中添加已知过量的铈（IV），然后通过与对二甲基氨基苯甲醛反应并在460nm处测量所得颜色（方法B）或邻苯二甲醛来测定未反应的氧化剂。苯并二氢吡啶和随后在470 nm下测量有色产物的吸光度（方法C）。滴定分析基于KTF与铈（IV）之间的1 :: 2反应化学计量，该方法适用于2-18mg范围。在分光光度法中，比尔定律图的回归分析显示方法B和方法C的KTF范围分别为0.4–8.0和0.4–10.0 g mL −1 ，并且相应的摩尔吸收系数为计算为4.0×10 4 和3.7×10 4 L mol -1 cm -1 。
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