Quantitative Determination of Olanzapine in Tablets with Visible Spectrophotometry using Cerium(IV)sulphate and Based on Redox and Complexation Reactions

[摘要] Three sensitive spectrophotometric methods were developed and validated for the quantification of olanzapine (OLP) in bulk drug and in tablets. The method involved treating OLP with a known excess of cerium(IV) in acid medium followed by the determination of unreacted oxidant by three reaction schemes in which cerium(IV) was reduced by an excess of iron(II), and the resulting iron(III) was complexed with thiocyanate, tiron or ferrocyanide and absorbance measured at 480 nm (method A), 640 nm (method B) or 700 nm (method C). Absorbance decreased linearly with concentration over the ranges 0.2-2.0 µg mL-1 (method A), 1.0-9.0 µg mL-1 (method B) and 0.3-3.0 µg mL-1 (method C). The calculated molar absorptivity values were 10.94 x104, 1.67 x104 and 4.52 x104 l mol-1 cm-1 for method A, method B and method C, respectively; and the corresponding limits of quantification (LOQ) were 0.02, 0.11 and 0.03 µg mL-1. Precision results, expressed by the intra-day and inter-day relative standard deviation values, were satisfactory, better than 3 %, and accuracy expressed as relative error varied from 0.75 to 2.5 %. The methods were successfully applied to the determination of OLP in tablets with mean percentage recoveries of 95.84 to 102.5% .The method validation results showed that the sensitivity and selectivity of the methods were adequate for drug monitoring in industrial quality control laboratories.

[学科分类] 分析化学

[关键词] Drotaverine hydrochloride; Aceclofenac; Absorbance Ratio Method; Simultaneous Equation Method; First Order Derivative Spectroscopy