Development and validation of indirect visible spectrophotometric methods for oxcarbazepine in pure and the tablet dosage form

Abstract

Three simple, accurate and highly sensitive indirect spectrophotometric methods have been developed for the determination of oxcarbazepine (OXC) in both pure and in pharmaceutical preparations. The methods are based on the oxidation of oxcarbazepine by a known excess of cerium(IV) in acid medium. This was followed by the determination of unreacted cerium(IV), which oxidizes leuco dyes to colored dyes in the same acid medium. In method A, an unreacted cerium(IV) oxidizes leuco crystal violet to crystal violet dye which is measured at 580nm. A bluish-colored malachite green with a maximum absorption at 610nm is developed in method B. In method C, cerium(IV) oxidizes leuco xylene cyanol FF to blue colored xylene cyanol FF having absorption maximum at 610nm. In all these methods, the amount of cerium(IV) reacted corresponds to the amount of OXC and the absorbance is found to decrease linearly with OXC concentration. Beer’s law was obeyed in the concentration range of 0–2.5, 0–2.0 and 0–2.5μgml−1 for methods A, B and C, respectively, and the corresponding molar absorptivity values are 3.86×104, 4.41×104 and 2.16×104lmol−1cm−1. All variables have been optimized and the results were statistically compared with those of a literature method by employing the student’s t-test and F-test. No interference was observed from excipients normally added to the tablets.