Application of Cerium (IV) as an Oxidimetric Agent for the Determination of Ethionamide in Pharmaceutical Formulations

Abstract

Two simple methods are described for the determination of ethionamide (ETM) in bulk drug and tablets using cerium (IV) sulphate as the oxidimetric agent. In both methods, the sample solution is treated with a measured excess of cerium (IV) solution in H2SO4 medium, and after a fixed standing time, the residual oxidant is determined either by back titration with standard iron (II) solution to a ferroin end point in titrimetry or by reacting with o-dianisidine followed by measurement of the absorbance of the orange-red coloured product at 470 nm in spectrophotometry. In titrimetry, the reaction proceeded with a stoichiometry of 1 : 2 (ETM : Ce (IV)) and the amount of cerium (IV) consumed by ETM was related to the latter's amount, and the method was applicable over 1.0–8.0 mg of drug. In spectrophotometry, Beer's law was obeyed over the concentration range of 0.5–5.0 μg/mL ETM with a molar absorptivity value of 2.66 × 104 L/(mol·cm). The limits of detection (LOD) and quantification (LOQ) calculated according to ICH guidelines were 0.013 and 0.043 μg/mL, respectively. The proposed titrimetric and spectrophotometric methods were found to yield reliable results when applied to bulk drug and tablets analysis, and hence they can be applied in quality control laboratories.

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“…Reagent Perchloric acid 15,16 has been as an oxidant for the determination of lansoprazole in pharmaceutical capsules and isoniazid. Similarly in another experiment, Potassium iodate 17 and Cerium (IV) 18 was employed as an oxidant for estimation of ethionamide in pharmaceutical formulations. Oxidant diperiodatocuprate (III) 19 in an aqueous alkaline medium, has been used to oxidize aspartame.…”

Graphene oxide-based electrochemical activation of ethionamide towards enhanced biological activity

“…8 Considering the above mentioned side effects, researchers have developed various analytical tools for the determination and quantication of ETO from various formulations and even real samples. [9][10][11][12][13][14][15] For example, Sujitkumar et al reported a UV-Vis spectrophotometric method for ETO estimation from bulk and tablets. 10 Madni et al gave an account of an HPLC method for the determination of ETO from serum.…”

“…11 Moreover, the spectrometric estimation of ETO was carried out using Folin-Ciocalteu reagent with iron(III)-ferricyanide as the chromogenic agent complexing with ETO. 13 Volumetric determination of ETO in pharmaceutical formulations was carried out by using cerium(IV) as the oxidimetric agent. 14 These aforementioned methods had certain limitations, such as volumetric constraint, low sensitivity, usage of toxic chemicals, HPLC based methods requiring ltration and degassing, labor-intensiveness, and need of expertise for handling, longer process time and high cost of reagents.…”