Simple, Sensitive and Eco-Friendly Methods for the Determination of Methdilazine in Tablets and Syrup Using Cerium (IV)
One titrimetric and two spectrophotometric methods, which are simple, rapid, cost-effective and eco-friendly, are described for the determination of methdilazine hydrochloride (MDH) in bulk drug, tablet and syrup formulations based on the oxidation of MDH by Cerium (Ce) (IV). In titrimetry (method A), the acidified solution of MDH is titrated directly with Ce(IV) using ferroin as indicator. The spectrophotometric methods are based on oxidation-reduction reaction involving MDH and Ce(IV), and the resulting Ce(III) is complexed with either arsenazo(III) at pH 7.8±1.0 and absorbance measured at 620 nm (method B) or chromotrope 2R at pH 2.5±0.8 and absorbance measured at 530 nm (method C). Under optimized experimental conditions, titrimetric procedure is applicable over the range of 3-15 mg of MDH, and the reaction stoichiometry is found to be 1:2 (MDH:Ce(IV)). The spectrophotometric methods are applicable over the ranges of 0.4-10.0 μg mL-1 (method B) and 0.4-12 μg mL-1 (method C). The molar absorptivities are calculated to be 3.4×104 and 2.8×104 L mol-1cm-1 for method B and method C, respectively, and the corresponding Sandell sensitivity values are 0.0096 and 0.0118 μg cm-2. The limits of detection are calculated and found to be 0.12 and 0.38 μg mL-1 for method B and method C, respectively, with corresponding limits of quantification of 0.09 and 0.71. The methods were applied to the determination of MDH in tablets and syrup, and the results were compared statistically with those of a reference method.