Four New Vanadometric Methords for the Assay of Methdilazine in Bulk Drug and in Pharmaceutical Formulations

Kanakapura Basavaiah* and Vaidyanathan Shakuntala Charan

ABSTRACT: Two titrimetric and two spectrophotometric methods, which are simple, accurate, precise and economical, are described for the determination of methdilazine hydrochloride in bulk form and in formulations. All the methods are based on the oxidation of the drug by metavanadate in acidic condition followed by measurement of unreacted oxidant or vanadium (IV) produced in the redox reaction. In one titrimetric method (A), the drug is treated with a known excess of metavanadate in sulphuric acid medium and after the redox reaction, the residual oxidant is back titrated with iron (II) ammonium sulphate using Nphenylanthranilic acid indicator. The other titrimetric method (B) is based on the titration of vanadium (IV) produced in the redox reaction with cerium (IV) sulphate using ferroin as indicator and in the presence of acetone catalyst. In one spectrophotometric method (C) the drug is treated with a known excess of metavanadate and, after the reaction is judged to be complete, the unreacted metavanadate is determined by complexing with chromotropic acid in the same sulphuric acid medium employed for the oxidation step. The other spectrophotometric method (D) relies on the determination of vanadium (IV), a product of the redox reaction, by interacting with ferriin reagent and measuring the resulting ferroin at 510 nm.The working conditions of the methods have been optimised. Optical characteristics such as Beer’s Law limits, detection and quantification limits, molar absorptivity and Sandell sensitivity values have been reported for spectrophotometric methods. The methods were successfully applied to the determination of methdilazine in tablets and syrup, and the results obtained were in agreement with the label claim. Further, the validity of the procedures were confirmed by applying the standard-addition technique.

Download PDF

Department of Chemistry, University of Mysore, Manasagangotri, Mysore – 570 006, Karnataka, INDIA.

* Corresponding author

Received 15 Mar 2002, Accepted 11 Sep 2002