The Use of Charge Transfer Reaction for the Spectrophotometric Estimation of Nimodipine in the bulk, Pharmaceutical Formulation and Biological Fluids

Abstract

The present study deals with a sensitive, accurate and simple spectrophotometric approach for the valuation of nimodipine in the bulk , tablet and biological fluids. The procedure involved the reaction of the reduced nimodipine with 2,3-dichloro-5,6-dicyanobenzoquinone in borate buffer solution of pH9  to form a colored yellow-orange charge transfer complex. The resulting complex is soluble in water and showed a maximum absorption peak at 464 nm. All the variables which affected the conditions such as, influence of organic solvents, pH, buffer solutions, reagent concentration , reaction time and Beer׳s law limits were studied carefully and adjusted. The optimal conditions showed that the color of charge transfer complex is stable for at least 60 minutes. The standard calibration curvature was linear in the variety from 1.0-40 µg/ml with a good value of determination coefficient (R²= 0.9989). The molar absorptivity was calculated and set up to be 1.7031x10⁴ l/mol.cm. The detection limits and quantitation limits were also estimated and found to be 0.00512 and 0.01737 µg/ml, correspondingly. The approach was established by estimating of nimodipine in the pharmaceutical tablet and biological fluids. The precision (RSD) was calculated to be better than 1.556%, whereas the values of recovery percent and relative errors were in the range of 96.33% to 101.6% and -3.67% to-1.58%  respectively, without interfering from any common excipients present the samples. The nature of the resulting complex has been studied between the reduced nimodipine and 2,3-dichloro-5,6-dicyano-benzoquinone reagent and was equal to 1:1.