Spectrophotometric determination of dipyridamole and chlorpheniramine maleate using some chromotropic acid azo dyes

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of Dipyridamole using p-chlorophenylazo chromotropic acid (p-Cl) and 2-(p-nitrophenylazo)-chromotropic acid (C2B) and Chlorpheniramine maleate using p-chlorophenylazo chromotropic acid (p-Cl), p-iodophenylazo chromotropic acid (p-I), 2-(p-nitrophenylazo)-chromotropic acid (C2B) and 2-(phenylazo)-chromotropic acid (C2R). The method consists of extracting the ion-associates into methylene chloride. The ion-associates exhibit absorption maxima at 544 and 524 nm for p-Cl and C2B with Dipyridamole, and at 540, 524, 536 and 524nm for p-Cl, p-I, C2B and C2R with Chlorpheniramine maleate, respectively. Dipyridamole can be determined up to 3.50 and 3.78 mg ml(-1) using p-Cl and C2B. respectively, while Chlorpheniramine maleate can be determined up to 3.10, 2.36, 1.90 and 1.70 mg ml(-1) using p-Cl, p-I, C2B and C2R, respectively. The stoichiometric ratio of the ion-associates was estimated. The molar absorptivity and Sandell sensitivity of the reaction products were calculated. Statistical treatment of the results reflects that the procedure is precise, accurate and easily applied for the determination of the drugs under investigation in pure form and in their pharmaceutical preparations.