RESUMO
In this study, different derivative spectrophotometric methods are proposed for the simultaneous determination of chlorpheniramine maleate [CP], phenylephrine HCl [PE] and phenylpropanolamine HCl [PP] in their ternary mixtures and in pharmaceutical dosage forms. Spectra of single component and ternary mixtures of various concentrations and combinations from zero- to fourth-derivation were obtained. Also the spectra of the excipients including lactose, starch, and microcrystalline cellulose were obtained to study the possible interference from matrices. Zero-crossing derivative spectrophotometry based on recording the second-derivative curve for PE at 286.5 nm and fourth-derivative curve for PP at 220 nm were used for determining each component. Third component, CP, was determined by measuring absolute amplitudes at 265.8, 262.2, 269.5, and 273.8 nm in its second derivative spectra. Results showed that the matrices have no interferences. The calibration curves were linear in the range of 1-8 micro g/ml for PE; 5-30 micro g/ml for PP; and 2-8 micro g/ml for CP. The limits of detection were 0.2 micro g/ml for PE, 0.1 micro g/ml for PP, and 0.3 micro g/ml for CP. The mean percentage recoveries obtained for different synthetic mixtures by using this method were 95.3% with coefficient of variation of 4.3% for PE, 101.5% with coefficient of variation of 1.4% for PP, and 99.4% with coefficient of variation of 1.5% for CP. This method has been applied successfully for the determination of PE and PP in its combination with CP in Antihistamine Decongestant tablets with a high percentage of recovery, good accuracy and precision