Simultaneous Determination of Naphazoline Hydrochloride and Chlorpheniramine Maleate by Derivative Spectrophotometry and by Densitometry

Two methods were developed for simultaneous determination of naphazoline hydrochloride and chlorpheniramine maleate in bulk drug and dosage forms (eye and nose drops). Derivative spectrophotometry was used to eliminate band overlapping during analysis of such 2-component mixtures. Naphazoline hydrochloride was determined by recording first-derivative (D 1 ) absorbance curves: at 295.5 nm, naphazoline hydrochloride exhibits a maximum D 1 absorption whereas chlorpheniramine maleate has zero D 1 absorption. Chlorpheniramine maleate was determined by scanning the second-derivative (D 2 ) absorption spectra: at 261.7 nm chlorpheniramine maleate exhibits a D 2 maximum absorption whereas naphazoline hydrochloride has negligible D 2 absorption. Linear relations between concentration and absorbance were obtained for the concentration range 20-100 g/mL for both bulk drugs. Mean recoveries were 99.96 ± 0.97 and 99.92 ± 0.62%, for naphazoline hydrochloride and chlorpheniramine maleate, respectively. The second method Involves quantitative densitometric evaluation of thin-layer chromatograms of ethanolic solutions of the drug mixtures. Separation was performed on silica gel plates (20 x 20 cm) with acetone-25% ammonium hydroxide (90 + 10, v/v) as mobile phase. R f values were 0.68 and 0.86 for naphazoline hydrochloride and chlorpheniramine maleate, respectively. Densitometric evaluation was done by recording peak areas at 280 nm for naphazoline hydrochloride and at 262 nm for chlorpheniramine maleate. Linear relationships between concentration and peak area were obtained for the concentration ranges 2-10 g/spot and 4-10 g/spot for bulk naphazoline hydrochloride and chlorpheniramine maleate, respectively. Mean recoveries were 99.99 ± 0.75 and 99.67 ± 0.73%, respectively. The presence of the preservative cetrimide did not interfere with determination of the 2 drugs or with accuracy and precision of the 2 proposed methods.