Spectrophotometric determination of carbinoxamine maleate in pharmaceutical formulations by ternary complex formation with Cu(II) and eosin

A simple and sensitive spectrophotometric method was developed for the determination of carbinoxamine maleate in pharmaceutical formulations. The method is based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin, and carbinoxamine maleate. The absorption spectra of the ternary complexes shows, under optimum conditions, a maxima at 538 nm, with apparent molar absorptive 6.1690 × 104 mol−1 cm−1, Sandell’s sensitives 6.75 × 10−3 μg cm−2, and linearity in the concentration range 0.75–10.0 μg ml−1. The method can be achieved with high accuracy (recovery values, 100 ± 2%) and precision (with standard deviation 0.029–0.155 and relative standard deviation 3.87–1.55%). The method was again successfully applied, with high accuracy and good precision, for the determination of carbinoxamine maleate in various pharmaceutical formulations (syrup, drops, and tablets).