A simple and selective novel spectrophotometric method has been proposed for determination of Carbachol in pure and
pharmaceutical ophthalmic preparations. The method is developed on formation of ion-pair complex between Bromophenol blue
(BPB) and Carbachol (Carb), which is blue in color. The variables which effect the complex formation were thoroughly studied and
optimized. The Beer’s and Lambert’s plots were obeyed in a concentration range of 10-100 ppm with regression co-efficient 0.9999.
The LOD and LOQ are obtained respectively 5ppm and 10ppm. The proposed method was successfully applied to the analysis of the
cited drugs in ophthalmic preparations. The Linearity, precision, specificity, robustness and ruggedness of proposed method were
evaluated as per ICH and USP guidelines.
Keywords: BPB (Bromophenol blue), Quaternary Ammonium, Ion-Pairing, Method validation