Spectrophotometric Determination of Catecholamine Containing Drugs Using Calcon Dye

Calcon dye has been used for spectrophotometric determination of catecholamine-containing drugs, namely, adrenaline, methyldopa and dopamine in their pure forms and pharmaceutical formulations. The method is based on the oxidation of the above drugs with an excess of Nbromosuccinimide (NBS) in an acidic medium. The residual oxidizing agent bleaches the blackish-brown color of calcon measured at 510 nm. The decolorization of the dye is proportional to the residual amount of NBS, which is proportional to the concentration of the drug. Linear calibration graphs were obtained in the concentration range 0.5-16.0, 2.0-40.0 and 1.036.0 μgmL -1 with molar absorptivity values 1.10×104 , 3.2×103 and 4.3×103 Lmol-1 cm-1 for above drugs, respectively. The method is simple, sensitive, accurate, precise and free from excipients. The developed method was successfully applied to determine the drugs in their pharmaceutical formulations.