Spectrophotometric determination of promethazine hydrochloride using oxidative coupling reactions with sulphacetamide sodium salt

An easy, quick, and selective spectrophotometric method for determining promethazine hydrochloride (PMZH). in aqueous medium is being developed as part of the present investigation. The principle of the suggested method is rely on oxidative coupling reactions with sulphacetamide sodium salt (SAS) in an acidic medium in the existence of sodium periodate as oxidizing agent to produce a bluish-green result which has maximum level of absorption at the wavelength of 601 nm, which follows Beer’s law in the concentration range between 0.5 and 15 µg.mL-1 of promethazine hydrochloride, with correlation coefficient value of 0.9971. The molar absorptivity and Sandell’s index values were 1.32×104 L.mol-1cm-1, 0.024277 µg.cm-1, respectively. While detection limit and quantification limit values were 0.0184 and 0.06133 µg.mL-1, respectively. The proposed method was successfully applied for the determination of PMZH in its pharmaceutical preparations as tablets.