Spectrophotometric Determination of Salbutamol Sulphate and Mefenamic Acid Using Azur-A Dye in Presence of Oxidizing Agent N-bromosuccinimide

A simple, accurate and sensitive indirect spectrophotometric method has been developed for the determination of salbutamol sulphate and mefenamic acid in pure forms and in pharmaceutical preparations (capsule, syrup, tablet). This method based on the bromination of the drug with N-bromosuccinimide in acidic medium and the unreacted oxidizing agent react with constant amount of Azur-A dye solution due to bleach their colour and measured the absorbance of the residual colour dye at 606.5 nm.The molar absorptivity for salbutamol sulphate and mefenamic acid are 2.3 × 104 L.mol-1.cm-1 and 8.1× 103 L.mol-1.cm-1 respectively. Beer's Law was obeyed over the concentration range of 1.6 -12.8 µg/ml for salbutamol sulphate and1.6 -13.6 µg/ml for mefenamic acid. The limit of detection (LOD) were 0.0367µg/ml and limit of quantitation (LOQ) were 0.1226 µg/ml for both drugs. In addition, the recovery levels of the drugs were in the range 100.56% and 100.74%. The method was created to be simple, cost-effective and rapid because it does not involve any solvent extraction. The developed method was successfully applied for the determination of the studied drugs.