RESEARCH ARTICLE Simple and Rapid Spectrophotometric Determination of Propranolol Hydrochloride as Base Form in Pharmaceutical Formulation through Charge Transfer Complexation

Two simple and selective spectrophotometric methods are described for the determination of propranolol hydrochloride (PPH) as base form (PPL) in bulk drug, and in tablets and capsules. The methods are based on the molecular charge-transfer complexation of propranolol base (PPL) with either 2,4,6-trinitrophenol (picric acid; PA) or 2,4-dinitrophenol (DNP). The yellow colored radical anions formed on dissociation, are quantitated at 425 nm (PA method) or 415 nm (DNP method). The assay conditions were optimized. Beer's law is obeyed in the concentration ranges 2.4-42.0 μg ml in PA method and 9.0-126.0 μg ml 1 in DNP method, with respective molar absorptivity values of 4.97 × 10 3 and 1.66 × 10 3 l mol -1 cm -1 . The reaction stoichiometry in both methods was evaluated by Job’s method of continuous variations and was found to be 1:1 (PPL:PA, PPL:DNP). The developed methods were successfully applied to the determination of PPL in pure form and commercial tablets/capsules with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and F-ratio at 95% confidence level and the results showed no significant difference between the reference and proposed methods with regard to accuracy and precision. Further, the accuracy and reliability of the methods were confirmed by recovery studies via standard addition technique.