Flow Injection Spectrophotometric System for Ranitidine Determination in Pharmaceuticals Using Cerium(IV) and Ferroin

An indirect flow injection spectrophotometric procedure for the determination of ranitidine in pharmaceutical formulations is proposed. The method was based on the oxidation of the ranitidine with cerium(IV) in acidic medium and subsequent determination of cerium(IV) excess by reaction with ferroin which was monitored spectrophotometrically at 500 nm. The linearity of the analytical curve for ranitidine ranged from 2.5 x 10-4 to 1.25 x 10-3 mol L-1. The detection limit of 1.6 x 10-6 mol L-1 and recoveries between 96.6 and 103 % were obtained. The sampling rate of 60 determinations per hour and the RSD smaller than 0.3% for 7.1 x 10-4 mol L-1 ranitidine were also obtained. The method was applied with success in the determination of ranitidine in several commercial formulations.