Polarographic behaviour and determination of ranitidine in pharmaceutical formulations and urine

A polarographic method for the determination of ranitidine is described, based on the reduction of the nitro group at a dropping-mercury electrode. The proposed method permits the drug to be determined, without any prior separation or extraction, in pharmaceutical formulations and urine at levels at which the unchanged drug is excreted. The current is diffusion controlled and proportional to concentration from 3.58 x 10(-3) to 1.50 mmol l-1. The detection limit is 1.07 x 10(-3) mmol l-1. The reduction process was studied at different pH values and a reduction mechanism is proposed in which the importance of the homogeneous chemical reactions associated with the electron-transfer steps are indicated.