Flow injection fluorimetric method for the determination of ranitidine in pharmaceutical preparations using o-phthalaldehyde

A flow injection-fluorimetric procedure for the determination of ranitidine is proposed. The assay is based on the reaction of the drug with sodium hypochlorite, to produce a primary amine, which reacts with o-phthalaldehyde and 2-mercaptoethanol to form highly fluorescent derivatives, The calibration graph, based on peak area, is linear in the range 20-500 ng ml(-1) of ranitidine with an accuracy of 3.4%. The corresponding detection limit is 13 ng ml(-1) (3.7 pmol). The method was applied to the determination of ranitidine in pharmaceuticals. The recovery was quantitative and no interferences from excipients were observed.