A Simple Spectrophotometric Method for the Determination of Famotidine via Reaction with Alizarin Red S

A simple, quick, and sensitive spectrophotometric method was proposed to determine famotidine (FAMT) in its pure form and pharmaceutical preparation (tablet). The method involves the reaction of FAMT with alizarin red S to produce a stable, water-soluble red complex with the maximum absorption signal at 528 nm, Beer's law is followed for standard FAMT solutions in the range of 6.0-80 µg/mL with a negative deviation at concentrations higher than 80 µg/mL. The method is sensitive. The molar absorptivity and Sandell᾽s sensitivity index values are 3.3 × 10 4 l/mol.cm and 0.0109 µg /cm2 respectively. Two approaches were applied to determine the amount of FAMT in its pharmaceutical formulation (famosam tablets), the one depending on a regression equation and the second on the standard addition method. The results were obtained with sufficient precision and accuracy, with negligible effects from excipient interference.