A non-extractive, simple and sensitive spectrofluorimetric method with good selectivity has been described for the determination of the proton pump inhibitors namely; Omeprazole, Esomeprazole magnesium and Pantoprazole sodium that are used for the treatment of peptic ulcer disease. The method is based on the quenching the fluorescence intensity of the eosin Y dye, as the result of the ion-pair complex formation of the studied drugs with the dye in the presence of acetate buffer solution of pH 3.5. The quenching of the eosin Y fluorescence intensity was measured spectrofluorimetrically at 540 nm after excitation at 352 nm. At the optimum reaction conditions, the quenching values of fluorescence (∆F) and concentrations were rectilinear over the concentration ranges of 0.5–13.0, 0.7-15 and 0.3-15 µg/mL for Omeprazole, Esomeprazole magnesium and Pantoprazole sodium respectively. The recovery % values were in the range 99.92-100.56% and relative standard deviation values range was0.430-2.521 for all the studied drugs. The method was applied successfully for determination of above drugs in their pharmaceutical formulations as capsule, tablet and injectables. The method was free from interferences of common excipients.

Calcon dye has been used for spectrophotometric determination of catecholamine-containing drugs, namely, adrenaline, methyldopa and dopamine in their pure forms and pharmaceutical formulations. The method is based on the oxidation of the above drugs with an excess of Nbromosuccinimide (NBS) in an acidic medium. The residual oxidizing agent bleaches the blackish-brown color of calcon measured at 510 nm. The decolorization of the dye is proportional to the residual amount of NBS, which is proportional to the concentration of the drug. Linear calibration graphs were obtained in the concentration range 0.5-16.0, 2.0-40.0 and 1.036.0 μgmL -1 with molar absorptivity values 1.10×104 , 3.2×103 and 4.3×103 Lmol-1 cm-1 for above drugs, respectively. The method is simple, sensitive, accurate, precise and free from excipients. The developed method was successfully applied to determine the drugs in their pharmaceutical formulations.