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Analytical utility of atomic emission spectrometry for the determination of sildenafil citrate (Viagra) in pharmaceutical formulations

Sabry Khalil, A.Y.El-Naggar

Ion-associate complexes of sildenafil citrate; Sd cit (viagra)with (Cd(II) and Zn(II)) thiocyanates, potassiumferricyanide and ammoniumreineckate are precipitated. The solubility of the solid complexes at the recommended optimum conditions of pH and ionic strength values have been studied. Saturated solutions of each ion associate at different temperatures under the optimum precipitation conditions were prepared and the metal ion contents in the supernatant were determined. The solubility products were thus calculated at different temperatures and the thermodynamic parameters ÄH, ÄG and ÄS were calculated. Anew accurate and precise method based on direct coupled plasma atomic emission spectrometry for the determination of sildenafil citrate (0.75-85.32 ìg/ml) in pure solutions and pharmaceutical preparations is given.