Utility of Certain Π Acceptors for Spectrophotometric Determination of Sildenafil Citrate

Sildenafil citrate was determined through charge transfer complexes (CTC) formation with three electron acceptor reagents. The methods involve the reaction of Sildenafil citrate as n-donor with either Chloranil (tetrachloro 1,4-benzoquinone), tetracyanoethylene (TCNE) or 7,7,8,8-tetracyanoquinodimethane (TCNQ) as n-acceptors, to give a stable and highly colored radical anion. The colored products were quantified spectrophotometrically. The condition ranges adhering to Beer's law are 0.05-3.00 mg/ml. The molar ratios of the reactants were ascertained. The different parameters were carefully studied and optimized. Statistical analysis of the results revealed equal precision and accuracy to the results of the reported method. The methods were applied for determination of sildenafil citrate in pure form and in Viagra tablets.