Polymer membrane sensors for sildenafil citrate (Viagra) determination in pharmaceutical preparations

Abstract

The construction and performance characteristics of ion selective membrane electrodes for sildenafil citrate (SC) drug (the active component of Viagra) are described. The proposed sensors are based on the formation of the complex ion associates of SC with sodium tetraphenylborate (SC–TPB) and phosphomolybdic acid (SC–PMA) as ionophores in poly vinyl chloride membrane (PVC). Both electrodes SC–PMA and SC–TPB showed a linear and stable potential response with near-Nernstian slope of 55.5±0.35 and 53.5±0.3 mV per decade over a wide range of concentration 10 −2 to 10 −5 M sildenafil with good reproducibility, respectively. The electrodes showed a fast response time of 30 and 40 s. and were used over a wide range of pH 3–6. The selectivity coefficients indicated good selectivity for SC drug over a large number of nitrogenous compounds and some inorganic cations. The proposed sensors are tested for the analysis of SC in pure form, pharmaceutical preparations and blood serum. An average recovery of 98.9–99.5±0.6% and correlation to the existing methods of 0.998 were achieved.