The present study describes analytical method of 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H–pyrazolo[4,3-d]pyrimidin-5-yl)-4- ethoxyphenyl]sulphonyl]-4methypiperazine citrate (sildenafil Citrate). The following specification particularly describes and ascertains the nature of this invention, and the manner in which it is to be performed. Sildenafil is an oral drug used primarily to treat male sexual function problems (impotence or erectile dysfunction) since becoming available in 199...