Simultaneous determination of aspirin and isosorbide 5-mononitrate in formulation by reversed phase high pressure liquid chromatography.

A simple, precise and rapid reversed phase HPLC method was developed for the simultaneous estimation of aspirin (AS) and isosorbide 5-mononitrate (ISM) in combined formulation. The method was carried out on a Thermo Quest C18 column using a mixture of water:methanol (water pH adjusted to 3.4 using dilute orthophosphoric acid) and detection was carried out at 215 nm using chlorzoxazone as internal standard. Both the drugs showed linearity in the range of 2-10 microg/ml and limits of quantification was found to be 4 and 40 ng/ml for AS and ISM, respectively.