Spectrofluorimetric and high performance liquid chromatographic methods have been developed for the accurate
and sensitive determination of Aspirin in mixture with Dipyridamole and in presence of its degradation product (Salicylic
acid). The spectrofluorimetric method was based on the use of the first and second derivatives of the ratio of the
emission spectra with a zero-crossing technique. The ratio spectra were obtained by dividing the emission spectrum of the
ternary mixture by that of one of the components. The other components were quantified from their respective calibration
graphs treated similarly. The proposed RP-HPLC method utilized an Adsorbosil C8, 10 m, 250mmx4.6mm i.d. column,
at ambient temperature, optimum mobile phase consisted of water-acetonitrile-ortho-phosphoric acid (65:35:2 v/v/v), with
flow rate monitored at 1.5 ml/min, and UV detection at 250 nm. The total chromatographic time per sample was about 6
min with dipyridamole, aspirin and salicylic acid eluting at retention times 2.2, 3.8 and 4.6 min, respectively. Evaluation
of linearity, accuracy, precision, selectivity and sensitivity of the methods produced satisfactory results.
The objective of this work was to introduce new analytical methods for this ternary mixture, as the literature reveals only
one method of analysis. The proposed methods were able to quantify Aspirin, Dipyridamole and Salicylic acid, irrespective
of the percentage of the latter in sample; and have been successfully applied to the commercial pharmaceutical formulations
without any interference of excipients.