A New Sensitive Fluorirnetric Method for the Determination of Heptaminol and Mexiletine in Pharmaceuticals

An accurate and very sensitive spectrofluorimetric method is proposed for the estimation of heptaminol (HP) and mexiletine (MX) in their pure forms and in pharlnaceutical formulations. The method is based on the reaction of these drugs with the strong fluorigenic reagent [9,1O-Dimethoxy-2-anthracenesulfonic acid sodium salt (DAS)] at pH (2.5). The formed complexes are extracted into chloroform and measured spectrofluori~netrically. The maximum wavelengths of excitation and emission spectra of heptaminol complex are 381 and 441 m, respectively. While those of mexiletine complex are 385 and 450 nrn, respectively. Heptaminol can be determined in the concentration range of 0.016-0.144 µg ml⁻¹ and that of mexiletine in the range of 0.024-0.176 µg ml⁻¹, when extracted from the solutions into chloroform. Different parameters affecting the reaction conditions were thoroughly studied. No interference was observed in the presence of common pharmaceutical excipients. The proposed method has been successfully applied to the analysis of commercial pharmaceutical fonnulations and the results have been statistically compared with those obtained by the reference methods.