New methods for amlodipine and valsartan native spectrofluorimetric determination, with factors optimization study.

Four native fluorescence methods were suggested for simultaneous determination of amlodipine (AML) and valsartan (VAL). These methods were based on excitation of both drugs at λ(ex) 300 nm, in one step, to give maximum emission at λ(em) 378 and 496 nm for AML and VAL, respectively. The first method, single λ(ex) method, was used without any additions. The sensitivity of this method was further increased by the addition of hydroxy propylmethyl cellulose (HPMC) surfactant, β-cyclodextrin, or ferric oxide magnetite nanoparticles, in the other three methods. Different types of surfactants, and different concentration levels of both β-cyclodextrin and ferric oxide nanoparticles, were scanned to determine the optimum conditions for enhancing the sensitivity. Some factors affecting the fluorescence intensity of both cited drugs, like the type and volume of the added solvent (to be used as a sensing agent), and pH of measurement were studied and optimized. The proposed methods could be used in determination of AML and VAL in bulk powder, their laboratory prepared mixtures and pharmaceutical formulations. The obtained results were statistically compared to each other and to that of some reported methods. The specificity of the developed methods was investigated, and the methods were validated according to ICH guidelines.