Simultaneous determination of amlodipine besylate and valsartan using a micelle-enhanced first derivative synchronous spectrofluorimetric method and application in their co-formulated tablets

A novel, highly sensitive and simple first derivative synchronous spectrofluorimetric method was developed for simultaneous determination of the binary mixture of amlodipine besylate (AML) and valsartan (VAL) in their co-formulated tablets. The proposed method is based on the measurement of the synchronous fluorescence intensity of these drugs at Δλ = 80 in an aqueous sodium dodecyl sulphate (SDS) system. The fluorescence intensities of both AML and VAL were greatly enhanced (200% and 220% for AML and VAL respectively) in the presence of SDS. The different experimental parameters affecting the fluorescence of the two drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the ranges of 0.5–4 μg mL−1 and 0.05–3.0 μg mL−1 for VAL and AML, respectively with lower detection limits (LOD) of 0.027 and 0.022 μg mL−1 and quantification limits (LOQ) of 0.083 and 0.007 μg mL−1 for VAL and AML, respectively. The proposed method was successfully applied for the determination of the two compounds in laboratory prepared mixtures and in commercial tablets. The proposed method was successfully applied to the content uniformity testing of tablets.