Spectrophotometric, Spectrofluorimetric and Voltammetric Analyses of Naftidrofuryl Oxalate in its Tablets

This work deals with several direct and indirect spectrophotometric, spectrofluorimetric and voltammetric analyses of the vasodilator drug: naftidrofuryl oxalate (NF). For the derivative spectrophotometric measurement, NF was determined by measuring the peak to peak amplitude of (1)D(263–299) and (2)D(282–311) or the absolute peak height of (1)D(237) and (2)D(241), while its reaction product with concentrated sulfuric acid was determined by measuring the peak to peak amplitude of (2)D(248–263) or the absolute peak height of (1)D(275). For the spectrofluorimetric measurement, native NF fluorescence was measured in Britton-Robinson buffer (pH 5) at λ(em) = 331 nm (λ(ex) = 277 nm), while the reaction product was measured in aqueous solution at λ(em) = 385 nm (λ(ex) = 258 nm). All factors affecting these analyses were studied and optimized. This work also describes a differential pulse cathodic voltammetric determination of the NF reaction product with concentrated sulfuric acid at the hanging mercury drop electrode (HMDE) where the experimental conditions affecting analysis including buffer pH, pulse amplitude and scan rate were examined and optimized. The chemical structure of the reaction product with concentrated sulfuric acid was investigated using several spectroscopic methods. All the developed procedures were validated and satisfactorily applied for the determination of NF in its pharmaceutical tablets.