Naftidrofuryl is a vasodilator medication used for treating cerebral and peripheral
vascular diseases. In this study, two spectroscopical techniques, spectrofluorimetric
and resonance Rayleigh scattering (RRS), were utilized to quantify naftidrofuryl in its
pharmaceutical samples. The developed methodologies in this study rely on a facile
process of forming an association complex between erythrosine B reagent and naftidrofuryl
under acidic conditions. The fluorimetric assay is based on the ability of naftidrofuryl
to quench and decrease the native fluorescence intensity of the reagent
when measured at λemis: = 550nm (λexcit: = 526 nm). Under similar reaction conditions,
the RRS method relies on the observed amplification in the RRS spectrum of
the reagent at a wavelength of 577nm following its interaction with naftidrofuryl.
The methods exhibited linearity within the ranges 0.2–1.6 μg/ml (r2 = 0.999) and
0.1–1.4 μg/ml (r2 = 0.9994), with limit of quantitation values of 0.146 and
0.099 μg/ml, and limit of detection values of 0.048 and 0.032 μg/ml, for the fluorometric
and the RRS methods, respectively. Moreover, the quenching between the
dye and naftidrofuryl was studied using Stern–Volmer analysis, and the methodologies
were experimentally optimized and validated. Additionally, acceptable recoveries
were achieved when the procedures were applied to determine naftidrofuryl in pharmaceutical
samples