Terbinafine hydrochloride is a potent antifungal drug indicated for oral and topical treatment of mycoses. A resonance Rayleigh scattering (RRS) method was developed for the determination of terbinafine hydrochloride through a feasible complexation reaction with erythrosine B. In a weakly acidic medium (acetate buffer, pH 5.0), terbinafine hydrochloride can react with erythrosine B through the electrostatic attraction and virtue of hydrophobic force to form an ion-association complex. The reaction resulted in the appearance of a new RRS peak at 369 nm. The RRS peak was increased by increasing the concentration of terbinafine hydrochloride in the linear range of 0.1–1.5 µg ml −1 . All the reaction conditions (erythrosine B concentration, buffer volume, diluting solvent and pH) were optimized. The detection limit was 0.029 µg ml −1 while the quantitation limit was 0.089 µg ml −1 . The suggested method after its validation was successfully applied for the determination of terbinafine hydrochloride in different pharmaceutical formulations (tablets and cream) with sufficient recovery.

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 = 550 nm ( = 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 577 nm following its interaction with naftidrofuryl. The methods exhibited linearity within the ranges of 0.2 1.6 μg/mL (r2= 0.999) and 0.1 1.4 μg/mL (r2= 0.9994), with LOQ values of 0.146 and 0.099 μg/mL, and LOD 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 by 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.

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Herein, a simple reduction method for decoration of reduced graphene oxide (RGO) nanosheets with AuPdPt trimetal nanoparticles was developed. The as-synthesized nanocomposite was characterized detailedly using several techniques such as SEM, TEM, FTIR, CV and EDS. The results showed that the trimetal nanoparticles are well dispersed on RGO nanosheets, preventing the serious aggregation and maintaining good electro-catalytic activity. Benefiting from synergistic effect of AuPdPt nanoparticles and RGO, the modified electrode exhibited higher and remarkable oxidation toward retigabine (REG), anti-convulsant drug, with lowered oxidation overpotential. Under the optimum conditions for electrochemical oxidation of REG, the AuPdPt NPs@RGO/GCE displayed a wide linear range of 0.1−40.0 × 10 −7 M with LOD of 0.039 × 10 −7 M if compared to LODs of bare GCE, GO/GCE and RGO/GCE with values of 1.94 × 10 −7 M, 0.32 × 10 −7 M and 0.11 × 10 −7 M, respectively. The main merits of the proposed sensor are the good stability, selectivity and reproducibility which have been successfully applied for the analysis of REG in human plasma and urine samples with good percentage recoveries. The obtained results prove that the proposed sensor could be a promising and convenient material for the construction of reliable and high performance electrochemical sensors.

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