Voltammetric quantitation of nitazoxanide by glassy carbon electrode

The present study reports voltammetric reduction of nitazoxanide in BrittonâRobinson (BâR) buffer by cyclic and square-wave voltammetry at glassy carbon electrode. A versatile fully validated voltammetric method for quantitative determination of nitazoxanide in pharmaceutical formulation has been proposed. A squrewave peak current was linear over the nitazoxanide concentration in the range of 20â140 µg/mL. The limit of detection (LOD) and limit of quantification (LOQ) was calculated to be 5.23 μg/mL and 17.45 μg/mL, respectively. Keywords: Nitazoxanide, Squarewave voltammetry, Glassy carbon electrode, Pharmaceutical formulatio

Graphene interface for detection of resorcinol an endocrine disruptor in solubilized ionic liquid system : electrochemical and COSMO-RS quantum studies

We report synthesis, characterization and covalent fabrication of graphene nanosheets (GR) on Au electrode. The GR nanosheets were characterized by XRD, Raman spectroscopy, FESEM and TEM techniques. The GR nanosheets were functionalized by reduction of aryldiazonium salt (Cl−N2+–Ph–COOH) to produce GR–Ph–COOH. In another step, Au electrode was modified by cysteamine (Cyst) to form Au–S–CH2–CH2–NH2 surface. Finally, GR–Ph–COOH was covalently attached to Au–S–CH2–CH2–NH2 by carbodiimide chemistry. The GR–Cyst–Au interface was used for electrochemical determination of resorcinol (RS) in ionic liquid [C4mim] [Cl] system over a concentration range from 0.3 to 45.2 μM with a detection limit (LOD) of 0.02 μM. The faster electron transfers kinetics of RS in [C4 mim] [Cl] system was attributed to synergetic effects of GR nanosheets and [C4 mim] [Cl] medium. The GR–Cyst–Au interface was successfully applied for determination of RS in Garnier hair-color cream as a real sample analysis. Computational quantum approach i.e. COSMO-RS model was also used to study trend of interactions in a ternary mixture of water, RS and [C4 mim] [Cl] system for proposed RS sensor.Published versio

Ruthenium nanoparticles embedded poly(4-aminodiphenylamine) nanocomposites based determination of guaifenesin in real samples

An efficient sensing surface is fabricated through incorporating ruthenium on electropolymerized poly-(4-aminodiphenylamine)(Padpa) film by potentiodynamic cycling of 4-aminodiphenylamine (4-adpa) in an acidic medium. The mechanism of electropolymerization comprises the conversion of protonated monomer to di-imine species and generates positively charged radical-intermediate via dimerization step. The surface morphology of deposited film on electrode surface is studied using SEM and XPS techniques. The electrocatalytic appraisal of constructed (Ru/Padpa/GCE) sensing interface is examined towards the electro-oxidation of guaifenesin (GUA) by differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) methods. The Ru/Padpa/GCE sensing interface displayed a linear response of GUA from 1.5 to 45 µg/mL with the limit of detection (LOD) of 48.8 ng/mL (S/N = 3). The obtained higher activity of Ru/Padpa/GCE is mainly attributed to its larger active surface area, faster electron transfer kinetics, and higher catalytic sites from the interface. The Ru/Padpa/GCE sensing interface is further applied for the determination of GUA in pharmaceutical (cough syrup, and human urine) samples with a recovery of 97.1–101.0 %. The diffusion coefficient of GUA (1.51 × 10-6 cm2/s) is also obtained via theoretical electrochemical method, which ensures that Ru/Padpa/GCE sensing interface can be considered as a potential candidate for clinical diagnostic analysis