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.