Characterization of Mn-nanoparticles decorated organo-functionalized SiO2–Al2O3 mixed-oxide as a novel electrochemical sensor: application for the voltammetric determination of captopril

Abstract

In this work a new sensor in nano size containing Mn–nanoparticles decorated organo-functionalized nanosized SiO₂–Al₂O₃ mixed-oxide support was developed as a new electrocatalysis for oxidation of organic compounds such as captopril. SiO₂–Al₂O₃ mixed–oxide were functionalized with Schiff base ligand and thereatfer, in the next step, Mn–nanoparticles were prepared over the organo–functionalized SiO₂–Al₂O₃ mixed–oxide. The synthesized materials were characterized with different methods such as FT–IR spectroscopy, UV–vis, CHN elemental analysis, TEM, ICP–OES, cyclic voltammetry, and electrochemical impedance spectroscopy. Under the optimum conditions (pH 7.0) in cyclic voltammetry, the oxidation of the captopril was occurred at a potential about 650 mV at a surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.30–5.0 and 5.0–340 μmol L⁻¹captopril. The detection limit was found to be 0.095 μmol L⁻¹captopril. The kinetic parameters such as electron transfer coefficient and catalytic reaction rate constant were also determined. Finally, the modified electrode used as a novel electrochemical sensor for the determination of captopril in real samples such as pharmaceutical, patient and safe human urine.