Highly sensitive voltammetric sensor based on catechol-derivative-multiwall carbon nanotubes for the catalytic determination of captopril in patient human urine samples

A new catechol-derivative compound, N-(3,4-dihydroxyphenethyl)-3,5-dinitrobenzamide, was synthesized and used to construct a modified-carbon nanotubes paste electrode. The electro-oxidation of captopril at the surface of the modified electrode was studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Under the optimized conditions, the differential pulse voltammetric peak current of captopril increased linearly with captopril concentration in the ranges of 6.4 × 10−8 to 3.2 × 10−48 mol L−1. The detection limit was 3.4 × 10−8 mol L−1 captopril. The diffusion coefficient and kinetic parameters (such as electron transfer coefficient and the heterogeneous rate constant) for captopril oxidation were also determined. The RSD% for 0.5 and 10.0 μmol L−1 captopril were 2.1% and 1.6%, respectively. The proposed sensor was successfully applied for the determination of captopril in human patient urine and tablet samples.

Graphical abstractIn this work, we describe a novel sensor based on catechol-derivative as a new mediator incorporated with carbon naotubes matrix for determination of captopril in urine samples.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights• Captopril is a unique antihypertensive drug as it is the only one with a thoil-group in its structure. • This gives it the ability to act as a scavenger of free radicals in living systems. • A further advantage of the pharmaceutical is its antioxidant properties. • In this study, the application of a new dopamine-derivative as a mediator for the electrocatalytic determination of captopril is investigated using differential pulse voltammetry. • The voltammetric sensor was employed for the voltammetric determination of captopril in urine samples from both patients and healthy subjects on the captopril.