Disposable Printed Sensors Based on Carbon Black/Carbon Dots Conductive Ink for Sensitive Voltammetric Determination of Kopexil (Aminexil) in Lotion Samples

Abstract

Herein, a disposable screen-printed sensor enriched with a blend of carbon black (CB)/carbon dots (CDs) was fabricated for a novel precise differential pulse voltammetric determination of kopexil (KOP) in topical lotion samples and spiked plasma. The fabricated sensors were fully characterized, and the formulation of the homemade printing ink matrix was optimized. Modification of the electrode matrix with the carbonaceous nanoparticles improved their voltammetric response against oxidation of the KOP molecule at 1.17 V in BR buffer, pH 5 following diffusion-controlled reaction mechanism. Based on the theoretical molecular orbital calculations and electroanalytical studies, oxidation of KOP molecule may undergoes through oxidation of the terminal nitrogen atom (N8) with the transfer of two protons/electrons in the electrode reaction. At the optimized measuring conditions, the reported calibration graphs showed linear dynamic range within the KOP concentration ranged from 0.080 to 2.633 μg ml−1, and a limit of detection of 26.0 ng ml−1. Prolonged operational lifetime with high measurement reproducibility was reported for the fabricated sensors. With improved sensitivity and selectivity toward KOP, the CB/CDs based sensor were validated as a green analytical method for KOP assaying in lotion and spiked plasma samples with enhanced sensitivity compared with the chromatographic and spectrophotometric techniques.