Sensor For Determination Of Ascorbic Acid Research Articles

Electrocatalytic simultaneous determination of ascorbic acid, uric acid and l–Cysteine in real samples using quercetin silver nanoparticles–graphene nanosheets modified glassy carbon electrode

By immobilizing of quercetin at the surface of a glassy carbon electrode modified with silver nanoparticles and graphene nanosheets (Q–AgNPs–GNs–GCE) a new sensor has been fabricated. The cyclic voltammogram of Q–AgNPs–GNs–GCE shows a stable redox couple with surface confined characteristics. Q–AgNPs–GNs–GCE demonstrated a high catalytic activity for l–Cysteine (l–Cys) oxidation. Results indicated that l–Cys peak potential at Q–AgNPs–GNs–GCE shifted to less positive values compared to GNs–GCE or AgNPs–GCE. Also, the kinetic parameters such as the electron transfer coefficient,, and the heterogeneous electron transfer rate constant, k′, for the oxidation of l–Cys at the Q–AgNPs–GNs–GCE surface were estimated. In differential pulse voltammetric determination, the detection limit of l–Cys was obtained 0.28μM, and the calibration plots were linear within two ranges of 0.9–12.4μM and 12.4–538.5μM of l–Cys. Also, the proposed modified electrode is used for the simultaneous determinations of ascorbic acid (AA), uric acid (UA), and l–Cys. Finally, this study has demonstrated the practical analytical utility of the sensor for determination of AA in vitamin C tablet, l–Cys in a milk sample and UA in a human urine sample.

An Electrochemical Nanosensor for Simultaneous Voltammetric Determination of Ascorbic Acid and Sudan I in Food Samples

In this work, we describe application of a high-sensitive electrochemical sensor for determination of ascorbic acid (AA) in the presence of high concentration of Sudan I in food samples. In the first step, we study synthesis and characterization of NiO/NPs with X-ray diffraction (XRD) method. In the second step, application of NiO/NPs describe in the preparation of carbon-paste electrode modified with (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-4-ethylbenzene-1,2-diol (DEDED) as a high-sensitive and selective voltammetric sensor for determination of AA and Sudan I. The electrocatalytic oxidation of AA at the modified electrode was investigated by cyclic voltammetry, chronoamperometry and square wave voltammetry (SWV). For the mixture containing AA and Sudan I, the peaks potential was well separated from each other. Their square wave voltammetrics peaks current increased linearly with their concentration at the ranges of 0.01–600 and 0.5–1,000 μM, with the detection limits of 0.006 and 0.2 μM, respectively. Finally, the proposed method was also examined as a selective, simple, and precise electrochemical sensor for the determination of AA and Sudan I in real samples such as fruit juices, fresh vegetable juice, chilli sauce and tomato sauce.