In this paper, a rapid and sensitive modified electrode for the determination of hydroquinone (HQ) is proposed. In this study, active compound HQ was determined from commercial drug form based on electrochemical oxidation properties at various electrodes by voltammetric methods. Electrodes modified by the electrodeposition of conducting organic polymers such as poly(3-methylthiophene, PMT), polypyrrole (PPY) and polyaniline (PAN) were used as chemical sensors for voltammetric analysis and flow injection detection of HQ. The electrochemical behavior of HQ at conducting polymer electrodes was compared and the effects on behavior of electrolyte type and its pH and the film thickness were systematically examined. The results showed that the proposed modified surface catalyzes the oxidation of HQ. Electrocatalytic efficiency decreases in order of PMT > PPY > PAN. Voltammetric peak positions were affected by the nature of the electrolyte and its pH. Also, the effect of increasing film thickness was to observe increased peak heights for oxidation potential of HQ. The best results for the determination of HQ were obtained by DPV in Na2SO4 (pH 2.0) and PMT electrodes. Polymer coated electrodes were also used in an amperometric detector for flow injection analysis of HQ. The responses of the polymer electrode were 5–15 times larger as compared to those of bare platinum. PMT showed improved performance as an amperometric detector for flow injection analysis systems over other types of polymer electrodes. Detection limits as low as 1 × 10–9 M were achieved using the PMT, compared to 1 × 10–6 M using platinum electrodes.
In the present work, we have developed a sensitive platform for the selective determination of Hg(II) ions based on reduced graphene oxide (rGO) electrode modified with poly cysteine (Poly-Cys). The Poly-Cys/rGO modified electrode was characterised by SEM, ATR-IR and its electrochemical behaviour was investigated through cyclic voltammetry and square wave voltammetry. The synergistic effect of rGO and poly-cysteine favoured the complexation of Hg(II) ions onto the surface of the modified electrode. The ions were then anodically stripped and the corresponding voltammograms recorded. The process of complexation followed by stripping was repeated with increasing concentrations of the metal ion. The linear range for the electrochemical determination of Hg(II) using the modified electrode was found to be from 0.05 to 2.7 μM with a detection limit of 0.006 μM. In addition, the electrode also exhibited good stability with negligible sensitivity towards interfering metal ions. The analytical applicability of the modified electrode was investigated by carrying out mercury determination in water samples obtained from various sources.
In this paper sensitivity of a multilayer graphene nanoribbon (MGNR) interconnects parameters investigated. System sensitivity was studied on parameters like length and width in stable condition. The obtained results show with increasing width and length sensitivity will decrease and increase respectively. Impulse response diagram results show with increasing 50% width sensitivity will be zero but with increasing 50% length amplitude will decrease and the time of setting will increase. On the other hand from step response of transfer function, both width and length increase cause more stability for a system but the width parameter will be better choices for manipulating the dimension of MLGNR to reach the stable system.
Fexofenadine has been assayed by two methods. Titration (given as Method A) and spectrophotometric (given as Method B) were two methods involved in the assay procedure. The proposed titrimetric technique depends on the oxidation of FFH with identified abundance of KMnO4 and uninvolved KMnO4 was dictated by reacting it with FAS whose molarity is 0.05 M. Response stoichiometry is observed to be 1:2 (FFH: potassium permanganate).
In this work, a new voltammetric biosensor, based on the encapsulation of laccase from Trametes versicolor in an electrodeposited nanocomposite film, was developed for the detection of catechol. The nanocomposite was composed of chitosan (CS) modified with trymiristine (Tr), both of natural origin, to enhance its conductivity. FTIR and SEM studies were performed to characterize the modified chitosan film and the encapsulation of the enzyme. The analytical performance of the elaborated biosensor was determined through voltammetry detection of the produced quinone. Catechol was detected in a linear range between 10–20 and 10–15 M and a sensitivity of 0.4667 mA/p [catechol] was found. The repeatability of this biosensor is good as its RSD is equal to 1.35% and it shows stability for four weeks. To test the functionality of the developed biosensor, the total phenolic content of three samples of natural oils was determined and compared to a colorimetric test.
