Zinc oxide nanoparticles (ZnO NPs) and p-aminobenzenesulfonic acid (p-ABSA) were used to fabricate a modified electrode, as a highly sensitive and selective voltammetric sensor, for the determination of tartrazine. A fast and easy method for the fabrication of poly p-ABSA (Pp-ABSA)/ZnO NPs-carbon paste electrode (Pp-ABSA/ZnO NPs-CPE) by cyclic voltammetry was used. By combining the benefits of Pp-ABSA, ZnO NPs, and CPE, the resulted modified electrode exhibited outstanding electrocatalytic activity in terms of tartrazine oxidation by giving much higher peak currents than those obtained for the unmodified CPE and also other constructed electrodes. The effects of various experimental parameters on the voltammetric response of tartrazine were investigated. At the optimum conditions, the sensor has a linear response in the concentration range of 0349-5.44 μM, a good detection sensitivity (2.2034 μA/μM), and a detection limit of 80 nM of tartrazine. The proposed electrode was used for the determination of tartrazine in soft drinks with satisfactory results.

In the present study, wholly of electrochemical methodology was used to acquire an inexpensive and stable graphene oxide/cobalt oxide nanocomposite on a pencil graphite electrode (PGE). At first, the graphene oxide (GO) nanosheets were directly synthesized at pencil graphite electrode as a carbon source via a potentiostatic method in sulfuric acid solution. Then, cobalt oxide nanoparticles (CoO x NPs) was loaded by cyclic voltammetry on the GO-coated PGE. The morphology of unmodified PGE, GO/PGE and CoO x NP/GO/PGE were characterized by scanning electron microscopy (SEM). The catalytic properties of the quickly designed sensor were used to appraise the electrochemical behavior of insulin. The electroactivity of insulin was significantly enhanced on the CoO x NPs/GO nanocomposite compared with unmodified electrode. A linear dynamic range between 0.46 to 100 nmol dm -3 were obtained with a detection limit of 0.12 nmol dm -3 and a superior detection sensitivity 0.687 μA/nmol dm -3 . Also, the sensor response was not damaged by the presence of common biological intruders such as ascorbic acid, uric acid, citric acid, and glucose. Eventually, three pharmaceutical insulin samples from three different brands (Regular, Isophane, and Lansolin) were selected and analyzed. The recovery percentage suggests that the proposed sensor could be utilized in routine analysis of pharmaceutical preparations.

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The origin of MAMP and its side effects have been reported. The optical and electrochemical sensors for sensing MAMP have been reviewed. The advantages and drawbacks of the applied modifiers and interfaces have been described. The undeniable role of nanotechnology in the expansion of the MAMP sensors has been described. Some offers for commercializing of MAMP sensors for the rutin analysis with low cost have been proposed.

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In the present work, an effective electrochemical sensor for the rapid and selective determination of epinephrine (EP) in the presence of uric acid (UA) based on a glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs) and cysteic acid was applied.

A novel voltammetric sensor was developed based on glassy carbon electrode (GCE) modified with a thin film of multiwalled carbon nanotubes (MWCNTs) coated with an electropolymerized layer of L-arginine. The resulting electrode was applied for simultaneous determination of Hydroquinone (HQ) and catechol (CC). The surface morphology and property of the modified electrode were characterized by scanning electron microscopy and electrochemical impedance spectroscopy techniques. Bare GCE fails to resolve the voltammetric signals of HQ and CC in a mixture. However, the modified electrode not only separates the voltammetric signals of HQ and CC, but also shows higher oxidation current for these molecules. CV and DPV results showed that the isomers can be detected selectively and sensitively at modified glassy carbon electrode with peak-to-peak separation about 111 mV. Under the optimized condition, the detection limits of CC and HQ are 40 and 62 nM (S/N = 3). The present electrode was applied to the simultaneous determination of HQ and CC in rain and tap water samples, which make it a promising candidate for designing an effective dihydroxybenzene sensor.

In the present study reported, fully electrochemical methodology was used to prepare a new nanocomposite on a glassy carbon electrode. Cysteic acid was formed by electrochemical oxidation of L-cysteine on the surface of a glassy carbon electrode (GCE) and used as a proper polymeric framework for deposition of Au nanoparticles (AuNPs). Field emission scanning electron microscopy (FESEM) was used for the surface characterization. It was shown that this composite electrode not only separates the voltammetric signals of hydroquinone (HQ) and catechol (CC), but also shows higher oxidation current for these molecules. Under the optimized condition, a linear dynamic range of 0.09 μmol dm−3 to 39.2 μmol dm−3 range for hydroquinone with the detection limit of 20 nM and from 0.09 μmol dm−3 to 39.2 μmol dm−3 for catechol with the detection limit of 60 nM were obtained. The proposed method was evaluated by determination of HQ and CC in rain and tap water samples with satisfactory results (recovery > 96%).