Search

Biochar is a carbon rich and low-cost material that has been used as electrode modifier due to the property of preconcentrate spontaneously both organic and inorganic species. In this work, a biochar from coffee husks is proposed for the first time to prepare a carbon paste modified electrode (BC-CPE), which was used for the simultaneous determination of Cd2+ and Pb2+ by differential pulse adsorptive stripping voltammetry (DPAdsV) as proof-of-concept. Different BC-CPE were prepared, characterized (by EIS, FTIR, SEM and SEM–EDS) and submitted to DPAdsV measurements in the presence of both metal ions. Using the optimized BC-CPE (25 wt% of BC pyrolyzed at 300 °C during 50 min) and optimal pre-concentration conditions (10 min under stirring in a solution at pH 7.0), good linear range and LOD's better than other BC-CPE from literature (1.7 and 0.2 µg L−1 for Cd2+ and Pb2+, respectively) were obtained, as well as stable responses (RSD < 4.5%; n = 5) and good inter-electrode reproducibility (RSD < 4.4%; n = 5). This optimized method was applied for the simultaneous determination of Pb2+ and Cd2+in water samples, being found good accuracy (recoveries between 81 and 122%). The good analytical features favor the determination of these and other heavy metal ions at trace levels using the proposed BC-CPE, due to the strong ion adsorption on biochar pyrolyzed from coffee processing residues, a novel eco-friendly, sustainable, and renewable biochar source. [ABSTRACT FROM AUTHOR]

A new voltammetry method for the highly sensitive antidepressant drug vortioxetine (VOR) is presented using glassy carbon electrodes modified with hierarchical carbon nanofibers with NiCo nanoparticles (eCNF/CNT/NiCo-GCE). The electrochemical behavior of VOR was investigated by cyclic voltammetry, which indicates that its oxidation is an adsorption-controlled process with the exchange of two electrons and one proton. The effects of various factors on the VOR peak, such as supporting electrolyte type, preconcentration time, and potential, or influence of interferents, were tested using the square wave voltammetry technique (SWV). The linear voltametric response for the analyte was obtained in the concentration range from 0.01·10−6 to 3.0·10−6 mol L−1 with the detection limit of 1.55·10−9 mol L−1 for a preconcentration time of 60 s. The proposed method was successfully applied for highly sensitive VOR determination in complex matrices such as tablets, urine, and plasma with good recovery parameter. [ABSTRACT FROM AUTHOR]

This study is the stage of developing a phenol detection electrochemical sensor. Phenol is one of the organic pollutants harmful to human life and ecosystems. The development of this sensor was carried out by studying the use of TiO2 anatase as a modifier of graphene electrodes. The mass of TiO2 anatase was varied, while the mass of graphene and paraffin was fixed. The results showed that the TiO2 mass of 1.0 g was the best mass as a graphene electrode modifier. The use of this mass increases the oxidation current (Ipa) of phenol by 450 A, which is observed at an oxidation potential (Epa) of −0.30 V. The presence of interfering ions such as K+, Fe2+, and OH− can decrease the measurement current. However, based on the %RSD value, it shows that the performance of TiO2-graphene is in a good category, where the %RSD value obtained is 0.6%. TiO2-graphene electrodes can be used repeatedly for 12 days. Overall, this work demonstrates the potential of TiO2-graphene electrodes as electrode candidates for electrochemical-based phenol sensors. [ABSTRACT FROM AUTHOR]

The article discusses the proposed model for energetics at conjugated electrolyte/electrode modifier for organic electronics and their implications on design rules. Topics discussed include the equilibration of the Fermi level due to oxidation, additional interface dipole step and the achievement of the smallest charge injection/extraction barrier.

Highlights: [•] Adsorbed monomers and their polymers can have different influences on formic acid oxidation at Pt electrodes. [•] Pyrrole and indole inhibit formic acid oxidation at Pt while polypyrrole and polyindole activate the electrode. [•] Aniline and carbazole can activate Pt for formic acid oxidation as both adsorbed monomers and polymers. [•] It is suggested that the orientation of the modifier as well as its hydrophobicity are key elements in determining its influence on formic acid oxidation. [ABSTRACT FROM AUTHOR]

Thanks to operational simplicity, speediness, possibility of miniaturization and real-time nature, electrochemical sensing is a supreme alternative for non-electrochemical methodologies in drug quantification. This review, highlights different nanotech-based sensory designs for electroanalysis of isoniazid and rifampicin, the most important medicines for patients with tuberculosis. We first, concisely mention analyses with bare electrodes, associated impediments and inspected possible strategies and then critically review the last two decades works with focus on different nano-scaled electrode modifiers. We organized and described the materials engaged in several categories: Surfactants modifiers, polymeric modifiers, metallic nanomaterials, carbon based nano-modifiers (reduced graphene oxide, multi-walled carbon nanotubes, ordered mesoporous carbon) and a large class of multifarious nano composites-based sensors and biosensors. The main drawbacks and superiorities associated with each array as well as the current trend in the areas is attempted to discuss. Summary of 79 employed electrochemical approaches for analysis of isoniazid and rifampicin has also been presented. • An overview of the clinical significance of precise quantifications of isoniazid and rifampicin is offered. • Necessity of developing sensing approaches instead of non-sensing methodologies for the analysis is deliberated. • Different electrode nano- and nanobio-modifiers for electroanalysis of the drugs are classified and critically reviewed. [ABSTRACT FROM AUTHOR]