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4-Aminoquinoline including Hydroxychloroquine (HCQ), amodiaquine (AQ), Chloroquine (CQ) are a quinoline with an amino group at the 4th position with a basic side chain. They are generally used as antimalarial medications. HCQ and CQ are recommended by the World Health Organization on march 2020 the use as a possible treatment to coronavirus (COVID–19). Long-term of 4-aminoquinoline drugs administration can be associated with toxic side-effects on the outer retina and the retinal pigment epithelium. Therefore, their determination in biological samples is important. Several methods have been used for 4-Aminoquinoline compounds analysis, such as spectrophotometry, immunological, electrophoresis, chromatography and electroanalytical methods. Electrochemical methods are more preferable because they are simple, quick analysis and more sensitive performance. Up to now, numerous electrochemical methods have been used to detect those drugs. Nevertheless, the utilization of later techniques is limited. Therefore, this review describes different electrochemical sensors, which are used for 4-aminoquinoline electroanalysis in complex matrices such as pharmaceuticals and biological fluids. For this, the fundamental analytical performance of the chosen sensors is investigated. The selectivity and oxidation mechanisms for 4-aminoquinoline reported in the literature were discussed. Also, the application of these sensors for 4-aminoquinoline monitoring in biological and environmental samples is reported. [ABSTRACT FROM AUTHOR]

The present research

In this paper, a simple chemical method is reported for the synthesis of silver nanoparticles using β‐1,4 poly D‐glucosamine as stabilizer agent and their application towards electrocatalytical determination of p‐nitrophenol (p‐NP). The formation of β‐1,4 poly D‐glucosamine capped silver nanoparticles was confirmed using UV‐Vis spectroscopy, Scanning Electronic Microscopy (SEM), and Fourier Transform Infrared (FTIR) spectroscopy. The electrocatalytic activity of the β‐1,4 poly D‐glucosamine capped silver nanoparticles modified graphite carbon electrode (β 1,4 p‐DGA‐AgNPs/GrCE) towards p‐NP was studied using cyclic voltammetry (CV), AC electrochemical impedance spectroscopy (EIS), and amperometric (i–t) studies. Typically, the obtained results were compared with those for unmodified graphite carbon. The results clearly reveal that the end prepared sensor has high electrocatalytic activity for p‐NP reduction. From the DPV results, (β 1,4 p‐DGA‐AgNPs/GrCE) was concluded as viable sensor for the electrochemical determination of p‐NP in a linear range from 1.0×10−6 to 1.0×10−4 mol L−1. The minimum calculated concentration that can be detected by the proposed electrode is 6.0×10−7 mol L−1 in terms of the detection limit ((3×σ)/P). [ABSTRACT FROM AUTHOR]

The development of nanoparticle research has grown considerably in recent years. One of the reasons for the considerable current interest in nanoparticles is because such materials frequently display unusual physical (structural, electronic, magnetic, and optical) and chemical (catalytic) properties. The development of nanomaterials is of interest to the scientific community and industrial companies. Different methods (physical, chemical, and biological) allow their manufacture. In particular, a major effort has been devoted to the development and improvement of synthesis methods in order to obtain nano-objects of controlled size and shape, a necessary pre-requisite to their organization, and to the study of their intrinsic and collective properties. Reviews play an important role in keeping interested parties up to date on the current state of the research in any academic field. This review aims to focus on the development of nanoparticles and stabilization with adsorbed/covalently attached ligands in solution phase since these factors are deeply related to the origins of the particles' stability, the media to which they are exposed, and the involved applications. This study also examines the factors that influence the synthesis of nanoparticles. It aims to provide an overview of existing electrochemical sensors, particularly those that operate with nanomaterial-based electrode modifications for p -nitroaniline (PNA) determination and to propose guidelines for related research and development activities. Emphasis was placed on the procedure for the analysis of PNA in water samples using nanosilver-based electrodes. Image 1 • Controlling the synthesis and assembly of nanostructure are discussed. • Metal−Support interactions on different types of metal species are stated. • PNA is a ubiquitous contaminant in the environment up to 100 mg L−1. • Procedures for PNA analysis in water using nanosilver-based electrodes are discussed. [ABSTRACT FROM AUTHOR]

Paraquat (1,10-dimethyl-4,40-dipyridinium chloride), also known as methyl viologen, is widely used as a quaternary ammonium herbicide (broadleaf weed killer) all over the world owing to its excellent effect in plant cells for crop protection and horticultural use. However, it is dangerous because of its high acute toxicity even at low concentrations. Its detection in the environment is therefore necessary. As a consequence of its widespread usage, it causes genotoxic, teratogenic as well as other environmental and ecological adverse impacts. Exposure to PQ leads to a high mortality rate because no specific drug is effective for treatment. Excessive consumption of PQ can cause cellular damage and necrosis in the brain, heart, lungs, liver, and kidneys. The diversity and sensitivity of the analyses currently required have forced the experimenter to use more advanced and efficient techniques, which can provide qualitative and quantitative results in complex environments. Electrochemical methods generally meet these criteria while offering other advantages to achieve excellent accuracy and fast handling. This paper provides an overview of the determination of PQ using electrochemical methods combined with several modified electrodes in food samples, including milk, apple juice, tomato juice, and potato juice. Emphasis was placed on the most relevant modifiers used to generate high selectivity and sensitivity such as noble metals, metallic nanoparticles, polymers, biomolecules, clay, and apatite minerals. Comprehensively, it is strongly convincing that the synergy between the sensor substrate and the modifier architecture gives the electrodes a high capacity to detect paraquat in complex matrices such as food. In line with the context, information's on the mechanism of electrooxidation or reduction of PQ has been reported with the discussion of some future prospects and some insights. To the best of our knowledge, there is no review article relating the electrochemical determination of paraquat. Image 1 • Paraquat could be an unsafe compound even at low concentrations. • Chemically modified electrodes have been developed for the detection of paraquat. • Nanomaterials, polymer, biomolecules, clay and mineral are used as modifiers. • The analytical process often coupled to different electrochemical methods. • paraquat has been investigated in food and vegetables and water samples. [ABSTRACT FROM AUTHOR]

The accumulation of harmful residuals can lead to voluminous environmental problems and then negatively affect human health. For this purpose, it is necessary to focus on the development of a rapid and sensitive strategy for its monitoring. In this work, a green, fairly fast, inexpensive and sensitive electrochemical sensor was developed to determine and monitor Cipro residues in various samples such as environmental resources, wastewater, urine, and drug formulations (Flonox 500 Aflox 500 and Cifloxine 250). It consists of a carbon paste electrode (CPE) modified with clay‐supported reduced graphene oxide composite (GrGO/CL@CPE). The rGO was prepared using green and easily chemically converted GO (electrochemically prepared) to rGO nanosheets based on glucose (G) as a green reducing agent (GrGO). The proposed sensor demonstrates a high electro‐oxidation signal compared with other based sensors, and the oxidation potential was found to be reduced by around 35 mV. The GrGO/CL@CPE was used for monitoring Cipro in the range of 0.05–10 μM in phosphate buffer at a biological pH of 7 (PB_7) and it offered a low detection limit (DL) (S/N=3) of 0.048 μM. Furthermore, it was found to be capable of detecting Cipro in pronounced samples with excellent results, offering promising prospects for actual clinical assays. [ABSTRACT FROM AUTHOR]

The widespread use of antibiotics has contributed to the control of disease and the nutritional well-being of livestock. Antibiotics reach the environment via excretions (urine and feces) from human and domestic animals, through non proper disposal or handling of unused drugs. The present study describes a green method for the synthesis of silver nanoparticle (AgNPs) using cellulose extracted from Phoenix dactylifera seed powder via mechanical stirrer method for the electroanalytical determination of ornidazole (ODZ) in milk and water samples. The cellulose extract is used as the reducing and stabilizer agent for the synthesis of AgNPs. The obtained AgNPs were characterized by UV–Vis, SEM and EDX, presenting a spherical shape and an average size of 48.6 nm. The electrochemical sensor (AgNPs/CPE) was fabricated by dipping a carbon paste electrode (CPE) in the AgNPs colloidal solution. The sensor shows acceptable linearity with ODZ concentration in the linear range from 1.0 × 10−5 to 1.0 × 10−3 M with a limit of detection (LOD =3S/P) and quantification (LOQ =10S/P) of 7.58 × 10−7 M and 2.08 × 10−6 M respectively. • Extraction of cellulose from Phoenix dactylifera seed and their characterization. • Utilization of the extracted cellulose in the synthesis of silver nanoparticles (AgNPs). • Preparation of new sensor based on synthesized AgNPs, to evaluate the electrocatalytic behavior of ODZ. • Electrochemical detection of ODZ in commercial milk and water samples using the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a thermally reduced graphene/clay/chitosan modified pencil electrode for ultrasensitive detection of Flubendiamide using differential pulse voltammetry. The graphene oxide was synthesized by exfoliation of graphite with an eco-friendly procedure. The as-produced reduced graphene/clay/chitosan composite is characterized by utilizing Fourier transform infrared spectroscopy and Scanning electron microscopy. The electrochemical behavior of the electrode before and after modification was investigated by cyclic voltammetry. Under optimized conditions, the reduced graphene/clay/chitosan modified pencil electrode exhibited excellent analytical properties toward Flubendiamide determination using differential pulse voltammetry. A linear calibration curve was established from 0.02 to 15 μmol L−1 for Flubendiamide with a limit of detection of 0.001 μmol L−1. The method was effectively employed for Flubendiamide detection in white rice samples. [Display omitted] • Natural clay intercalated with CHIT/rGO modified pencil electrode was synthesized. • Clay/CHI/rGO/PGE was applied for electrochemical sensing of FBD insecticide using DPV method. • Proposed modified electrode exhibits good results of stability, precision and selectivity. • Clay/CHI/rGO modified pencil electrode is suitable for analysis of FBD in rice samples. [ABSTRACT FROM AUTHOR]

Flubendiamide (FBD) is one of the compounds whose environmental impact of its decomposition products is still being studied in-depth, as it poses a significant hazard to the ecological environment and human health. Therefore, it is critical and essential to create a fast, easy, and sensitive method for detecting FBD in food and surface water samples. In this paper, a simple, economical, selective, and sensitive electrochemical sensor is proposed for the detection of FBD in surface water and white rice samples. It consists of a pencil graphite electrode (PGE) modified with Chitosan (CHI). The developed electroanalytical method was performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The different parameters influencing the cathodic peak current of FBD were optimized. After optimization, the sensor showed wide linear responses in the range from 5.0 × 10−7 mol L−1 to 1.0 × 10−5 mol L−1 of FBD concentration and provided a detection limit of 5.0 × 10−8 mol L−1. The PGE/CHI has good anti-interference properties, stability, and reproducibility due to the synergistic effect between PGE and CHI. The proposed sensor enabled the practical application of sensitive FBD detection in surface water and white rice samples with good recovery rates. [Display omitted] • Organic polymer modified pencil graphite electrodes (PGE/CHI) were prepared. • Electrochemical detection of FBD insecticides was performed by DPV and EIS techniques. • Reaction mechanism of FBD at PGE/CHI electrode has been discussed. • Proposed sensor was applied to determine FBD in water and white rice samples. [ABSTRACT FROM AUTHOR]

The present work describes a simple, inexpensive and green electrochemical sensor based on natural phosphate modified graphite paste electrode (NPh–CPE) for the electrocatalytic determination of HCQ. The NPh–CPE has demonstrated a high performance toward HCQ electro-oxidation compared to unmodified carbon paste electrode in terms of oxidation current and potential. The HCQ electrochemical behavior at NPh–CPE was studied using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Based on the investigation results, the electrode/analyte reaction characterization elucidates the E r C i mechanism as being a typical adsorption-controlled system. The response linearity, repeatability, accuracy and detection limit (LOD) were within the literature values range. The obtained detection limits were 5.27 × 10−7 mol L−1 and 3.34 × 10−7 mol L−1 for peak 1 and peak 2 respectively. The relative standard deviation (RSD) was found to be 2.8% for 5.0 × 10−6 mol L−1 of HCQ. The real samples analysis performed on human blood and pharmaceutical tablets have yielded satisfactory results. [Display omitted] • HCQ is determined by DPV using a natural phosphate modified carbon paste electrode. • Electrocatalytic HCQ oxidation was achieved by naturel phosphate. • The electrochemical oxidation mechanism of HCQ's peak 1 and 2 was established. • CV, EIS, CA technics confirmed the E r C i system nature. • The attained detection limit is comparable with other works. [ABSTRACT FROM AUTHOR]