Electrochemical detection of ornidazole in commercial milk and water samples using an electrode based on green synthesis of silver nanoparticles using cellulose separated from Phoenix dactylifera seed.

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.

Recent trends on electrochemical determination of antibiotic Ciprofloxacin in biological fluids, pharmaceutical formulations, environmental resources and foodstuffs: Direct and indirect approaches.

In the last few decades, pharmaceuticals, credited with saving millions of lives, have emerged as a new class of environmental contaminants. These compounds can have both chronic and acute harmful effects on aquatic ecosystems and consequently on human health. Therefore, there is an urgent need for the development of extremely sensitive, portable, and low-cost devices to perform analysis. In the present review article, recent reports on the application of various voltammetric and photo-electrochemical techniques using different electrode materials for the determination of antibiotic Ciprofloxacin (CIPRO) are reported. This review provides an insight into direct and indirect electrochemical approaches as well as the photoelectrochemical methods used for the determination of CIPRO. Emphasis is put on the applications of unmodified and modified carbon-based electrodes considering the modifier, supporting electrolytes, analytical method, concentration range, limit of detection, and real matrices. Carbon-based electrodes are the most used materials attributed to their commercial availability, reduced cost, high chemical stability, and non-toxicity.

Phytotoxic effect of the insecticide imidacloprid in Phaseolus vulgaris L. plant and evaluation of its bioaccumulation and translocation by electrochemical methods.

The objective of this work is to study the toxicological effect of the imidacloprid (IMD) on common bean plants (Phaseolus vulgaris L) when used at high doses and its quantification by electrochemical method. Common bean plants were exposed to increasing concentrations of IMD and the different plant tissues were subjected to various analyses. The IMD detection in different tissues of the bean plant was performed after extraction on the metallic silver electrode using square wave voltammetry. The analytical and calibration parameters (Slope, correlation coefficient, linear range, detection limit and relative standard deviation) were calculated for the different plant tissues. The effect of different doses (5.0 × 10-3 to 5.0 × 10-2 mol L-1) of IMD was evaluated on germination, seedling (vigour, growth) and photosynthetic pigments in the bean plant. The results indicate that germination rate and seed vigour index reduced significantly (p ≤ 0.05) only in the applied concentrations above the recommended dose. A similar effect of IMD was observed on seedling development in term of roots length, plant length, number of leaves and number of nods. Concerning pigments content, chlorophyll a, b and total chlorophyll maximally decreased by 95.26%, 80.44% and 82.15% respectively at high applied dose. The bioaccumulation and translocation behaviour of IMD in bean plant was investigated, revealing that the IMD can be bioaccumulated in roots and can easily be translocated into stems and leaves.

Extraction and determination of flubendiamide insecticide in food samples: A review.

Flubendiamide (FBD) is the first commercially available phthalic acid diamide that targets ryanodine receptors (RyRs) in insects, which play a major role in lepidoptera control. However, excessive use of FBD can influence the quality of treated products leading to toxic effects on human health. The availability of rapid and convenient methods for evaluating FBD amount in the environment is necessary. Therefore, analytical methods were developed for the determination of residues of FBD and its metabolite desiodo in different food matrices like tomato, cabbage, pigeon pea, apple, chilli and rice. The current review carries forward methods for FBD residues analysis in foods by using several chromatographic techniques including sample preparation steps. The comparison between the different methods employed for quantitative and qualitative analysis of food quality and safety is also discussed. Liquid chromatography (LC) is the predominant analytical method for assessing the quality of foods treated with FBD. Studies related to LC coupled multichannel detector (Ultraviolet (UV), Mass spectrometry (MS)) are also applied to detect pesticide residues. Extraction and clean up steps are essential to obtain reliable results. Moreover, this review reports the allowed limits of residues for the safety of consuming products treated with FBD.

Complexation of amoxicillin by transition metals: Physico-chemical and antibacterial activity evaluation.

Some bacteria have developed resistance to antibiotics that were once commonly used to treat them. Moreover, this resistance has become more and more massive and worrying. During this work, we succeeded in synthesizing "metal-antibiotic" complexes, combining as a ligand for the metals of Cu (II), Zn (II) and Fe (III). These complexes AMX - M (M = Cu, Fe and Zn) were characterized by UV-Vis spectrophotometry, IR spectroscopy, and electrochemical methods. Job's method of continuous variation suggested 1:1 metals to ligand stoichiometry for all amoxicillin complexes. The binding constant/association constant (K) of the AMX with Zn(II), Cu(II), and Fe(III) were found to be 4.46 × 104, 7.17 × 102 and 7.65 × 102 L mol-1, respectively. The IR spectra shows that the ligands coordinated to the metal ions through amino, imino, carboxylate, ß-lactamic and carbonyl groups. The electrochemical results proved that amoxicillin oxidation process can be delayed by transition metal complexation. After, the complex synthesis, the antibacterial activity of ligand and its metal complexes were evaluated against Escherichia. coli bacteria by antibiogram method. The results show that the metal-amoxicillin complexes have better antibacterial activity against Escherichia coli (E. coli) than the free ligand (amoxicillin) due to the AMX protection against oxidation after complexation.

Recent knowledge in favor of remdesivir (GS-5734) as a therapeutic option for the COVID-19 infections.

The management of SARS-CoV-2 has not yet been clearly determined and is based on potential therapies evaluated during the SARS-CoV and MERS-CoV outbreaks. An emerging potential therapeutic approach currently being evaluated in numerous clinical trials is the remdesivir agent, which acts on COVID-19 by interfering with key steps in the virus replication cycle. It is considered a therapeutic option to be evaluated against COVID-19, based on data on its in vitro and in vivo activity against MERS-CoV and SARS-CoV coronaviruses. In this work, we provide an overview of remdesivir's discovery, mechanism of action, and the current studies exploring its clinical effectiveness. Recommendations for its use against COVID-19 infection are also summarized.

Current progress on COVID-19 related to biosensing technologies: New opportunity for detection and monitoring of viruses.

The technologies used for coronavirus testing consist of a pre-existing device developed to examine different pathologies, such as bacterial infections, or cancer biomarkers. However, for the 2019 pandemic, researchers knew that their technology could be modified to detect a low viral load at an early stage. Today, countries around the world are working to control the new coronavirus disease (n-SARS-CoV-2). From this perspective, laboratories, universities, and companies around the world have embarked on a race to develop and produce much-needed test kits. This review has been developed to provide an overview of current trends and strategies in n-SARS-CoV-2 diagnostics based on traditional and new emerging assessment technologies, to continuous innovation. It focuses on recent trends in biosensors to build a fast, reliable, more sensitive, accessible, user-friendly system and easily adaptable technology n-SARS-CoV-2 detection and monitoring. On the whole, we have addressed and identified research evidence supporting the use of biosensors on the premise that screening people for n-SARS-CoV-2 is the best way to contain its spread.

Review on the contamination of wastewater by COVID-19 virus: Impact and treatment.

Emerging viruses are a major public health problem. Most zoonotic pathogens originate in wildlife, including human immunodeficiency virus (HIV), influenza, Ebola, and coronavirus. Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a coronavirus called SARS-associated coronavirus (SARS-CoV). Viruses are charged colloidal particles that have the ability to adsorb on surfaces depending on pH. Their sorptive interaction with solid particles has important implications for their behavior in aquatic environments, soils, sewage sludge, and other solid materials and their removal or concentration by water treatment processes. Current state of knowledge on the potential of wastewater surveillance to understand the COVID-19 pandemic is reviewed. This study also identified wastewater irrigation systems with a higher risk of COVID-19 transmission. Emphasis was placed on methodologies for the detection and quantification of SARS-CoV-2 in wastewater.

Recent advances in electrochemical sensors for amoxicillin detection in biological and environmental samples.

Amoxicillin (AMX) is among the most successful antibiotics used for human therapy. It is used extensively to prevent or treat bacterial infections in humans and animals. However, the widespread distribution and excess utilization of AMX can be an environmental and health risk due to the hazardous potential associated to its pharmaceutical industries effluents. Besides, their extensive use in food animal production may result in some undesirable residues in food, e.g. meat, eggs and milk. Consequently, at high enough concentrations in biological fluids, AMX may be responsible of various diseases such as nausea, vomiting, rashes, and antibiotic-associated colitis. For this reason, the detection and quantification of amoxicillin in pharmaceuticals, biological fluids, environmental samples and foodstuffs require new electroanalytical techniques with sensitive and rapid measurement abilities. This review discusses recent advances in the development of electrochemical sensors and bio-sensors for AMX analysis in complex matrices such as pharmaceuticals, biological fluids, environmental water and foodstuffs. The main electrochemical sensors used are based on chemically modified electrodes involving carbon materials and nanomaterials, nanoparticles, polymers and biological recognition molecules.

Electrodeposition of silver onto carbon graphite and their catalysis properties toward thiamethoxam reduction: application in food and beverage samples.

The purpose of this paper is the electrodeposition of silver particles on graphite electrode (Ag@GrCE) using chronoamperometry and the use of this electrode for the determination of thiamethoxam. The electrode was prepared by chronoamperometry and characterized by X-Ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), EDX analysis and electrochemical impedance spectroscopy. The obtained electrode exhibits excellent electrocatalytic activity toward thiamethoxam reduction. The voltammetric response was linear as function of TXM concentration with a limit of detection around to 1.92 × 10-6 mol L-1. The proposed electrode was successfully used to analyze thiamethoxam residue in some food samples including orange and tomato juices.

Recent progress in controlling the synthesis and assembly of nanostructures: Application for electrochemical determination of p-nitroaniline in water.

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.

Design of a new low cost natural phosphate doped by nickel oxide nanoparticles for capacitive adsorption of reactive red 141 azo dye.

Nickel oxide doped natural phosphate (NP/NiO) nanoparticles were thermally synthesized for effective adsorption of Reactive Red 141 (RR141) as toxic dye model, characterization methods such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy combined with energy dispersive X-ray analysis(SEM-EDAX)and have been employed to identify the adsorbent. Surface area and pore size volume were determined by the Brunauer, Emmett and Teller (BET) method. Environmental factors such as pH, time of contact, initial RR141 concentration, the dose of adsorbent and solution temperature have been all put to the test to evaluate optimum adsorption activity. Thermal processing NP/NiO at 1% NiO doping percentage was effectual for exhibiting best adsorption behavior at an annealing temperature of 600 °C. Furthermore, batch experiments revealed significant adsorption activity reaching 96%. The maximal adsorption capacity was found to be 38.91 mg of RR 141 per 0.1 g of the adsorbent in only 40min of contact, at an initial colorant concentration of 20 mg L-1, pH 6 at ambient temperature and a volume of 100 ml. Langmuir isotherm model was more adequate to describe the adsorption process than the Freundlich model. The rate mechanism of the adsorption process was determined from the intraparticle diffusion model, Boyd plot revealed that the adsorption of the dye on the NP/NiO was mainly governed by film diffusion. Moreover, the dye adsorption was spontaneous and exothermic. The mechanism of adsorption may involve chemical adsorption through hydrogen bonding mechanism and electrostatic interactions between the dye molecules and the adsorbent. Thermal regeneration was feasible only for three cycles, the adsorbent also showed great potential for real textile wastewater treatment.

Electrochemical sensors for improved detection of paraquat in food samples: A review.

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.

Synthesis of silver nanoparticles assisted by chitosan and its application to catalyze the reduction of 4-nitroaniline.

This paper reports on the fabrication of material comprised of chitosan stabilized silver nanoparticles on the carbon paste and its electro-catalytic reduction toward 4-nitroaniline. The synthesized material was obtained when AgNO3 was mixed with chitosan as a stabilizing agent and NaBH4 as a reducing agent. The developed Chitosan-AgNPs has been confirmed using UV-Vis spectroscopy, X-Ray diffraction analysis, scanning electron microscopy (SEM) and infrared spectroscopy. The synthesized chitosan-Ag NPs exhibit particle size around 51 nm. To build a voltammetric sensor (Chitosan-Ag NPs/CPE), a carbon paste electrode has immersed in the liquid suspension of chitosan-Ag NPs, thus, it could be employed for electro-catalytic reduction of 4-NA in 0.1 M Britton-Robinson buffer solution (B-R, pH 2). Therefore, the reduction over-potential of 4-NA shifted from -752.26 mV at CPE to -304 mV at chitosan-Ag NPs/CPE, and then showing a surface controlled process with the catalytic rate constant (Kcat) of 0.125 × 10-3 M-1 s-1 and a coefficient of diffusion (D) of 2.20 × 10-6 cm2 s-1 with an enhanced current response. Under optimized conditions, the electro-catalytic reduction peak current of 4-NA increased linearly with increasing of 4-NA concentration over the range of 1 µM to 0.5 mM (R2 = 0.9866) with a detection limit of 0.86 µM (3 × Sb/P).

Voltammetric determination of nitro compound 4-nitroaniline in aqueous medium at chitosan gelified modified carbon paste electrode (CS@CPE).

A sensitive, selective and reproducible electrochemical method has been established for the electroanalysis of 4-nitroaniline (4-NA) using a carbon paste electrode modified with a chitosan solution gelled in acetic acid (CS@CPE). The modified electrode was then characterized spectroscopically using Fourier Transform Infrared (FTIR) spectroscopy. In addition, the electrochemical and interfacial characteristics of the as-prepared modified electrode were assessed by potentiodynamic cyclic voltammetry (CV) and AC electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was additionally used to deduce the trace amounts of (4-NA) in phosphate buffered saline (PBS) of pH7.0 as an ideal electrolyte. Under optimized conditions, the peak current of 4-NA increased linearly with the increasing 4-NA concentration over the range of 0.1µM to 0.1Mm. The calibration curve presents two linear ranges of current versus 4-NA concentration with a detection limit of 93.4nM (3sb/B). The repeatability of the current peak registered at CS@CPE was performed at a level of 0.5µM 4-NA employing one sensor on the same day for eight measurements. The relative standard deviation was 3.5%.

Rheological and electrical properties used to investigate the coagulation process during sludge treatment.

Analyses of rheological properties and electrical conductivity (σdc) at direct current have been employed in order to investigate the effects of calcium oxide on the coagulation process during sludge treatment in the textile industry. In this context, rheological and electrical measurements were performed on five samples - one that contained raw sludge and the other four that were prepared from the raw sludge and different amounts of calcium oxide: 2, 3, 4, 5% (w/w). Rheological behavior of these samples was analyzed using the Herschel-Bulkley modified model. The influence of calcium oxide content on the rheological parameters such as infinite viscosity, the yield stress, the consistency coefficient, and the consistency index, are presented and discussed. The impact of the calcium oxide content on pH and conductivity were also examined. Similar behaviors have been seen in the evolution of conductivity and infinite viscosity as a function of the calcium oxide content. These latter characteristics were modeled by an equation using two power laws. This equation was able to fit very well the evolution of electrical conductivity and also the viscosity versus the percentage of calcium oxide to predict the optimal amount of calcium oxide (3%) to achieve the coagulation step during sludge treatment.

Electrochemical impedance spectroscopy measurements for determination of derivatized aldehydes in several matrices.

A simple, selective and sensitive electrochemical method is described for the determination of different aldehydes at glassy carbon electrode using electrochemical impedance spectroscopy (EIS). The measurements were performed after their derivatization with 2,4-dinitrophenylhydrazine (DNPH) in acidic medium. The impedance measurements were investigated in the frequency range from 100 mHz to 100 kHz at a potential of 1.0 V versus Ag/AgCl. The Nyquist plots were modeled with a Randle's equivalent circuit. The charge transfer resistance was identified as the dependent parameter on relevant concentration of aldehydes (determined as their hydrazones). Under the optimized conditions, the linearity was established over the concentration range of 1000-0.05 µmol L-1. The limits of detection (LODs) obtained were from 0.097 to 0.0109 µmol L-1. Finally, the developed method has been applied to the determination of aldehydes in drinking water, orange juice and apple vinegar samples with relative standard deviations (RSDs) < 3.1% and acceptable recovery rate (around of 80%).

Ibuprofen analysis in blood samples by palladium particles-impregnated sodium montmorillonite electrodes: Validation using high performance liquid chromatography.

The electrochemical detection of ibuprofen has been studied on Palladium-Montmorillonite (Mt) modified carbon paste electrode using differential pulse voltammetry. The optimization of the modifier preparation and the instrumental parameters was investigated. The results indicate that ibuprofen oxidation was favored in the presence of Pd-PdO particles. The quantitative determination of ibuprofen was statistically analyzed and validated using HPLC method. The detection and quantification limits, specificity and precision were found to be acceptable. Finally, the developed method was successfully applied for ibuprofen determination in human blood samples.

Square wave voltammetric determination of paracetamol at chitosan modified carbon paste electrode: Application in natural water samples, commercial tablets and human urines.

A novel analytical approach has been developed and evaluated for the quantitative analysis of paracetamol (PCT). The anodic peak currents of paracetamol on the CS-CPE were about 200 fold higher than that of the unmodified electrodes. The influence of various parameters on the CS-CPE was investigated. Under the optimized working conditions, the oxidation peak current is linear to the paracetamol concentration in the ranges of 1.0 × 10(-3)-4.0 × 10(-4)mol L(-1) and 2.0 × 10(-4)-8.0 × 10(-7)mol L(-1) with a detection limit of 5.08 × 10(-7)mol L(-1). The repeatability of the method expressed as relative standard deviation (RSD) is 1.73% (n=8). Possible interferences were tested and evaluated in 1.0 × 10(-4)mol L(-1) paracetamol in the presence of inorganic ions, dopamine, ibuprofen, ascorbic acid and uric acid. The proposed method was successfully applied to PCT determination in natural waters, tablets and urine samples.

Sensitive determination of paraquat by square wave anodic stripping voltammetry with chitin modified carbon paste electrode.

A novel analytical approach has been developed and evaluated for the quantitative analysis of paraquat herbicides which can be found at trace levels in olive oil and olives. The aim of this work is to optimize all factors that can influence this determination by a carbon paste electrode modified with chitin (Chit-CPE). The best responses were obtained with square wave potential in diluted Na2SO4 as supporting electrolyte. The influence of various parameters on the Chit-CPE was investigated. Under the optimized working conditions, calibration graphs were linear in the concentration ranges of 5.0 × 10(-9)-1.0 × 0(-5) mol L(-1). For 180 s preconcentration, detection limits of 2.67 × 10(-10) mol L(-1) (peak 2) was obtained at the signal noise ratio (SNR) of 3. To evaluate the reproducibility of the newly developed electrode, the measurements of 1.0 × 10(-5) mol L(-1) PQ were carried out for seven times at Chit-CPE and the relative standard deviation was 5.2%. The analytical methodology was successfully applied to monitor the paraquat content in olives and olive oil.