The behavior of a modified carbon paste electrode (CPE) for
para-nitrophenol detection by cyclic and square wave voltammetry (SWV) was studied. The electrode was built by incorporating the ...hydroxyapatite (HAP) to carbon paste. The overall analysis involved a two-step procedure: an accumulation step at open circuit, followed by medium exchange to a pure electrolyte solution for the voltammetric quantification. During the preconcentration step,
para-nitrophenol was adsorbed onto hydroxyapatite surface. The influence of various experimental parameters on the HAP–CPE response was investigated (i.e. pH, carbon paste composition, accumulation time). Under the optimized conditions, the reduction peak shows that the peak height was found to be directly proportional to the
para-nitrophenol concentration in the range comprised between 2
×
10
−7
mol
L
−1 and 1
×
10
−4
mol
L
−1. With this, it was possible to determine detection limit (DL), which resulted in 8
×
10
−9
mol
L
−1 for peak 1. The proposed electrode (HAP–CPE) presented good repeatability, evaluated in term of relative standard deviation (R.S.D.
=
2.87%) for
n
=
7 and was applied for
para-nitrophenol determination in water samples. The average recovery for these samples was 86.2%.
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.
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•Evidence for the presence of COVID-19 in wastewater•Detection methods and prevalence of viruses in wastewater•Knowledge needs for public health.•Recommendations on research and investigation priorities
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.
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•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.
In this work, the authors present an activated carbon modified carbon paste electrode that has superior electrocatalytic activity for the electro-oxidation of dopamine (DA), paracetamol (PCT) and ...salicylic acid (SA). This excellent electrochemical performance was referred to the porous structure of activated carbon, surface functional groups existing in activated carbon surface and the electron donor–acceptor complex mechanism assumes that the aromatic rings of the drugs act as the electron acceptors. However, the reaction mechanisms of the corresponding electrode were studied in detail in this article. Additionally, under the optimized experimental conditions, DA, SA and PCT exhibit a linear response over the range of 0.1–1000.0 μmol L−1, with the low detection limits of 0.0313 μmol L−1, 0.0282 μmol L−1 and 0.0487 μmol L−1 for DA, PCT and SA, respectively. Furthermore, the AC-CPE showed a high sensitivity, good reproducibility and high stability. The proposed method was applied successfully for the detection of DA, PCT and SA in human blood and pharmaceutical formulations with satisfactory recovery.
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•A sensitive electrochemical sensor of DA, PCT and SA was successfully developed.•AC/CPE shows good electrocatalytic performance for simultaneous detecting drugs.•Proposed sensor exhibited good reproducibility, stability and low detection limit.•Developed method was satisfactorily applied to analyze the drugs in real samples.
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•Electrochemical detection of amoxicillin (AMX)•Types of chemically modified electrodes for AMX detection.•Indirect electrochemical methods for AMX analysis.•Analysis of Amoxicilin in ...several real 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.
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•A new “metal-antibiotic” complexes were synthesized and characterized.•The Job’s method of continuous variation was used.•The binding constants (K) of the complexes AMX − M (M = Cu, ...Fe and Zn) were calculated.•AMX − M complexes antibacterial activity was evaluated against E. coli.
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, β-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.
In this work, determination of cadmium(II) using square wave voltammetry (SWV) was described. The method is based on accumulation of these metal ions on kaolin platinum electrode (K/Pt). The K/Pt ...performance was optimized with respect to the surface modification and operating conditions. The optimized conditions were obtained in pH of 5.0 and accumulation time of 25
min. Under the optimal conditions, the relationship between the peak current versus concentration was linear over the range of 9
×
10
−8 to 8.3
×
10
−6
mol
L
−1. The detection limit (DL, 3
σ) was 5.4
×
10
−9
mol
L
−1. The analytical methodology was successfully applied to monitor the Cd(II) content in natural water. Interferences were also evaluated.
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 5.0×10−9–1.0×0−5molL−1. For 180s preconcentration, detection limits of 2.67×10−10molL−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 1.0×10−5molL−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.
•The chitin polymer was used as modifier of carbon paste electrode to determine paraquat.•The influence of square wave voltammetry parameters was investigated.•The chitin modified carbon paste electrode was tested on olive and olive oils samples.
•The extraction of chitosan by deacetylation of chitin.•Preparation of the sample from chitin from crustacean shells.•Description of the adsorption by Langmuir-type isotherm and Freundlich-type ...isotherm.•Theoretical calculation of UV–Vis spectra and optical parameters.
Chitin, extracted primarily from exoskeleton shellfish, is one of the most abundant biopolymer in the world. It is estimated to be produced annually almost as much as cellulose.
The development of fishing activities in Morocco (coastline of 3500km on both the Atlantic and the Mediterranean) induced an important fish industry waste. The aim of this work is to recover chitin, extracted from shellfish waste, and chitosan, produced by deacetylation of chitin, in the adsorption of organic pesticide 2,4-dichlorophenoxyacetate (2,4-D). The chitosan samples were prepared from chitin from crustacean shells. The chitin deacetylation was carried out in aqueous sodium hydroxide. Characterization of chitin and chitosan was performed by infrared spectroscopy, nuclear magnetic resonance and theoretical calculation of UV–Vis spectra and optical parameters. Analysis of theoretical spectra shows a substantial sensitivity to the hydroxyl and amino groups. The presented hydroxyl group in chitin determines the conformation of the molecule and also the stereochemistry of chemical reactions and kinetics. The presence of functional groups causes the substantial changes of both absorption spectra as well as permanent dipole moment. The adsorption of 2,4-D by chitin and chitosan was performed at different pH values, the pesticide-adsorbent contact time and initial pesticide concentration. The adsorption is described by Langmuir-type isotherm and Freundlich-type isotherm. Recovery tests of 2,4-D confirm the initial interest in using chitin and chitosan as a depolluting agent.
The purpose of this paper is to fabricate graphene oxide (GO) from carbon rods of spent (ZnC) batteries using a new optimized approach in electrochemical applications. The proposed method-based ...sonication for the recycling of carbon rods was adopted as a fast and economical process via a less aggressive pathway. The energy reaction time and explosion problems were avoided by the proposed protocol. The waste graphite powder (carbon rods) and the powder produced by the developed method-based sonication (SGO) were characterized by UV–Visible, XRD, FTIR and SEM. The electrochemical performance of the prepared SGO was evaluated by cyclic voltammetry (CV) and current-voltage (I–V) techniques. The results revealed that SGO has a higher electrocatalytic property compared to the graphene oxide by the standard Hummers method (HGO).
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∙Sonication-assisted oxidation and exfoliation process was recycled for graphene oxide (SGO) production.∙The carbon powder of (ZnC) batteries rods and its graphene oxide (SGO) were characterized.∙The energy and reaction time along with explosion problems were avoided by the proposed approach.∙Electrochemical performances of SGO were investigated and compared to the Hummers graphene oxide (HGO).
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