Electrochemical Determination of Nitrite by Au Nanoparticle/Graphene-Chitosan Modified Electrode

Electrochemical sensors play a significant role in detecting chemical ions, molecules, and pathogens in water and other applications. These sensors are sensitive, portable, fast, inexpensive, and suitable for online and in-situ measurements compared to other methods. They can provide the detection for any compound that can undergo certain transformations within a potential window. It enables applications in multiple ion detection, mainly since these sensors are primarily non-specific. In this paper, we provide a survey of electrochemical sensors for the detection of water contaminants, i.e., pesticides, nitrate, nitrite, phosphorus, water hardeners, disinfectant, and other emergent contaminants (phenol, estrogen, gallic acid etc.). We focus on the influence of surface modification of the working electrodes by carbon nanomaterials, metallic nanostructures, imprinted polymers and evaluate the corresponding sensing performance. Especially for pesticides, which are challenging and need special care, we highlight biosensors, such as enzymatic sensors, immunobiosensor, aptasensors, and biomimetic sensors. We discuss the sensors’ overall performance, especially concerning real-sample performance and the capability for actual field application.

Section: Electrochemical Sensor For Water Contaminantsmentioning

confidence: 99%

A Review of Nanocomposite-Modified Electrochemical Sensors for Water Quality Monitoring

Kanoun

Lazarević‐Pašti

Pašti

et al. 2021

“…Mo et al modified GO-chitosan (CS) mixed film on GCE, then electrodeposited AuNPs on the surface of GO-CS/GCE by electrodeposition method [80]. The Au/GO-CS/GCE was used for the highly sensitive detection of nitrite.…”

Section: Metalsmentioning

confidence: 99%

Application of Graphene-Based Materials for Detection of Nitrate and Nitrite in Water—A Review

Wang

et al. 2019

Nitrite and nitrate are widely found in various water environments but the potential toxicity of nitrite and nitrate poses a great threat to human health. Recently, many methods have been developed to detect nitrate and nitrite in water. One of them is to use graphene-based materials. Graphene is a two-dimensional carbon nano-material with sp 2 hybrid orbital, which has a large surface area and excellent conductivity and electron transfer ability. It is widely used for modifying electrodes for electrochemical sensors. Graphene based electrochemical sensors have the advantages of being low cost, effective and efficient for nitrite and nitrate detection. This paper reviews the application of graphene-based nanomaterials for electrochemical detection of nitrate and nitrite in water. The properties and advantages of the electrodes were modified by graphene, graphene oxide and reduced graphene oxide nanocomposite in the development of nitrite sensors are discussed in detail. Based on the review, the paper summarizes the working conditions and performance of different sensors, including working potential, pH, detection range, detection limit, sensitivity, reproducibility, repeatability and long-term stability. Furthermore, the challenges and suggestions for future research on the application of graphene-based nanocomposite electrochemical sensors for nitrite detection are also highlighted.Sensors 2020, 20, 54 2 of 35 deaths. Nitrite in drinking water can irreversibly convert hemoglobin into methemoglobin, which results in a decrease in oxygen carrying capacity in the blood [5]. It can react with secondary amines to produce n-nitrosamines, which are likely to lead to gastric cancer [6]. Since nitrate is converted into nitrite in the digestive tract, it also very harmful to the human body [7]. It can also lead to the unnatural reproduction of aquatic plants and algae, leading to "red tides" and the death of fish [8,9]. The United States (U.S.) Environmental Protection Agency has limited the nitrite and nitrate content in drinking water to 1 mg/L and 10 mg/L [10] and other countries have made similar regulations. The concentration of nitrate and nitrite in water has become one of the indexes for evaluating water quality. Therefore, the detection of nitrate and nitrite in water samples at low concentrations has been the focus of research [11].So far, many methods have been used to detect nitrate and nitrite, such as spectrophotometry [12][13][14], chemiluminescence [15,16], chromatography [17], fluorescence [18,19] and electrochemical methods [20][21][22]. Among them, the electrochemical method is one of the most commonly used detection methods because of its advantages of being low cost, fast, direct and high efficiency [23]. However, the sensitivity and accuracy of the electrodes are reduced because of disturbance by other substances. Bare electrodes need higher applied potential, which limits the application of bare electrodes [24]. Therefore, electrochemical techniques based on modified electrodes have been extensively...

“…It can be employed in the form of various derivatives or composites and it is often represented by a gel structure [14]. Applications of these materials include primarily electrochemical biosensors [15,16]. Still, these materials are also applied in both chemoresistive [17,18] and mass [19] sensors at room temperature, owing to the sensing mechanism that should include swelling due to vapor adsorption and dipole-dipole interaction/hydrogen bonding influenced by analyte nature and diffusion regime [20].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Elastic Properties and Conductivity of Chitosan Acetate Films in Ammonia and Water Vapors Using Acoustic Resonators

Зайцев

Teplykh

Fedorov

et al. 2020

Novel bio-materials, like chitosan and its derivatives, appeal to finding a new niche in room temperature gas sensors, demonstrating not only a chemoresistive response, but also changes in mechanical impedance due to vapor adsorption. We determined the coefficients of elasticity and viscosity of chitosan acetate films in air, ammonia, and water vapors by acoustic spectroscopy. The measurements were carried out while using a resonator with a longitudinal electric field at the different concentrations of ammonia (100–1600 ppm) and air humidity (20–60%). It was established that, in the presence of ammonia, the longitudinal and shear elastic modules significantly decreased, whereas, in water vapor, they changed slightly. At that, the viscosity of the films increased greatly upon exposure to both vapors. We found that the film’s conductivity increased by two and one orders of magnitude, respectively, in ammonia and water vapors. The effect of analyzed vapors on the resonance properties of a piezoelectric resonator with a lateral electric field that was loaded by a chitosan film on its free side was also experimentally studied. In these vapors, the parallel resonance frequency and maximum value of the real part of the electrical impedance decreased, especially in ammonia. The results of a theoretical analysis of the resonance properties of such a sensor in the presence of vapors turned out to be in a good agreement with the experimental data. It has been also found that with a growth in the concentration of the studied vapors, a decrease in the elastic constants, and an increase in the viscosity factor and conductivity lead to reducing the parallel resonance frequency and the maximum value of the real part of the electric impedance of the piezoelectric resonator with a lateral electric field that was loaded with a chitosan film. This leads to an increase in the sensitivity of such a sensor during exposure to these gas vapors.