An Efficient Electrochemical Sensor Based on NiCo2O4 Nanoplates and Ionic Liquid for Determination of Favipiravir in the Presence of Acetaminophen.

Based on the modification of carbon paste electrode with NiCo2O4 nanoplates and 1-hexyl-3-methylimidazolium tetrafluoroborate, a new electrochemical sensing platform for the sensing of favipiravir (a drug with potential therapeutic efficacy in treating COVID-19 patients) in the presence of acetaminophen was prepared. For determining the electrochemical behavior of favipiravir, cyclic voltammetry, differential pulse voltammetry, and chronoamperometry have been utilized. When compared to the unmodified carbon paste electrode, the results of the cyclic voltammetry showed that the proposed NiCo2O4 nanoplates/1-hexyl-3-methylimidazolium tetrafluoroborate/carbon paste electrode had excellent catalytic activity for the oxidation of the favipiravir in phosphate buffer solution (pH = 7.0). This was due to the synergistic influence of 1-hexyl-3-methylimidazolium tetrafluoroborate (ionic liquid) and NiCo2O4 nanoplates. In the optimized conditions of favipiravir measurement, NiCo2O4 nanoplates/1-hexyl-3-methylimidazolium tetrafluoroborate/carbon paste electrode had several benefits, such as a wide dynamic linear between 0.004 and 115.0 µM, a high sensitivity of 0.1672 µA/µM, and a small limit of detection of 1.0 nM. Furthermore, the NiCo2O4 nanoplates/1-hexyl-3-methylimidazolium tetrafluoroborate/carbon paste electrode sensor presented a good capability to investigate the favipiravir and acetaminophen levels in real samples with satisfactory recoveries.

ZnO Hollow Quasi-Spheres Modified Screen-Printed Graphite Electrode for Determination of Carmoisine.

Food colorants are important in food selection because they improve the gastronomic appeal of foods by improving their aesthetic appeal. However, after prolonged use, many colorants turn toxic and cause medical problems. A synthetic azo-class dye called carmoisine gives meals a red color. Therefore, the carmoisine determination in food samples is of great importance from the human health control. The current work was developed to synthesis ZnO hollow quasi-spheres (ZnO HQSs) to prepare a new electrochemical carmoisine sensor that is sensitive. Field emission-scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) have been used to analyze the properties of prepared ZnO HQSs. A screen-printed graphite electrode (SPGE) surface was modified with ZnO HQSs to prepare the ZnO HQSs-SPGE sensor. For carmoisine detection, the ZnO HQSs-SPGE demonstrated an appropriate response and notable electrocatalytic activities. The carmoisine electro-oxidation signal was significantly stronger on the ZnO HQSs-SPGE surface compared to the bare SPGE. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CHA), and differential pulse voltammetry (DPV) have been utilized to investigate the suggested protocol. The DPV results revealed an extensive linear association between variable carmoisine concentrations and peak current that ranged from 0.08 to 190.0 µM, with a limit of detection (LOD) as narrow as 0.02 µM. The ZnO HQSs-SPGE's ability to detect carmoisine in real samples proved the sensor's practical application.

Graphite carbon nitride-modified screen-printed electrode as a highly sensitive and selective sensor for detection of amaranth.

This work presented a particular electrochemical sensor for analysis of amaranth, an azo toxic dye. A graphite nitride carbon (g-C3N4) was used to modify an electro-treated screen-printed electrode (g-C3N4/SPE) for electroanalysis of amaranth. Physicochemical characteristics and analytical performance of g-C3N4/SPE were investigated by relevant equipment. The g-C3N4/SPE when comparing with bare SPE, possessed an impressive electrocatalytic performance towards the amaranth oxidation. As-developed sensor under the optimal circumstances exhibited an extended linear response range for different amaranth concentrations of 0.08 µM-340.0 µM, with a narrow practical limit of detection (LOD) of 0.02 µM, a limit of quantification (LOQ) of 0.08 µM, and an unparalleled sensitivity of 0.0702 µA/µM using differential pulse voltammetry (DPV). The applicability of as-fabricated sensor was verified by determining the amaranth in real samples, with acceptable recoveries.

Amplified electrochemical sensor employing screen-printed electrode modified with Ni-ZIF-67 nanocomposite for high sensitive analysis of Sudan I in present bisphenol A.

This study utilized a facile one-pot protocol to synthesize Ni-cobalt zeolitic imidazolate framework (Ni-ZIF-67) nanocomposite, which was then characterized by Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and scanning electron microscopy. The Ni-ZIF-67 nanocomposite was subsequently applied to modify a screen-printed electrode (SPE) as a durable sensor for detection of Sudan I concomitantly with bisphenol A (BPA), with remarkably increased electrochemical response when comparing with a bare SPE. The results showed the calibration plot to be linear in the concentration range between 0.03 µM and 535.0 µM, with a narrow limit of detection of 9.0 nM (S/N = 3). Our proposed protocol was successful in detecting target analytes in real tap water and food specimens.

Fast and efficient removal of Pb(II) ion and malachite green dye from wastewater by using magnetic activated carbon-cobalt nanoparticles.

A high-surface-area and inexpensive activated carbon has been produced from lemon peel using chemical activation with H3PO4 at 500 °C in a N2 atmosphere. Afterwards, the synthesized cobalt nanoparticles using coprecipitation method were adsorbed on the activated carbon surface, and as a result magnetic activated carbon was obtained. Sample characterization has been assessed via X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and magnetic properties. It was found that magnetic activated carbon-cobalt nanoparticles (MAC/Co) synthesized had a high saturation magnetization. The MAC/Co revealed super-paramagnetic behaviors at room temperature, and have been readily isolated from solution by using an exterior magnet. Next, adsorption behavior of malachite green and Pb(II) onto the generated MAC/Co has been examined. Sorption kinetics and equilibrium have been studied using batch procedure. The kinetic and isothermal adsorption results were matched completely with the Elovich and Langmuir models, respectively. Based on the Langmuir model, the highest adsorption capacities of malachite green dye and Pb(II) ion respectively were 263.2 and 312.5 mg g-1 at room temperature. Based on the results, the MAC/Co is a probable economic and effective adsorbent that can be employed as a new adsorbent to remove malachite green dye and Pb(II) from wastewater.

Recent developments in electrochemical sensors for detecting hydrazine with different modified electrodes.

The detection of hydrazine (HZ) is an important application in analytical chemistry. There have been recent advancements in using electrochemical detection for HZ. Electrochemical detection for HZ offers many advantages, e.g., high sensitivity, selectivity, speed, low investment and running cost, and low laboriousness. In addition, these methods are robust, reproducible, user-friendly, and compatible with the concept of green analytical chemistry. This review is devoted to the critical comparison of electrochemical sensors and measuring protocols used for the voltammetric and amperometric detection of the most frequently used HZ in water resources with desirable recovery. Attention is focused on the working electrode and its possible modification which is crucial for further development.

An innovative synthesis of MoO3/Ag nanocomposite and catalytic application of immobilized molybdenum complex on cellulose extracting from Carthamus tinctorius.

Extracted microcrystalline cellulose from Carthamus tinctorius plant was oxidized by sodium metaperiodate and a novel molybdenum schiff base complex was supported on this natural cellulose (MoSMC@MC). Then, micro biopolymer silver/ immobilized molybenum complex on natural cellulose (Ag/MoSMC@MC) was synthesized at the presence of Sesbania sesba plant and charaterized by SEM, FT-IR, TGA, and EDAX. The catalytic efficiency of Ag/MoSMC@MC was exploited as a heterogenous bio-catalyst in the selective oxidation of alcohols. The reactions were conducted using catalytic amounts of Ag/MoSMC@MC and t-BuOOH under solvent free conidtion to obtain desired aldehydes and ketones in high yields and excellent selectivity. Long-term stability and reproducibility in consecutive runs were feature of this microcomposite. At second part of this work, a novel strategy was reported to obtain green nanocomposites. Herein, addition of silver nitrate to plant solution led to the decomposition of the organic to inorganic polymer. As results, MoO3/Ag nanocomposite was prepared and its characteristics were investigated using TEM, and XRD to confirm the shape and structure.

Simultaneous Separation and Preconcentration of Trace Amounts of Cu(II), Ni(II), Zn(II), and Cd(II) with Modified Nanoporous Pumpellyite Zeolite.

A procedure for determination of trace levels of Cu(II), Zn(II), Ni(II), and Cd(II) by flame atomic absorption spectrometry using a preconcentration system has been proposed. In this system, we used modified nanoporous pumpellyite zeolite loaded with 2-phenyl-4-[1-(2-thienyl) methylidene]-5-oxazolone as a sorbent for extracting Cu(II), Zn(II), Ni(II), and Cd(II) ions from real samples. Several parameters such as pH of the sample solution, amount of nanoporous pumpellyite zeolite, amount of ligand, volumes of sample and eluent, type of eluent, flow rates of sample and eluent, and the effects of diverse ions on the preconcentration were investigated. The LODs for Cu(II), Zn(II), Ni(II), and Cd(II) in the original solution were 2.6, 1.3, 3.2, and 1.1 ng/mL, respectively. The preconcentration factor was 250 for Zn and Ni, 100 for Cd, and 125 for Cu. The developed method was applied to the determination of trace metal ions in certified reference material tea leaves and water samples with satisfactory results.

Selective ligandless cloud point extraction of palladium from water and dust samples.

In this study, the phase-separation phenomenon of non-ionic surfactants was used for separation and preconcentration of Pd(II). The cloud point extraction (CPE) method is based on the formation of PdI2 which is then entrapped in the non-ionic surfactant Triton X-114. Ethanol acidified with 0.5 M HNO3 was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometry. The main factors affecting CPE efficiency, such as sample solution pH, concentration of iodide ion and Triton X-114, equilibration temperature and time, were all investigated and optimized. At optimum conditions, a calibration curve was constructed for the determination of palladium according to the ligandless CPE procedure. Linearity was maintained between 1.0 to 500.0 ng/mL. The LOD based on three times the SD of the blank divided by the slope of analytical curve, (3Sb/m) was 0.3 ng/mL. Seven replicate determinations of a solution containing of 4.0 µg palladium gave a mean absorbance of 0.359 with RSD±1.85%. The high efficiency of CPE to carry out the determination of palladium in complex matrixes was demonstrated. The proposed method has been applied to the determination of trace amounts of palladium in a platinum-iridium alloy, water, and dust samples, with satisfactory results.

Electrochemical determination of hydrazine using a ZrO2 nanoparticles-modified carbon paste electrode.

In the present paper, the use of a carbon paste electrode modified by 3-(4'-amino-3'-hydroxy-biphenyl-4-yl)-acrylic acid (3,4'AA) and ZrO2 nanoparticles prepared by a simple and rapid method was described. The heterogeneous electron transfer properties of (3,4'AA) coupled to ZrO2 nanoparticles at the carbon paste electrode were investigated using cyclic voltammetry, chronoamperometry, and square wave voltammetry in aqueous buffer solutions. Under the optimized conditions, the square wave voltammetric peak currents of hydrazine increased linearly with hydrazine concentrations in the range of 2.5 × 10(-8) to 5.0 × 10(-5) M, and detection limit of 14 nM was obtained for hydrazine. Finally, this modified electrode was used for the determination of hydrazine in water samples, using standard addition method.

One-pot and efficient synthesis of triazolo[1,2-a]indazole-triones via reaction of arylaldehydes with urazole and dimedone catalyzed by silica nanoparticles prepared from rice husk.

A novel synthesis of triazolo[1,2-a]indazole-1,3,8-trione derivatives by reaction of urazole, dimedone and aromatic aldehydes under conventional heating and microwave irradiation and solvent-free conditions using silica nanoparticles prepared from rice husk ash as catalyst is described. The new method features high yields, multicomponent reactions and environmental friendliness.

Flame atomic absorption spectrometry determination of trace amounts of nickel ions in water samples after ligandless ultrasound-assisted emulsification microextraction.

In the present work, a new ligandless-ultrasound-assisted emulsification microextraction (LL-USAEME) method was developed for preconcentration trace amounts of nickel as a prior step to its determination by flame atomic absorption spectrometry. Some factors influencing the extraction efficiency of nickel and its subsequent determination were studied and optimized, such as type and volume of the extraction solvent, pH, extraction time, extraction temperature and ionic strength. Under the optimal conditions, the calibration curve was linear over the range of 1.0 ng mL(-1) - 1.0 µg mL(-1) for nickel with R(2) = 0.9997. The detection limit was 0.34 ng mL(-1) in the original solution (3S(b)/m) and the relative standard deviation for 8 replicate determination of 0.3 µg mL(-1) nickel was ±1.6%. The proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 97 - 103% were obtained.

Ligandless dispersive liquid-liquid microextraction for the separation of trace amounts of silver ions in water samples and flame atomic absorption spectrometry determination.

In this article, a new ligandless dispersive liquid-liquid microextraction method has been developed for preconcentration of trace quantities of silver as a prior step to its determination by flame atomic absorption spectrometry. In the proposed approach, carbon tetrachloride and ethanol were used as extraction and dispersive solvents. Several factors that may be affected on the extraction process, like, extraction solvent, disperser solvent, the volume of extraction and disperser solvent, pH of the aqueous solution and extraction time were optimized. Under the optimal conditions, the calibration curve was linear in the range of 5.0 ng mL(-1) to 2.0 microg mL(-1) of silver with R(2)=0.9995 (n=9) and detection limit based on three times the standard deviation of the blank (3S(b)) was 1.2 ng mL(-1) in original solution. The relative standard deviation for eight replicate determination of 0.5 microg mL(-1) silver was +/-1.5%. The high efficiency of dispersive liquid-liquid microextraction to carry out the determination of silver in complex matrices was demonstrated. The proposed method has been applied for determination of trace amount of silver in standard and water samples with satisfactory results.

Ligandless-dispersive liquid-liquid microextraction of trace amount of copper ions.

In the present work, a new ligandless-dispersive liquid-liquid microextraction (LL-DLLME) method has been developed for preconcentration trace amounts of copper as a prior step to its determination by flame atomic absorption spectrometry. In the proposed approach 1,2-dicholorobenzene and ethanol were used as extraction and dispersive solvents, respectively. Some factors influencing on the extraction efficiency of copper and its subsequent determination were studied and optimized, such as the extraction and dispersive solvent type and volume, pH of sample solution, extraction time and salting out effect. Under the optimal conditions, the calibration curve was linear in the range of 1.0 ng mL(-1)-0.6 microg mL(-1) of copper with R(2)=0.9985. Detection limit was 0.5 ng mL(-1) in original solution (3S(b)/m) and the relative standard deviation for seven replicate determination of 0.2 microg mL(-1) copper was +/-1.4%. The proposed method has been applied for determination of copper in standard and water samples with satisfactory results.