Anodic Peak Current Research Articles

Adrenaline biosensors based on r Go/Ag nanocomposites functionalized textiles using advanced electron beam irradiation technique

This study developed flexible textile biosensors based on rGO/Ag nanocomposite to detect adrenaline (epinephrine). Reduced graphene oxide (rGO) and Ag nanoparticles (NPs) were obtained in a single step using the electron-beam irradiation technique, a rapid, efficient, plain, ecofriendly, and easily scalable procedure. The nanocomposites’ properties were characterized by ultraviolet–visible-light spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Furthermore, the obtained sensors’ electrochemical behaviors of epinephrine were investigated using square wave voltammetry (SWV), linear sweep voltammetry, and differential pulse voltammetry methods. The optimum experimental conditions included pH 7, phosphate borate buffer, accumulation time of 100 s, accumulation potential of 0.4 V, and a scan rate of 100mV/s. In addition, the anodic peak currents of epinephrine by SWV were 16.33 and 13.9 µA for rGO/AgNP/cotton and rGO/AgNP/polyester, respectively. The fabricated flexible textile biosensors exhibited high sensitivity and strong catalytic activity for epinephrine detection. Under optimal testing conditions, in the range of 0.5–100.0 µL, two detection lines and a low limit of detection (LOD) of 9.73 nM (S/N = 3) for epinephrine were obtained for cotton and polyester biosensors. Two wide detection ranges were observed at 0.5–40.0 µL for cotton biosensors, whereas there was a lower LOD of 3.05 nM (S/N = 3) at 1.0–30 µL for polyester biosensors. Overall, the constructed electrode can serve as a promising analytical sensor for adrenaline determination in pharmaceutical and biological samples.

Electrooxidation and Development of a Highly Sensitive Electrochemical Probe for Trace Determination of the Steroid 11-Desoxycorticosterone Drug Residues in Water

Anabolic-androgenic steroids (AASs), a class of compounds frequently misused by competitors and unfortunately by the general population, have lately attracted international attention. Thus, extraordinary demands for developing low cost, precise, rapid, and facile protocols for detection and/or determination of AAS have arisen. Hence, the current strategy explores for the first time the redox features of 21-hydroxypregn-4-ene-3, 20-dione, namely, 11-desoxycorticosterone (DCS) AA drug steroid at a glassy-carbon electrode (GCE) in a wide pH range (pH 2.0–10.0) by adsorptive differential pulse-anodic stripping voltammetry (DP- ASV) and cyclic voltammetry (CV). At pH 2, DP-ASV and CV at the optimized pH 2–3 displayed an irreversible anodic peak at 0.4 V versus Ag/AgCl electrode. The dependency of the anodic peak current of the CV at 0.4 V at various concentrations and scan rate of the DCS drug was characteristic of an electrode-coupled electron transfer of EE type mechanism. At the optimized parameters, the proposed strategy allowed quantification of DCS in the concentration range 2.5 -13.19 nM (0.83-4.36 ng mL−1) with satisfactory limits of detection (LOD) and quantization (LOQ) of 9.3 × 10−1 nM (3.1 × 10−1 ng mL−1) and 3.1 nM (1.02 ng mL−1), respectively. A relative standard deviation (RSD) of ±3.93% (n = 5) at 4.0 ng mL−1 DCS was achieved. The established probe was fruitfully employed and validated for trace determination of DCS residues in environmental water. The interference of several common diverse species on DCS sensing was insignificant revealing good selectivity. The established probe exhibited good sensitivity, selectivity, precision, and accuracy, short analytical time, and low cost compared with the reported methods, for DCS determination.

Hydrothermal synthesis of CuFe2O4 nanoparticles for highly sensitive electrochemical detection of sunset yellow

The sunset yellow, as a synthetic food coloring azo dye, was detected in the present work using a new sensitive and selective sensor based on the modification of screen-printed electrode surface with Copper ferrite nanoparticles (CuFe2O4/SPE). Thus, a facile hydrothermal protocol was performed to prepare the CuFe2O4 nanoparticles, followed by characterization applying valid techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and field-emission scanning electron microscopy (FE-SEM). Chronoamperometry, differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were employed to determine the electrochemical behavior of as-fabricated sensor. According to the electrochemical findings, a greater anodic peak current was found for the sunset yellow oxidation on the CuFe2O4/SPE than that on the unmodified SPE. The electrocatalytic response for the sunset yellow oxidation on the CuFe2O4/SPE in phosphate buffer (0.1 M, pH = 7.0) was effective, with an excellent sensitivity (0.1919 μA μM−1). There was a linear relationship between the voltammetric current and different sunset yellow concentrations (0.03–100.0 μM). The calculated limit of detection (LOD = 3Sb/m) for the sunset yellow was 0.009 μM.

Natural deep eutectic solvent: A novelty alternative as multi-walled carbon nanotubes dispersing agent for the determination of paracetamol in urine.

This work reports for the first time the analytical performance of glassy carbon electrodes (GCE) modified with a dispersion of multi-wall carboxylated carbon nanotubes (MWCNTs-COOH) using a mixture of a natural deep eutectic solvent (NADES - LGH/lactic acid-glucose-water), ethylene glycol (EG) and water (GCE/MWCNT-LGH-EG) for the determination and N-(4-hydroxyphenyl) acetamide (paracetamol) (APAP) in urine samples. The optimization of both dispersion and measurement conditions was carried out using experimental design. The modified electrode exhibited enhanced current responses, demonstrating excellent electrochemical response towards APAP oxidation compared to MWCNTs-LGH, MWCNTs-EG, MWCNTs-H2O-EtOH and MWCNTs-H2O. The linear dependence between the anodic peak currents and the square root of scan rates over the range of 0.010-0.300 Vs-1 demonstrates that the electro oxidation of APAP occurs under diffusional control. The MWCNT-LGH-EG modified GCE displayed an analytical sensitivity of 10.72mLμg-1 (r=0.9994) and a detection limit of 100ngmL-1 for the selective determination of APAP in urine samples. The proposed electrochemical sensor was successfully applied for quantifying APAP in urine samples in the presence of uric acid. In addition, the accuracy and precision of the method was contrasted against a HPLC reference method.

Colloidal synthesis of perovskite-type lanthanum aluminate incorporated graphene oxide composites: Electrochemical detection of nitrite in meat extract and drinking water.

A novel electrochemical method has been developed for determination of nitrite using La-based perovskite-type lanthanum aluminate nanorod-incorporated graphene oxide nanosheets (LaAlO3@GO). Morphological and structural analyses of the prepared perovskite-type electrocatalyst, with and without a glassy carbon electrode (GCE) surface, were performed using various techniques, including transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry, Raman spectroscopy, and electrochemical impedance spectroscopy. Under optimal conditions, the LaAlO3@GO composite-modified GCE (LaAlO3@GO/GCE) exhibited excellent electrocatalytic performance toward the electrooxidation of nitrite (pH = 7.0), with a significant increase in anodic peak currents compared with the bare GCE. Using amperometry, the fabricated sensor exhibited a wide nitrite determination range from 0.01 to 1540.5µM, with a detection limit of 0.0041µM. Notably, the proposed LaAlO3@GO/GCE electrode demonstrated a good nitrite detection performance in different meat and water samples. In addition, the LaAlO3@GO/GCE electrode displayed excellent selectivity, repeatability, reproducibility, storage, and operational stability toward nitrite detection.

Electrochemical biosensor based on Temporin-PTA peptide for detection of microorganisms

Bacterial and fungal infections are challenging due to their low susceptibility and resistance to antimicrobial drugs. For this reason, antimicrobial peptides (AMP) emerge as excellent alternatives to overcome these problems. At the same time, their active insertion into the cell wall of microorganisms can be availed for biorecognition applications in biosensing platforms. Temporin-PTA (T-PTA) is an AMP found in the skin secretions of the Malaysian fire frog Hylarana picturata, which presents antibacterial activity against MRSA, Escherichia coli, and Bacillus subtilis. In this work, T-PTA was explored as an innovative sensing layer aiming for the electrochemical differentiation of Klebsiella pneumoniae, Acinetobacter baumannii, Bacillus subtilis, Enterococcus faecalis, Candida albicans, and C. tropicalis based on the structural differences of their membranes. The biosensor was analyzed through electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). In this approach, the different structural features of each microorganism resulted in different adherence degrees and, therefore, different electrochemical responses. The transducing layer was fabricated by the self-assembling of a 4-mercaptobenzoic acid (MBA) monolayer and gold-capped magnetic nanoparticles (Fe3O4@Au) implemented to improve the electrical signal of the biointeraction. We found that each interaction, expressed in variations of electron transfer resistance and anodic peak current, demonstrated a singular response from which the platform can discriminate all different microorganisms. We found expressive sensitivity towards Gram-negative species, especially K. pneumoniae. A detection limit of 101 CFU.mL−1 and a linear range of 101 to 105 CFU.mL−1 were obtained. The T-PTA biosensor platform is a promising and effective tool for microbial identification

Emphasis on the incorporation of Tropaeolin OO dye and silver nanoparticles for voltammetric estimation of flibanserin in bulk form, tablets and human plasma

A novel electrochemical sensor based on the electro-deposition of silver nanoparticles (AgNPs) on Tropaeolin OO (poly-TO) layers over pencil graphite electrode (PGE) surface was fabricated for the first time for voltammetric determination of flibanserin (FBS); a drug enhances female sexual performance. Further characterization studies using cyclic voltammetry (CV), square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were conducted. The AgNPs synergistic effect on poly-TO layers facilitates the FBS electro-oxidation in phosphate buffer solution (pH 6.0) and its determination in bulk form, tablets and in human plasma. Following ICH guidelines, validation of the proposed SWV method for FBS analysis was successfully achieved using the fabricated sensor (AgNPs@poly-TO/PGE). Under the optimal instrumental and experimental conditions, the anodic oxidation peak current was directly proportional to FBS concentration in the range from 0.1 to 8.5 μmol L−1 with low detection and quantitation limits (0.0286 and 0.0867 μmol L−1, respectively). High sensitivity, selectivity as well as easiness of fabrication are the main advantages of the modified sensor.

Gold nanoparticle decorated patronite on rGO for the quantification of sulfadiazine at nanomolar levels in contaminated water

Sulfadiazine (SDZ) contamination of the aquatic environment has been a critical concern in recent years due to its negative impacts on public health and ecological systems, and a reliable method is required to quantify it at ultra-low levels content in wastewater. We synthesized nanocomposite electrodes consisting of gold nanoparticles decorating VS2-reduced graphene oxide sheets (AuNP/VS2-rGO composites) on screen-printed carbon electrode (SPCE) using a facile hydrothermal method and used them for the in situ electrochemical quantification of SDZ at nanomolar levels in environmental water samples. Electrochemical impedance spectroscopy (EIS) results exhibited low resistance and high conductance on AuNP-VS2-rGO/SPCEs (Rct = 78 Ω). Under optimized conditions, the proposed sensor shows outstanding electrocatalytic performance ability to oxidize SDZ and produce significantly higher anodic peak currents than rGO/VS2 or VS2 composite. The AuNP-VS2-rGO/SPCEs exhibited threshold concentration ranges between 10 and 345 nM and impressive sensitivity (0.1015 µA nM-1cm−2) for the SDZ sensor. The detection limit for these electrodes was 0.44 nM, which meets requirements for environmental sample analysis. The produced AuNP-VS2-rGO/SPCEs provided satisfactory reusability, stability, and anti-interference performance. Practically, these electrodes could be used to quantify SDZ and other toxic or hazardous pollutants in waste aqueous samples at nanomolar concentrations with acceptable recoveries.

Highly efficient carbon hybrid supported catalysts using nano-architecture as anode catalysts for direct methanol fuel cells

PtCo based nanoparticles in alloy structure were synthesized using the microwave-assisted reduction method. These nanoparticles were deposited on different carbon supporting materials. Here, these supporting materials such as rGO (reduced graphene oxide), rGO-VC (vulcan carbon) and AC-VC (activated carbon-vulcan carbon) were used and the methanol oxidation reaction (MOR) activity of single carbon support and hybrid carbon support material in the presence of PtCo nanoparticles were investigated at the same molar concentration. The average particle size of the PtCo nanoparticles detected in the TEM analysis was found to be 3.55 ± 0.64 nm. The MOR activity of the PtCo@rGO, PtCo@rGO-VC and PtCo@AC-VC catalysts was determined, where the anodic peak current of PtCo@AC-VC was determined as 73 mA/cm2. It has been observed that PtCo nanoparticles with carbon hybrid support structures are more advantageous than single support structures due to the synergistic effect between carbon support structures and providing a larger surface area. Compared to previous studies, the MOR activity of PtCo@AC-VC is quite high. It can be stated that PtCo@AC-VC has comparable catalytic activity compared to the commercial available anode catalyst.

Construction of a New Sensor with Copper(II) Complex Anchored in Calcium Phosphate Intercalated with m-Aminobenzoic Acid and Their Application in Determination of Dopamine

Crystalline lamellar calcium phosphate retained m-aminobenzoic acid inside its cavity without leaching. The intense infrared bands in the 1,033 cm−1 and 1,010 cm−1 intervals confirmed the presence of the phosphate groups attached to the inorganic layer, with sharp and intense peaks in X-ray diffraction patterns, which gave basal distances of 535 pm and 947 pm for the original and the intercalated compounds, respectively. The adsorption isotherm of copper(II) on a calcium phosphate host intercalated with m-aminobenzoic acid was studied in ethanol solution to give a maximum adsorption capacity of 1.43 mmoL g−1. The material was incorporated into carbon paste electrode and its electrochemical properties were investigated. However, for a dopamine solution, an enhancement of the anodic peak current was detected due to the electrocatalytic oxidation. The electrode presented the same response for at least 150 successive measurements, with a good repeatability. The modified electrode is very stable and reproducible. The sensor was applied for dopamine determination in pharmaceutical preparation (one commercial sample (Revivan)) with success.

Preparation, characterization and super electrocatalytic sensing study of polyaniline@yttrium phosphate (PANI@Y(III)PO4) nanocomposite

Synthesis of Y(III) phosphate-functionalized polyaniline nanocomposite (PANI@Y(III)PO4) was achieved through sol–gel method. The synthesized PANI@Y(III)PO4 was characterized by various techniques including Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA)-Differential thermal analysis (TGA-DTA) and direct current (DC) electrical conductivity. Efficient employment for the nanocomposite as modifier glassy carbon electrode was characterized by electrochemical impedance spectroscopy (EIS) and cyclicvoltametry (CV). The modified electrode showed a powerful enhancing effect and great stability in electrochemical sensing of the heavy metal ion Pb(II), giving an anodic peak current with a formal potential of - 0.195 V in acetic solution. The electrochemical parameters of the proposed sensor such as exchange current density (ⅉ0), active surface area of PANI@Y(III)PO4 modified GCE (A), surface coverage (Γ) of Pb (II) on the surface of PANI@Y(III)PO4, transfer coefficient (α) and number of electrons (n) involved in the electro-reduction, were found to be 92.21 μA cm-2, 0.27 cm2, 3.24×10-7 mol cm-2, 0.26 and 1.6 ≈ 2, respectively. Two voltametric techniques namely CV and linear sweep voltammetry (LSV) studies exhibited that the anodic peak current was linearly dependent on the concentration of Pb(II) with a broad dynamic range of 2.85–199.92 μM and 2.85–62.85 μM, respectively. However, the LSV method showed the highest sensitivity (5.58 μA μM-1 Cm-2) and the lowest detection limit (0.04 μM).

Development of an Electrochemical Sensing System for Wine Component Analysis

In this work, we developed a polyaniline (PANI)-modified electrochemical sensor chip via electrochemical polymerization that resists nonspecific adsorption for wine component (SO2, phenolic/organic acids) analysis using electrochemical analysis, cyclic voltammetry (CV). The red, rosé, and white wines were clearly discriminated by the PANI sensor chip based on their components, and the detection was a reversible process. The standard solution was investigated electrochemically for the determination of SO2 and compared with the standard Rankine method. The anodic peak currents were used for the SO2 measurement, and a good correlation was obtained (R2 = 0.9953). PANI electrode was characterized by electrochemical impedance spectroscopy (EIS). The charge transfer resistance (Rct) decreased with decreasing pH. A miniaturized homemade Rankine apparatus was also developed for portable use in the on-site assessment of free and bound sulfur dioxide (SO2) in wine. To our knowledge, this is the first report of a PANI-modified electrochemical sensor chip for wine component analysis.

Electrochemically Monitoring Reactive Oxygen Species with Antioxidants

Reactive oxygen species (ROS), such as the superoxide anion radical (O2˙–) are highly reactive species. In the body, O2˙– is naturally generated via a single electron reduction of molecular oxygen (O2).1-3 Excess production of ROS has been linked to cellular death and the onset of some pathological diseases.3 The activity of antioxidants is directly related to their ability to donate an electron, thereby acting as a scavenger to prevent possible cell damage and associated health complications. Antioxidants such as flavonoids may coordinate with metal ions to form metallo-flavonoid complexes, which may influence the antioxidant properties of the flavonoid.3 The role of metallo-flavonoid complexes as antioxidants toward O2˙– is not fully understood. Herein, cyclic voltammetry (CV) was used for electrochemical generation of the O2˙–/ O2 redox couple. The O2˙–/ O2 associated anodic and cathodic peak currents were monitored in the absence and presence of the flavonoid, quercetin (QCR) and its metallo- complexes.4 Overall, data exhibited a decrease in both redox signals, suggesting antioxidant behavior and O2 reactivity with the additive. L. Zabik, S. Anwar, I. Ziu, S. Martic-Milne, Electrochim. Acta, 296, 174-180 (2019).Ahmed, F. Shakeel, Czech J. Food Sci., 30, 153-163 (2012).M. Kasprzak, A. Erxleben, J. Ochocki, RSC Adv., 5, 45853-45877 (2015).Lewis, W. Wallace, F. Dingman Peterson, S. Rafferty, S. Martic, Electrochem Sci Adv, e2100054 (2021).

Simultaneous electrochemical determination of DNA nucleobases using AgNPs embedded covalent organic framework.

Anefficient electrochemical biosensor has beendeveloped for the simultaneous evaluation of DNA bases using AgNPs-embedded covalent organic framework (COF). The COF (p-Phenylenediamine and terephthalaldehyde) was synthesized by reflux (DMF; 150°C; 12h) and the nanoparticles were embedded from the aqueous solutions of AgNO3 and NaBH4. The nanocomposite-modified COF was confirmed by spectral, microscopic, and electrochemical techniques. The nanocomposite material was deposited on aglassy carbon electrode (GCE) and the redox behavior of AgNPs was confirmed by cyclic voltammetry. The electrocatalytic activities of DNA bases were analyzed by differential pulse voltammetry (DPV) in a physiological environment (PBS; pH = 7.0) based on simple and easy-to-use electrocatalyst. The AgNPs-COF/GCE showed well-defined anodic peak currents for the bases guanine (+ 0.63V vs. Ag/AgCl), adenine (+ 0.89V vs. Ag/AgCl), thymine (+ 1.10V vs. Ag/AgCl), andcytosine (+ 1.26V vs. Ag/AgCl) in a mixture as well as individuals with respect to the conventional, COF, and AgNPs/GCEs. The AgNPs-COF/GCE showed linear concentration range of DNA bases from 0.2-1000µM (guanine; (G)), 0.1-500µM (adenine (A)), 0.25-250µM (thymine (T)) and 0.15-500µM (cytosine (C)) and LOD of 0.043, 0.056, 0.062, and 0.051µM(S/N = 3), respectively. Thedeveloped sensor showedreasonable selectivity, reproducibility (RSD = 1.53 ± 0.04%-2.58 ± 0.02% (n = 3)), and stability (RSD = 1.22 ± 0.06%-2.15 ± 0.04%; n = 3) over 5days of storage) for DNA bases. Finally, AgNPs-COF/GCE was used for the determination of DNA bases in human bloodserum, urine and saliva samples with goodrecoveries (98.60-99.11%, 97.80-99.21%, and 98.69-99.74%, respectively).

An Efficient Novel Electrochemical Sensor for Simultaneous Determination of Vitamin C and Aspirin Based on a PMR/Zn‐Al LDH/GCE

AbstractA sensitive, low‐cost, and simple electrochemical sensor based on Zn−Al layered double hydroxide (Zn−Al LDH) combined with a polymer film of methyl red (PMR) to modify a GCE has been created for the first time. Using cyclic voltammetry (CV), the electrochemical characteristics of the newly fabricated sensor were investigated. The characterised PMR/Zn−Al LDH/GCE shows high electro‐catalytic activity towards the vitamin C (AA) and aspirin (ASA) oxidation. Schematic fabrication of PMR/Zn−Al LDH/GCE for the determination of AA or ASA was presented. The new sensor demonstrated superior analytical efficiency for the simultaneous identification of AA and ASA traces in well‐spaced anodic peaks, even in the presence of certain intervening species. According to experimental results, the fabricated sensor represented two well‐separated oxidation peaks for AA and ASA oxidation with potential difference of 799 mV (vs. Ag/AgCl). The linear dependences of the anodic peak currents of AA and ASA on their concentrations in the ranges of 0.10–53.17 μM are good. The detection limits of AA and ASA at the PMR/Zn−Al LDH/GCE were found to be 1.26 and 1.27 μM, respectively. Meanwhile, the quantification limits of AA and ASA were calculated as 4.21 and 4.25 μM, respectively. On other hand, the limit of detection (LODs) of AA and ASA oxidation were determined to be 0.47 and 0.21 μM, respectively, according to DPV method. The effect of scan rate (100 to 800 mV/s) on the anodic peak currents of AA and ASA was examined. A sensing model mechanism has been suggested and discussed in detail. Finally, the proposed sensor displayed a good reproducibility, stability and selectivity. The developed sensor was eventually used to successfully detect AA and ASA in urine samples.

Voltammetric determination of rutin in fruit juice samples using a 2 mercaptobenzothiazole coated pencil graphite electrode

A disposable modified electrode was developed to determine rutin based on a 2-mercaptobenzothiazole (2-MBT) coated pencil graphite electrode (PGE) surface. The modified surface (2-MBT/PGE) was characterized using Fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical techniques (cyclic voltammetry (CV) and differential pulse voltammetry (DPV)) were used to study the electrochemical properties of the modified electrode that was developed for the rutin identification. The effective electroactive surface area of PGE (bare PGE, 0.0134 cm2) increased by coating with 2-MBT on PGE (2-MBT/PGE, 0.286 cm2). At pH 4.5 in Britton-Robinson buffer, the anodic peak currents increased linearly with two concentration intervals of rutin. One of them is 0.039–1.1 μmol L−1, while the other is 1.1–10.5 μmol L−1. The detection limit was 9.6 nmol L−1 (3 s/m). Under the optimized conditions the oxidation peak current of rutin on 2-MBT/PGE increased at about 10 times compared with the bare PGE. The developed electrode was successfully applied for the determination of rutin in fruit juice samples and revealed spike recoveries in the range of 99.0–100.2 %.

A convenient strategy for the electrochemical evaluation of acetaminophen and caffeine in combined drugs and biological samples over TiO2@polymethyldopa/Pd nanocomposite functionalized glassy carbon electrodes

In this study, a sensitive electrochemical sensor was designed based on Pd nanoparticles adorned poly-methyldopa (PMDA) modified TiO2 nanoparticles embedded over glassy carbon electrode (TiO2@PMDA/Pd/GCE) for the simultaneous quantitative estimation of acetaminophen (AC) and caffeine (CF) in biological and pharmaceutical samples. Several analytical techniques like Fourier Transformed Infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDX) were used to characterize the as synthesized nanocomposite. Electrochemical properties of the constructed sensor were evaluated using cyclic voltammetry (CV). Following the optimization of some experimental parameters in differential pulse voltammetry (DPV), the anodic peak currents for both the molecules were found to be linear with their corresponding concentrations ranging from 5 nM to 3.5 µM and 50 nM to 4.5 µM respectively. Detection limits for AC and CF molecules were being 1.94 nM and 23.9 nM in this estimation. The fabricated sensor was advantageous in terms of ease of preparation, great stability, excellent selectivity, repeatability and reproducibility. To evaluate of electrode-to-electrode reproducibility the relative standard deviation (RSD%) were obtained to be 3.6% for AC and 4.5% for CF, respectively. The precision was measured to be below 4.3% for AC and 3.9 for CF, and accuracy between −1.7% − 3.5% for AC, and −3.7–2.5 for CF, respectively. Statistical student's t-test and F-test displayed negligible systematic error between the measured and real values and also between voltammetric method at the surface of the suggested electrode and standard HPLC method.

Preparation and characterization of a pencil graphite electrode modified with gold nanoparticles decorated poly (l-methionine) and its use in the simultaneous sensitive electrochemical analysis of ascorbic acid, acetaminophen, chlorpheniramine maleate, and caffeine

The current work outlines the use of an easy electrochemical sensor (AuNP-p(l-met)/PGE) based on pencil graphite electrode modified with gold nanoparticles-decorated poly(l-methionine) for the simultaneous anodic voltammetric analysis of four active drug substances, namely, ascorbic acid (A), acetaminophen (ACP), chlorpheniramine maleate (CP) and caffeine (CF). The surface characterization of the sensor was carried out using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) Spectroscopy, Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS). The electrode fabrication conditions (scan rate and the number of cycles) and some experimental parameters (pH, methionine, and HAuCl4 concentrations) were optimized by using Differential Pulse Voltammetry (DPV), and the results showed that the determination of A, ACP, CP, and CF could be performed at the same potential window, with the oxidation peak potentials properly separated. Compared to bare PGE, AuNP/p(l-met)/PGE can significantly improve the electrocatalytic activity for the oxidation of A, ACP, CF, and especially CP with a remarkable increase in anodic peak currents, at an extent of 30.9%, 10.5%, 31.7%, and 663.8%, respectively. The sensor showed an excellent performance in the determination of A, ACP, CP, and CF with a wide linear working range from 10 to 2000 μM; 3.18–3000 μM; 9.74–718 μM and 8.3–2000 μM; along with low detection limits of 3.03 μM; 0.95 μM; 2.92 μM and 2.50 μM, respectively. The method was successfully applied for the simultaneous quantification of A, ACP, CP, and CF at pharmaceutical dosages and in serum samples. The results obtained from pharmaceutical dosages were compared with those found by the HPLC method. The recovery and t-test results confirm the accuracy and precision of the developed AuNP-p(l-met)/PGE sensor, and no significant discrepancies were observed (95% confidence level).

Simultaneous Electrochemical Determination of Paracetamol and Allura Red in Pharmaceutical Doses and Food Using a Mo(VI) Oxide‐Carbon Paste Microcomposite

AbstractThis work presents a new application for MoO3 combined with carbon paste to prepare a microcomposite electrode (Mo(VI)Ox/CPE) for the simultaneous determination of paracetamol (PCM) and Allure Red (AR) by square‐wave voltammetry (SWV). The anodic peak currents for PCM and AR were 70.0 and 80.0 % high compared with an unmodified carbon paste electrode. The surface areas of Mo(VI)Ox/CPE and CPE were evaluated by cyclic voltammetry. The detection limit were 0.14 and 0.38 μmol/L for PCM and AR respectively. The relative standard deviations (RSDs) were 2.0 % (n=7). Stability, shelf life and possible interferences were also evaluated with very acceptable results.

Hybridized 1D–2D MnMoO4–MXene nanocomposites as high-performing electrochemical sensing platform for the sensitive detection of dihydroxybenzene isomers in wastewater samples

Hydroquinone (HQ) and catechol (CC) are the two major dihydroxybenzene isomers, are considered one of the toxic pollutants in wastewater, which often coexisted and impede each other during sample identification. For practical analysis and simultaneous detection of HQ and CC in wastewater, we fabricate a hybrid electrochemical sensor with electrospun one-dimensional (1D) MnMoO4 nanofibers coupled with a few-layered exfoliated two-dimensional (2D) MXene. The facilitated abundant defective edges of 1D MnMoO4 and 2D MXene nanoarchitecture accelerated the effect of synergistic signal amplification and exhibited high electrocatalytic activity towards the oxidation of hydroquinone and catechol. MnMoO4–MXene-GCE showed oxidation potentials of 0.102 V and 0.203 V for hydroquinone and catechol, respectively. It revealed the distinguished and simultaneous detection range of 0.101 V with a strong anodic peak current. Noteworthily, the proposed 1D–2D hybridized MnMoO4–MXene–GCE sensor exhibited a wide linear response from 5 nM to 65 nM for hydroquinone and catechol. Moreover, it showed a low detection limit of 0.26 nM and 0.30 nM for HQ and CC with high stability, respectively. The feasible 1D–2D MnMoO4–MXene nanocomposite-based biosensor effectively detected hydroquinone and catechol in hazardous water pollutants using the differential pulse voltammetric technique with recovery values.