Differential Pulse Voltammetry Analysis Research Articles

Ultrasonic fabrication of neodymium oxide@titanium carbide modified glassy carbon electrode: An efficient electrochemical detection of antibiotic drug nitrofurazone

BackgroundPharmaceutical wastes have become a worldwide issue of environmental pollution due to even a low concentration of pharmaceuticals in the environment which has more adverse effects on wildlife and human health. Among the various pharmaceutical drugs, the antibiotic drug nitrofurazone (NZ) is harmful to public health due to cariogenic, mutagenic, and genotoxic behavior. Hence, the detection of NZ is essential for the ecosystem. MethodsHerein, we demonstrate the facile ultrasonic method to synthesize neodymium oxide@ titanium carbide (NdO@TC) electrocatalyst for the detection of NZ. The as-synthesized materials were confirmed through the XRD, FTIR, FESEM, HRTEM, EDX, and XPS analysis. Furthermore, the electrochemical behaviors were evaluated by using CV and DPV analysis. Significant findingsThe hybrid of NdO@TC coated on a glassy carbon electrode (GCE), shows prominent electrochemical detection of NZ owing to low charge transfer resistance and large surface area phenomena. Moreover, the differential pulse voltammetry (DPV) endows an excellent limit of detection (2.7 nm), sensitivity (0.1914 µA µM−1 cm−2), and a wide linear range of 0.01-2231 µM towards NZ detection. The fabricated electrode was practically utilized for the NZ determination in human urine, blood serum, and tap water samples to reveal adequate recovery results.

Electrocatalysis of 2,6-Dinitrophenol Based on Wet-Chemically Synthesized PbO-ZnO Microstructures

In this approach, a reliable 2,6-dinitrophenol (2,6-DNP) sensor probe was developed by applying differential pulse voltammetry (DPV) using a glassy carbon electrode (GCE) decorated with a wet-chemically prepared PbO-doped ZnO microstructures’ (MSs) electro-catalyst. The nanomaterial characterizing tools such as FESEM, XPS, XRD, UV-vis., and FTIR were used for the synthesized PbO-doped ZnO MSs to evaluate in detail of their optical, structural, morphological, functional, and elemental properties. The peak currents obtained in DPV analysis of 2,6-DNP using PbO-doped ZnO MSs/GCE were plotted against the applied potential to result the calibration of 2,6-DNP sensor expressed by ip(µA) = 1.0171C(µM) + 22.312 (R2 = 0.9951; regression co-efficient). The sensitivity of the proposed 2,6-DNP sensor probe obtained from the slope of the calibration curve as well as dynamic range for 2,6-DNP detection were found as 32.1867 µAµM−1cm−2 and 3.23~16.67 µM, respectively. Besides this, the lower limit of 2,6-DNP detection was calculated by using signal/noise (S/N = 3) ratio and found as good lowest limit (2.95 ± 0.15 µM). As known from the perspective of environment and healthcare sectors, the existence of phenol and their derivatives are significantly carcinogenic and harmful which released from various industrial sources. Therefore, it is urgently required to detect by electrochemical method with doped nanostructure materials. The reproducibility as well as stability of the working electrode duration, response-time, and the analysis of real environmental-samples by applying the recovery method were measured, and found outstanding results in this investigation. A new electrochemical research approach is familiarized to the development of chemical sensor probe by using nanostructured materials as an electron sensing substrate for the environmental safety (ecological system).

Fluorescent carbon quantum dots as a novel solution and paper strip-based dual sensor for the selective detection of Cr(VI) ions

Herein, we report the development of a simple green methodology to fabricate N-doped carbon quantum dots (N-CQDs) with a high luminescence using R. graveolens leaves following the hydrothermal method. Optical, chemical, morphological, and electrochemical properties were thoroughly investigated employing a variety of analytical techniques. The fabricated N-CQDs have a spherical shape, with an average diameter of 4.5 nm. Excitation dependent emission behaviour, 18% QY and green fluorescence were all observed in the N-CQDs. They are particularly resistant to various impacts such as ionic strength, pH, continuous visible light irradiation, and storage time. Since Cr(VI) ions are highly carcinogenic and mutagenic, there is an urgent demand for sensitive, selective, and efficient sensors for monitoring and measuring the amount of Cr(VI) ion in water in the environment. Hence, we developed the prepared N-CQDs as a label-free fluorescence and electrochemical probe for detecting Cr(VI) ions selectively and sensitively in aqueous solutions. Relying on static quenching together with the inner filter effect, N-CQDs performed exceptionally well as fluorescence sensors for Cr(VI) ions. The N-CQDs exhibit a limit of detection of 300 and 5 nM in the photoluminescence and differential pulse voltammetry analysis, respectively. The detection of Cr(VI) ions in real water samples using the developed sensor through both methods presented high precision without any interference. In addition, we also developed paper sensing strips for field application by depositing N-CQD on filter paper, which has been satisfactorily evaluated for sensing Cr(VI) in solid-state and solution mediums.

Carbamazepine degradation and genome sequencing of a novel exoelectrogen isolated from microbial fuel cells

Extracellular electron transfer and pharmaceutical products degradation mechanisms of electrochemical active microbial are helpful in optimizing electricity generation and biotoxic contaminants removal for microbial fuel cells (MFCs). An exoelectrogenic bacterial strain (designated as LYK-6) capable of degrading carbamazepine was first isolated from MFCs operated with carbamazepine as unique fuel. The strain LYK-6 was identified as the member of Pseudomonas genus according to morphological characteristics and 16S rRNA gene sequence analysis. Carbamazepine degradation rate of the strain LYK-6 was determined as 56.28% in inorganic salt medium using carbamazepine as sole carbon source. There were two oxidation peaks located at −0.044 V and 0.288 V revealed with differential pulse voltammetry analysis of the strain LQK-6. The maximum voltage of MFCs inoculated the strain LYK-6 reached to 187 mV when the MFCs fed with carbamazepine. The complete genome of the strain LYK-6 was of 4,454,672 bp in length and encoding 4209 protein genes. Genome annotation and functional gene analysis showed that the strain LYK-6 had significant genes encoding proteins responsible for the degradation of carbamazepine. The results demonstrated that the strain LYK-6 was promising application for the treatment of carbamazepine contaminant water by MFCs. This finding increases the known diversity of exoelectrogens.

Surfactant-Assisted Synthesis of Praseodymium Orthovanadate Nanofiber-Supported NiFe-Layered Double Hydroxide Bifunctional Catalyst: The Electrochemical Detection and Degradation of Diphenylamine.

Physiological storage disorders are caused by ineffective post-harvest handling of horticultural crops, particularly fruits. To address these post-harvest concerns, diphenylamine (DPAH•+) is widely used as a preservative to prevent fruit degradation and surface scald during storage around the world. Humans are negatively affected by the use of high concentrations of DPAH•+ because of the various health complications related to its exposure. As a result, accurate detection and quantification of DPAH•+ residues in treated fruits are critical. Rare earth metal orthovanadates, which have excellent physical and chemical properties, are potential materials for electrochemical sensors in this area. Herein, we present a simple and direct ultrasonication technique for the surfactant-assisted synthesis of praseodymium orthovanadate (PrVO4 or PrV) loaded on nickel iron layered double hydroxide (NiFe-LDH) synthesized with deep eutectic solvent assistance, as well as its application as an effective catalyst in the detection and degradation of DPAH•+ in fruits and water samples. The current work presents supreme electrochemical features of a PrV@NiFe-LDH-modified screen-printed carbon electrode (SPCE) where cetyltrimethylammonium bromide (CTAB) surfactant-driven fabrication of PrV directs the formation of highly qualified engineered structures and the deep eutectic solvent based green synthesis of NiFe-LDH creates hierarchical lamellar structures following the principles of green chemistry. PrV and NiFe-LDH combine to produce a synergistic effect that improves the number of active sites, charge transfer kinetics, and electronic conductivity. Differential pulse voltammetry analysis of PrV@NiFe-LDH/SPCE reveals a dynamic working range (0.005-226.26 μM), increased sensitivity (133.13 μA μM-1 cm-2), enhanced photocatalytic activity, and low detection limit (0.001 μM), which are considered significant when compared with the former reported electrodes in the literature for the determination of DPAḢ+ for its real-time applications.

Cobalt Oxide Nanorod-Modified GCE as Sensitive Electrodes for Simultaneous Detection of Hydroquinone and Catechol

An electrochemical sensor based on a cobalt oxide nanorod (Co3O4NR) modified glassy carbon electrode (GCE) (Co3O4NR-GCE) was prepared for simultaneous and selective determination of hydroquinone (HQ) and catechol (CT). Surface morphology and crystallinity of Co3O4NR were investigated employing field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The structure (16 nm) of the Co3O4 nanorod was observed in the FESEM image. A sharp peak pattern in the XRD survey revealed the following crystal planes in Co3O4NR material: (111), (220), (311), (222), (400), (422), (511), and (440). Electrochemical characterization of modified Co3O4NR-GCE was carried out performing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Selective and simultaneous detection of HQ and CT was carried out by performing CV and differential pulse voltammetry (DPV) analysis. In both studies, modified Co3O4NR-GCE showed well defined oxidation and reduction peaks for HQ and CT with enhanced peak current, and the oxidation peaks for HQ and CT were observed at 0.152 V and 0.254 V, respectively, in the CV analysis. Scan rate and pH variation analysis were performed to evaluate different kinetic parameters, including charge transfer coefficient (α = 0.56 for HQ and 0.66 for CT), heterogeneous charge transfer rate constant (ks = 56 for HQ and 72 for CT), and the number of electrons involved in HQ and CT oxidation. Quantitative analysis of HQ and CT was studied by observing the current response of DPV analysis with respect to concentration variation. Here, the detection limit was calculated as 0.2 µM for HQ with a linear concentration range of 5–200 µM, and 0.4 µM for CT with a linear concentration range of 5–150 µM. The practical applicability of the proposed sensor was investigated using sample solutions prepared in tap water. The reported sensor showed impressive selectivity towards HQ and CT in the presence of common interferents.

A precise electrochemical sensor based on Sm2O3/2D TiC hybrid for highly sensitive and selective detection of antihypertensive drug nimodipine

Hybridization of rare earth metal oxide with titanium carbide is a well-designed architecture for uses in sensing, energy conversion and storage, electronic devices, catalysis, and other applications. Herein to synthesized, a Sm2O3/2D TiC hybrid (samarium oxide/two-dimensional titanium carbide) using a facile hydrothermal process. The as-prepared hybrid was examined by various physicochemical techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HRTEM). From, the morphology study to confirm the Sm2O3 flakes were successfully hybridized with titanium carbide sheet as a result to enhance the electrochemical active sites, low resistivity, and rapid ion transportation. Due to this behavior the modified Sm2O3/2D TiC/GCE has successfully detected antihypertensive drug nimodipine (NMP) by using CV (cyclic voltammetry), and DPV (differential pulse voltammetry) analysis. The Sm2O3/2D TiC/GCE sensor has demonstrated high sensitivity (1.5 µA µM−1 cm−2), a low LOD (4.2 nM), excellent repeatability, reproducibility, and storage stability. Particularly, Sm2O3/2D TiC/GCE was effectively used to detect NMP in biological samples and to obtain a well-acceptable result. We believe that, this Sm2O3/2D TiC hybrid electrocatalyst can act as a potential electrode material for the electrochemical detection of NMP in clinical biological applications.

Comparative study of tetrasulfonated phthalocyanine modified screen-printed electrodes in paraquat

Emerging pollutants, including pesticides, have been an increasing problem to human and environmental health. Based on this, the development and optimization of sensors is an essential approach to controlling emerging pollutants. Here, screen-printed carbon electrodes (SPCE) modified with three MTsPc (FeTsPc, CuTsPc, or NiTsPc) were evaluated for voltammetric detection of paraquat (PQ). UV-Vis absorption and Raman spectroscopy coupled with optical microscopy were used to prove the metal center directly influences the aggregation of MTsPc on the electrode surfaces, which promotes variation on the redox couple of PQ. The adsorption of PQ2+ species was proportional to aggregation of MTsPc following the order FeTsPc > NiTsPc > CuTsPc. The FeTsPc/SPCE showed a better voltammetry response for PQ detection in both ultrapure and river water, being applied in sensing measurements. The differential pulse voltammetry analysis showed a linear range of 6.0–60 µmol/L with a limit of detection of 0.97 µmol/L in the standard sample and recovery of 103.3% in the river sample. The results indicate an excellent pertinence of sensing applications and the possibility of developing cheap devices.

Convenient Heme Nanorod Modified Electrode for Quercetin Sensing by Two Common Electrochemical Methods.

Quercetin (Qu) is one of the most abundant flavonoids in the human diet. High concentrations of Qu can easily cause adverse effects and induce inflammation, joint pain and stiffness. In this study, Heme was used as a sensitive element and deposited and formed nanorods on a glassy carbon electrode (GCE) for the detection of Qu. The Heme/GCE sensor was characterized using scanning electron microscopy (SEM), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the developed sensor presented a linear concentration ranging from 0.1 to 700 μmol·L−1 according to the CV and DPV methods. The detection limit for the sensor was 0.134 μmol·L−1 and its sensitivity was 0.12 μA·μM−1·cm−2, which were obtained from CV analysis. Through DPV analysis we obtained a detection limit of 0.063 μmol·L−1 and a sensitivity of 0.09 μA·μM−1·cm−2. Finally, this sensor was used to detect the Qu concentration in loquat leaf powder extract, with recovery between 98.55–102.89% and total R.S.D. lower than 3.70%. The constructed electrochemical sensor showed good anti-interference, repeatability and stability, indicating that it is also usable for the rapid detection of Qu in actual samples.

Electrochemically Activated Screen-Printed Carbon Electrode for Determination of Ibuprofen

In this study, we present a simple, sensitive and selective analytical procedure for the ibuprofen (IBP) analysis using the commercially available screen-printed carbon electrode electrochemically activated (aSPCE) by cyclic voltammetry in 0.1 M NaOH. The quantitative determinations of IBP were carried out in 0.25 M acetate buffer solution of pH 4.5 ± 0.1 using the differential-pulse voltammetry (DPV). Different experimental parameters for DPV analysis were optimized, including pH and concentration of supporting electrolyte, amplitude (ΔEA), scan rate (ν) and modulation time (tm). The linear ranges of calibration curve were from 0.50–20.0 and 20.0–500.0 µM. The detection and quantification limits were estimated to be 0.059 and 0.20 µM. The aSPCE displayed satisfactory repeatability, reproducibility, and selectivity. Furthermore, the DPV procedure with the use of aSPCE was used to determination of IBP in pharmaceutical formulations. The results achieved by DPV show satisfactory agreement with those obtained by manufacturers (the relative errors are in the range of 3.1–4.7%).

An efficient electrochemical sensing of hazardous catechol and hydroquinone at direct green 6 decorated carbon paste electrode

In this proposed work, direct green 6 (DG6) decorated carbon paste electrode (CPE) was fabricated for the efficient simultaneous and individual sensing of catechol (CA) and hydroquinone (HY). Electrochemical deeds of the CA and HY were carried out by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at poly-DG6-modfied carbon paste electrode (Po-DG6-MCPE). Using scanning electron microscopy (SEM) studied the surface property of unmodified CPE (UCPE) and Po-DG6-MCPE. The decorated sensor displayed admirable electrocatalytic performance with fine stability, reproducibility, selectivity, low limit of detection (LLOD) for HY (0.11 μM) and CC (0.09 μM) and sensor process was originated to be adsorption-controlled phenomena. The Po-DG6-MCPE sensor exhibits well separated two peaks for HY and CA in CV and DPV analysis with potential difference of 0.098 V. Subsequently, the sensor was practically applied for the analysis in tap water and it consistent in-between for CA 93.25–100.16% and for HY 97.25–99.87% respectively.

Samarium vanadate nanospheres integrated carbon nanofiber composite as an efficient electrocatalyst for antituberculosis drug detection in real samples

We have explored an electrochemical sensing platform based on samarium vanadate nanosphere embedded carbon nanofiber (SmVO4/CNF) for the determination of antituberculosis drug isoniazid (ISZ). The physicochemical properties were recognized, proving the well-aligned presence of SmVO4/CNF. The samples obtained were tested for electrochemical studies as electrochemical impedance spectroscopy (EIS), determining the lower resistance resulting in higher conductivity with Rct at 53 Ω. Prospective enhancement was observed for SmVO4/CNF/GCE with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) towards isoniazid electrochemical detection. The effective active surface area was calculated to be 0.155 cm−2 for SmVO4/CNF/GCE being two times larger than bare GCE with CV analysis. A lower detection limit of about 0.005 μM and a limit of quantification of about 0.0198 μM were significantly recognized with the linear range of about 0.09−800 μM as obtained by DPV analysis. Coexisting materials with ISZ had no interactions establishing excellent selectivity among interfering molecules. Biological and pharmaceutical samples exposed for real-time studies with an effective recovery range. Thus, collecting all these results will be a useful sensor being fabricated with SmVO4/CNF for synergetic detection of ISZ in real samples.

Nonenzymatic dopamine biosensor based on tannin nanocomposite

AbstractA dopamine (DA) biosensor was developed based on polypyrrole/tannin/cetyltrimethylammonium bromide (PPy/TA/CTAB) nanocomposite and central composite rotatable design (CCRD) was employed for the optimization of conditions. Chemical polymerization of the PPy/TA in the presence of a cationic surfactant, CTAB, reduced the particle size of composite and a rod‐like structure with a lumpy surface and high porosity was observed for nanocomposite justifying the highest current response for the modified electrode. Amperometry and differential pulse voltammetry analyses were applied for all electrochemical measurements and DA detection in the range of 0.5–100 μM. The good adhesion of nanocomposite on the electrode surface, as well as porosity and high surface area of the modified electrode, enhanced the diffusion of DA molecules inside the matrix. Amperometry analysis of the Screen printed carbon electrode/PPy/TA/CTAB modified electrode displayed a good sensitivity of 0.039 μA (μM)−1 toward DA with the limit of detection of 2.9 × 10–7 M. The modified biosensor also excludes the interfering species of ascorbic acid and uric acid which makes this sensor appropriate for DA determination. The proposed biosensor showed an acceptable reproducibility and repeatability with low relative standard deviations of 4.8% and 4.4%, respectively.

Preparation and Characterization of Au/NiPc/Anti-p53/BSA Electrode for Application as a p53 Antigen Sensor

While the tumor suppressor protein p53 regulates the cell cycle to prevent cell damage, it also triggers apoptosis and prevents cancer. These inhibitory functions may disappear once the p53 gene is mutated. Under these circumstances, the detection of p53 protein concentrations can have significant clinical applications. In this study, nickel phthalocyanine (NiPc) was coated on a gold electrode to produce a modified Au/NiPc electrode. p53 antibodies were bonded to the Au/NiPc electrode by the Ni+2 ion in NiPc, which can be self-assembled with the imidazole group of the p53 protein. The Au/NiPc/anti-p53 electrode was subsequently dripped with a buffer solution of bovine serum albumin (BSA) to form the Au/NiPc/anti-p53/BSA electrode, which was used for the detection of p53 antigen under 10 mM potassium ferricyanide/potassium ferrocyanide (K3Fe(CN)6/K4Fe(CN)6) solution by cyclic voltammetry and differential pulse voltammetry analyses. The linear detection range and the sensitivity for the p53 antigen were 0.1–500 pg/mL and 60.65 μA/Log (pg/mL)-cm2, respectively, with a detection time of 90–150 s. In addition, Au/NiPc/anti-p53 (100 ng/mL)/BSA electrodes were tested for specificity using glucose, bovine serum albumin, histidine, ascorbic acid, uric acid, prostate-specific antigen, human serum albumin, and human immunoglobulin G. All p-values were <0.0005, indicating an outstanding specificity.

Reduction Behavior of Olanzapine and Its Differential Pulse Voltammetric Determination in Human Urine and Pharmaceuticals

The electrochemical reduction behavior of olanzapine was investigated by DPV (differential pulse voltammetry) and CV (cyclic voltammetry) techniques using a glassy carbon electrode. The measurements were carried out in different buffer solutions in a pH range from 0.50 to 12.05. The behavior of the peak potential and the peak current were examined by changing the pH, and a pH= 7.0 Britton-Robinson buffer solution was selected as the supporting electrolyte. To designate the electron and proton numbers that participated in the reaction, the changing peak potentials of olanzapine with increasing pH were investigated. The number of transferred electrons was found equal to the number of the hydrogen ions taking part in the electrode reaction. Equal electron and proton numbers were also supported with suggested reduction mechanism. For DPV analysis, the linear calibration curve of olanza-pine was plotted between concentrations 2x10-5M and 1x10-4M at the pH= 7.0 Britton-Robinson buffer solution. The limit of detection (LOD) and the limit of quantification (LOQ) were found to be 1.88x10-6 M and 6.29x10-6M, respectively. Lastly, the developed technique was applied to spiked urine and pharmaceutical preparations for recovery studies of olanzapine. A reaction mechanism related to the reduction of olanzapine was also proposed with this study.

A simple and low-cost poly (dl-phenylalanine) modified carbon sensor for the improved electrochemical analysis of Riboflavin

The current study reports on the electroanalysis of Riboflavin (RF) on the surface of a poly dl -phenylalanine modified carbon paste sensor (PDLPAMCPS). The developed sensor caused a noticeable electrocatalytic action for the redox activity of RF in a phosphate buffer solution (PBS) of pH 6.5. This analysis was evaluated using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The active surface of the functioning sensor exposes well developed anodic peak with prominent electron transfer. PDLPAMCPS shows distinctive and improved DPV and CV peaks for RF with and without the presence of organic dyes and dopamine (DA). The impact of the solution pH, scan rate, accumulation potential and concentration on RF at PDLPAMCPS were studied. A vibrant linear growth was observed between the oxidation peak current and the RF concentration in the range of 6.0 μM–30.0 μM, which provides a lower limit of detection (LOD) of 92 nM with excellent sensitivity. The proposed method and sensor were applied for the assessment of RF in medicine sample as an analytical application with fine recoveries and low LOD. • A simple and low-cost carbon sensor was designed using poly ( dl -Phenylalanine) for the sensing of Riboflavin. • Prepared sensor was characterized by CV, DPV, EIS and FE-SEM analysis. • Equipped sensor shows high sensitivity, selectivity and lower LOD of 92 nM towards Riboflavin detection. • Interference effect on prepared sensor for Riboflavin was studied.

Electrochemical characterization of nanosurface-modified screen-printed electrodes by using a source measure unit

In this study, the performance of a source measure unit (SMU) performing cyclic and differential pulse voltammetry analyses, in comparison to potentiostat, is investigated. SMU is a versatile and accurate tool, capable of sourcing and measuring simultaneously and is comparable to the use of a potentiostat for such measurements. Here, two surface-functionalized screen-printed carbon electrodes with two different nanocomposites were utilized to represent the electrochemical system. The results unveil that the electrochemical behaviour of SMU is qualitatively comparable to that of the potentiostat with more than 97% accuracy; for both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Consequently, SMU is feasible for CV and DPV measurements.

A self-assembled electrochemical immunosensor for ultra-sensitive detection of ochratoxin A in medicinal and edible malt

Trace residue of mycotoxins in complex medicinal and edible food matrices has brought huge challenges for the development of ultrasensitive analytical methods. Here, a green electrochemical immunosensor for the ultrasensitive detection of ochratoxin A (OTA) was fabricated by self-assembling a compact 2-mercaptoacetic (TGA) monolayer on the surface of the working Au electrode to form the Au/TGA/bovine serum aibumin (BSA)-OTA/anti-OTA monoclonal antibody composite probes for selective and ultra-sensitive detection of OTA based on indirect competitive principle and differential pulse voltammetry analysis. The electrochemical impedance spectroscopy and cyclic voltammetry methods were introduced to characterize the assemble situation of the TGA-modified Au electrode and optimize some critical parameters for the green electrochemical immunoseonsor. Under the optimal conditions, the developed immunosensor exhibited much lower limit of detection (0.08 ng/mL) in the range of 0.1–1.0 ng/mL for OTA compared with other direct or disposable electrochemical immunosensors. Real application in the spiked malt samples verified high accuracy with no matrix interferences of the proposed immunoseonsor. This is a meaningful study on a self-assembled electrochemical immunoseonsor for ultra-sensitive and rapid detection of OTA in malt samples, which suggested a general simple-to-use sensing platform and prospect as an economical and green tool for ultra-sensitive detection of much more trace-level of toxic small molecules in other complex matrices to ensure their quality and safety.

The fabrication of a new modified pencil graphite electrode for the electrocatalytic reduction of 2-nitrophenol in water samples

In this study, we report a sensitive modified pencil graphite electrode prepared by easily coating with 3-amino-1,2,4-triazole-5-thiol (3AT5T) for the selective determination of 2-nitrophenol (2-NP) by differential pulse voltammetry (DPV) method. The electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), were applied to characterize this modified electrode in the mixture of K4[Fe(CN)6]/K3[Fe(CN)6] containing 0.1 M KCl as redox probe. Further, the electrode was characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). PGE demonstrated a remarkable increment in the redox probe's peak current, due to the effective electroactive surface area at the modified PGE (2.278 cm2) when it was compared with the bare PGE (0.128 cm2). This modified PGE was successfully used for the electrocatalytic reduction of 2-NP at pH 4.5 in 0.1 M phosphate (PBS) buffer. The reduction current response of 2-NP at the modified PGE was increased at about 8 times compared with the bare PGE. From the DPV analysis, under the optimized conditions, the reduction peak currents were increased linearly with two concentration intervals of 2-NP at pH 4.5 in PBS buffer. One of them is 45 nM–560 μM and the other is 560 μM–2 mM. The limit of detection (LOD) is found as 14.1 nM for 2-NP (S/N = 3). The fabricated PGE was tested in water samples for the practical utilization. From the results, it was pointed that the modified PGE can be used as an environmental sensor in analytical applications.

DPV-assisted understanding of TiO2 photocatalytic decomposition of aspirin by identifying the role of produced reactive species

A TiO2/UV photocatalytic process generates various reactive species via different oxidation and reduction routes and thus the contribution of such reactive species to the decomposition of organic chemicals in water has been unclear. In this study, decomposition of acetylsalicylic acid (ASA) as a probe was performed to find the specific role of charge carriers (ecb− and hvb+) and primary active species (such as O2−, OH, HO2, and H2O2). Differential pulse voltammetry (DPV) was introduced as an in-situ fast electrochemical method to identify produced intermediates. The study revealed that hydroxyl radicals (OH) produced by reduction of oxygen with ecb− and subsequent primary reactions (reduction pathway) play the major role in the photocatalytic decomposition of ASA, in comparison to direct oxidation of OH− or ASA by hvb+ (oxidation pathway). The in-situ DPV analysis probed that sequential OH addition to the ASA aromatic ring is the favorable oxidation mechanism.