Surface Of Graphite Electrode Research Articles

Investigation of a novel ceramic coating for graphite electrodes in electric ARC furnaces using numerical simulation, experimental method, and industrial testing

Electric ARC furnaces (EAF) are referred to as a set of furnaces in which the process of melting metal materials takes place using an electric ARC. The temperature of melting and discharging in these furnaces is different and can vary between 1600 and 3000 ℃. These furnaces can use lime, fluorine, iron, etc., and ferroalloys to produce metal products such as steel or cast iron. The production of EAF metal products depends on various factors, including graphite electrodes. Electric electrodes are one of the main components of EAF, which transfer the current by creating an electric ARC from the electrode arms to the furnace load. Nowadays, a growing need is felt for using graphite electrodes in electric ARC furnaces (EAF). The validity of SiO2/ TiO2 productive coating is evaluated to decrease the corrosion resistance of graphite electrodes through the experiments. The corrosion of the graphite samples was simulated using finite element (FE) simulation in ANSYS software. FE simulation was used to model the actual working condition of electrodes in the EAF. The validity of SiO2/TiO2 productive coating is evaluated to decrease the corrosion of electrodes by using numerical simulation, experimental methods, and industrial testing in the EAF. All the tests and experiments performed in this study were to obtain a more precise consideration of the corrosion of electrodes. Also, using the TGA (Thermo-gravimetric analysis), the results show that this ceramic coating has a prominent role in decreasing the corrosion of electrodes at high temperatures. Finally, it was realized that coating the surface of graphite electrode with two layers of SiO2/ TiO2 would effectively decrease the consumption of graphite electrodes.

Coordinated molecularly imprinted-based ratiometric sensor for electrochemical sensing of hazardous ciprofloxacin based on nitrogen and sulfur co-doped porous carbon/silver nanoparticles hybrid

A highly responsive and selective coordinated molecularly imprinted polymer (MIP)-dependent ratiometric electrochemical platform for ciprofloxacin (CIPX) detection was developed. It consists of porous carbon modified with heteroatoms (N, S@C) built on pencil graphite electrode (PGE) surface. The N, S@C/PGE was then modified using silver nanoparticles (AgNPs), which were employed to boost conductivity and surface area of the electrode, as well as an internal reference signal. Molecularly imprinted film was built on AgNPS/N, S@C/PGE surface in the existence of template (CIPX) via electro-deposition of Cu (II)-coordinated pyrrole-3-carboxylic acid. The detection of CIPX is based on the measurement of ICIPX/IAgNPs ratios using differential pulse voltammetry (DPV), which were linearly proportional to CIPX concentration in the range of 0.13–650 nM with LOD (S/N = 3) of 38 pM. The as-fabricated coordinated MIP-dependent ratiometric electrochemical platform exhibited many advantages including low detection limit, long-term stability, detection reliability, and good reproducibility/selectivity. The electrochemical probe was efficiently used for the analysis of CIPX-containing specimens with recoveries % in the range of 97.6–101.6 % with RSDs % in the range of 2.6–3.2 %, proving accuracy of the platform.

Polypyrrole/carbon dot nanocomposite as an electrochemical biosensor for liquid biopsy analysis of tryptophan in the human serum of normal and breast cancer women

Liquid biopsy analysis represents a suitable alternative analysis procedure in several cases where no tumor tissue is available or in poor patient conditions. Amino acids can play a crucial role in aiding cancer diagnosis. Monitoring of tryptophan (Trp) catabolism can aid in tracking cancer progression. Therefore, a novel nanocomposite was fabricated using overoxidized polypyrrole film doped with nano-carbon dots (nano-CDs) on the pencil graphite electrode (PGE) surface for sensitive evaluation of Trp in human serum. Using square wave voltammetry (SWV), the overoxidized polypyrrole/carbon dots/pencil graphite electrode (Ov-Ox PPy/CDs/PGE) achieved excellent electrochemical catalytic activity for evaluating Trp. The modified electrode, known as Ov-Ox PPy/CDs/PGE, demonstrated superior electrochemical catalytic activity compared to bare PGE, CDs/PGE, PPy/PGE, and PPy/CDs/PGE for evaluation of Trp. The method’s excellent sensitivity was confirmed by the low limits of detection (LOD = 0.003 μmol L−1) and limit of quantitation (LOQ = 0.009 μmol L−1). The biosensor that was developed can measure tryptophan (Trp) levels in the serum of both healthy individuals and female breast cancer patients with high accuracy and sensitivity. The results indicate that there is a significant difference, as shown by the F-test, between healthy individuals and those with breast cancer. This suggests that Trp amino acid could be an essential biomarker for cancer diagnosis. Consequently, liquid biopsy analysis presents a valuable opportunity for early disease detection, particularly for cancer.Graphical abstract

Insights into the Interaction of Dacarbazine and Human Serum Albumin from Electrochemical Probing

The interaction between dacarbazine (DAC) and human serum albumin (HSA) was investigated under physiological conditions using electrochemical techniques, including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The CV results demonstrated that the oxidation of DAC on a pyrolytic graphite electrode (PGE) surface was irreversible and controlled by an adsorption-diffusion process. The addition of HSA was found to decrease the peak potential of DAC without altering the electrochemical parameters, which is likely due to the formation of an electro-inactive complex between the drug and protein, as supported by DPV and EIS measurements. Using DPV, the binding constant and stoichiometry of the complex were calculated to be 2.16 × 104 mol−1 l and 1:1, respectively. The temperature effect revealed that DAC binds to HSA through hydrophobic forces. In addition, the PGE electrode was successfully used to determine DAC in from biological samples.

A novel electrochemical biosensor based on palladium nanoparticles decorated on reduced graphene oxide-polyaminophenol matrix for the detection and discrimination of mitomycin C-DNA and acyclovir-DNA interaction

Both the design of molecules that will interact specifically with DNA and the determination of the mechanism of action of this drug on DNA are important as they allow the control of gene expression. In particular, rapid and precise analysis of this type of interaction is a vital element for pharmaceutical studies. In the present study, a novel reduced graphene oxide/ palladium nanoparticles/ poly(2-amino-4-chlorophenol) (rGO/Pd@PACP) nanocomposite was synthesized by chemical process to modify pencil graphite electrode (PGE) surface. Here, the performance of the newly developed nanomaterial-based biosensor for drug-DNA interaction analysis has been demonstrated. For this purpose, it was determined whether this system, which was developed by selecting a drug molecule (Mitomycin C; MC) known to interact with DNA and a drug molecule (Acyclovir; ACY) that does not interact with DNA, performs a reliable/accurate analysis. Here, ACY was used as a negative control. Compared to bare PGE, the rGO/Pd@PACP nanomaterial modified sensor exhibited 17 times higher sensitivity performance in terms of guanine oxidation signal measured by differential pulse voltammetry (DPV). Moreover, the developed nanobiosensor system provided a highly specific determination between the anticancer drug MC and ACY by discrimination the interactions of these drugs with double-stranded DNA (dsDNA). ACY was also preferred in studies for the optimization of the new nanobiosensor developed. ACY was detected in a concentration as low as 0.0513 μM (51.3 nM) (LOD), and limit of quantification (LOQ) was 0.1711 μM with a linear range from 0.1 to 0.5 μM.

Ratiometric sensing interface for glutathione determination based on electro-polymerized copper-coordinated molecularly imprinted layer supported on silver/porous carbon hybrid

A novel molecularly imprinted ratiometric-based sensor was designed for highly selective and ultrasensitive electrochemical detection of glutathione (GSH). The sensor consists of porous carbon co-doped with nitrogen and sulfur formed on the surface of graphite electrode (N, S@PC/GE). Silver nanoparticles (Ag) were grown on the surface of N, S@PC/GE to improve the conductivity/surface area of the sensor and represent an internal reference signal for ratiometric response. The monomer (pyrrole-4-carboxylic acid, Py-COOH) was electro-polymerized on the surface of Ag/N, S@PC/GE in the presence of Cu (II) to form Cu-MIP@Ag/N, S@PC/GE. Addition of GSH decreased the signal of Ag at 0.18 V (oxidation of Ag) due to coordination complexation, while the signal response at 0.83 V (oxidation of Ag-GSH complex) was increased. Under optimum conditions, the ratio response (IGSH/IAg) was increased with increasing the concentration of GSH in the range of 0.01–500 nM with a detection limit (S/N = 3) of 0.003 nM. The electrochemical sensor exhibits many advantages including low LOD, high selectivity, good reproducibility, and satisfactory stability. The sensor was successfully applied to determine GSH in dietary supplements and human serum samples with recoveries % ranged from 97.4 to 101.8% and relative standard deviation % (RSD %) did not exceed 3.8%. This research paper introduces new information for the construction of molecular imprinted ratiometric-based electrochemical sensors for highly selective and sensitive detection of (bio) molecules.

Anhydride type film-forming electrolyte additives for high-temperature LiNi0.6Co0.2Mn0.2O2//graphite pouch cells

LiNi0.6Co0.2Mn0.2O2//graphite full cell, due to its high energy density as the most promising candidate for power batteries received increased attention, but the severe capacity loss under high-temperature conditions prevents their large-scale application. Here, glutaric anhydride (GA) and succinic anhydride (SA) as electrolyte additives are investigated to overcome the high-temperature problem of LiNi0.6Co0.2Mn0.2O2//graphite cells. Due to the unique film-forming features and high-temperature stability, the cells containing 0.5% GA and 0.5% SA can retain capacity retention of 91.2% and 92.4% stored at 60 ​°C for 15 days, corresponding to a negligible capacity loss of 4.6 and 0.8 mAh g-1 after 200 cycles, respectively. In addition, the lifespans of cells under 25 ​°C are also significantly extended by introducing GA and SA into the electrolytes. Electrochemical and spectroscopic techniques results indicate the full cell capacity loss is predominantly caused by the unstable anode solid electrolyte interphase (SEI) layer and a stable SEI film derived from GA and SA is formed on the graphite electrode surfaces. The SEI film can effectively inhibit the consumption of electrolytes and enhance the high-temperature performance of cells. This work paves a way for moderating high energy density cells' work under high-temperature operation by developing special anodic film-forming electrolyte additives.

Anti-Kanser İlaç Vinblastin’in Kalem Grafit Elektrot Yüzeyinde Elektrokimyasal Özelliklerinin İncelenmesi Ve Miktar Tayini

Kanser kemoterapisinde kullanılan vinblastin (VNB) antineoplastik bir ilaçtır. Sunulan bu çalışmada, VNB‘nin elektrokimyasal özellikleri tek kullanımlık kalem grafit (PG) elektrot ile geniş bir pH aralığında ve farklı destek elektrolitler ‘’Britton–Robinson (0.04 M BR, pH 2.0-12.0), fosfat (0.04 M PBS, pH 2.0, 3.0, 4.0, 7.4) ve asetat ( 0.04 M ABS, pH 4.8) içinde döngüsel voltametri ‘’CV’’ ve Kare Dalga Voltametri ‘’SWV’’ teknikleriyle incelenmiştir. VNB, +0.993 V gerilim ve 3.844 µA akım değerinde BR (pH 2.0) içinde CV ile tersinmez bir yükseltgenme piki vermiştir. SWV tekniği ile anodik akım sinyali, BR (pH 2.0) içerisinde 11 nM ile 495 nM arasında derişim ile doğrusal bir korelasyon gösterdi ‘’Ip (µA) = 0.0087 C (nM) - 0.3448 (r = 0.993, n = 12)’’ . 11 nM derişim seviyesinde, 2.4 nM gözlenebilme sınırı (LOD) ve % 2.93 göreli standart sapma hesaplandı. Önerilen yöntemin analitik uygulaması ilaç ve idrar örneklerinde pratik edilmiş ve geri kazanımlarla gösterilmiştir.

Voltammetric and In Situ Spectroscopic Investigations on the Redox Processes of Trioxotriangulene Neutral Radicals on Graphite Electrodes

To investigate the microscopic electrochemical dynamics of a stable trioxotriangulene (TOT) organic neutral π-radical on a graphite electrode surface, voltammetric and in situ infrared (IR) spectroelectrochemical studies were conducted using electrolyte solutions containing TOT monoanions. Upright columnar crystals (face-on alignment) of the TOT neutral radical were preferentially formed and dissolved in a rather reversible manner in the electrolyte with a low concentration of TOT monoanion under electrochemical conditions; however, more flat-lying columnar crystals (edge-on alignment) were formed in a higher concentration electrolyte. The flat-lying crystals remained on the graphite surface even at a fully reduced potential, owing to the lack of direct π-π interactions between the molecules and the graphite electrode. In situ IR attenuated total reflectance spectroscopy analyses successfully characterized the alignment of the columnar crystals of the TOT neutral radicals and their electrochemical behaviors, including the possible origins of the irreversible redox reaction of TOT on the graphite electrode.

Development of a Disposable Aptasensor Using Carboxymethyl Cellulose and Hydroxyapatite Nanoparticles for Voltammetric Detection of Glyphosate

The development of monitoring tools for the detection of glyphosate is an attractive topic since its consumption is one of the debated worldwide issue. Herein, a bionanocomposite modified disposable electrochemical biosensor platform was developed for sensitive and selective detection of glyphosate. For this purpose, carboxymethyl cellulose (CMC) and hydroxyapatite nanoparticles (HaNP) were modified at the surface of disposable pencil graphite electrodes (PGEs). After the fabrication of CMC/HaNP-PGEs, glyphosate specific DNA aptamer that had G-quadruplex structure was immobilized at the surface of CMC/HaNP-PGEs. The specific interaction between DNA aptamer and glyphosate was performed at the electrode surface. Before/after each modification/immobilization/interaction step, anodic current value obtained by cyclic voltammetry measurements performed in 2.00 mM K3[Fe(CN)6]/K4[Fe(CN)6] (1:1) and 0.10 M KCl was recorded, and the changes at the average anodic current values were evaluated in terms of the optimization of experimental parameters. The limit of detection and limit of quantification values were calculated as 0.04 and 0.13 μg ml−1, respectively. The selectivity of the developed aptasensor was tested against 2,4-dichlorophenoxyacetic acid, glufosinate, and (aminomethyl) phosphonic acid. The applicability of the aptasensor was shown using water samples. This novel aptasensor platform is a prototype for future hand-held devices developed for GLY monitoring.

Application of a new electrochemical sensor for voltammetric determination of p-nitrophenol and betulin

A highly sensitive electrochemical sensor based on a Surface Active Modifier (SAM) consisting of Taunit-M carbon nanotubes and mesoporous carbon (NanoTechCenter LLC, Tambov, Russia) is developed for the voltammetric determination of betulin and p-nitrophenol. The effect of the modifier concentration on the electrode surface on the analytical signal of betulin was studied, and a method for modifying the surface of the SAM graphite electrode was developed. The developed method is easy to use, fast, stable, sensitive, and cost-effective procedure, which can be used to detect these analytes in real samples. Voltammograms of p-nitrophenol were obtained for the first time on the developed modified electrochemical sensor and the dependence of the height of its analytical signal on the pH of a phosphate buffer thus obtained was studied in a wide pH range from 4 to 12, a background electrolyte with optimal pH was also chosen. Proceeding from the calibration dependences of the height of the betulin analytical signal on the concentration obtained for various background electrolytes with different pH and cation-anion composition, a background electrolyte with the maximum sensitivity of the analytical signal was selected on a modified electrochemical sensor. Study of cyclic voltammograms was carried out to understand the electrode processes, exhibiting a pronounced peak of anodic oxidation observed in a potential range from 0.7 to 0.9 V. However, there was no peak in the cathodic direction which indicates the irreversible nature of the electrode process. When determining the nature of currents, the Semerano criterion equal to 1.6 was calculated, which indicates the absence of the contribution of the diffusion component of the current. Verification of the correctness of the voltammetric method for determining betulin on a new electrochemical sensor was carried out using the «spike-test» method. The data obtained show that the voltammetric determination of betulin can be carried out with a measurement error not exceeding 15%. The proposed modified electrodes were compared with previously known electrodes for the determination of pentacyclic triterpenoids and pesticides at concentrations of 0.5 × 10–3 – 8.0 × 10–3 mg/dm3.

Carbon nanotubes – PEI – Formate dehydrogenase nano-biointerface for the specific bioelectrochemical reduction of CO2 to formate

Reduction of extensive CO2 emissions is one of the key challenges that our society must overcome in order to minimize the effects of global warming and climate change. In this respect, electrochemical reduction of CO2 via redox enzymes is believed to be a promising route to minimize global CO2 concentrations, as they specifically catalyze the selective CO2 reduction in a reversible way at low potentials and mild conditions. In this work, we describe the effective anchoring of the enzyme Desulfovibrio vulgaris Hildenborough FdhAB formate dehydrogenase using electrostatic interactions favoring oriented immobilization, to the surface of MWCNTs-modified low density graphite electrodes with subsequent protection of the enzyme with polyethyleneimine (PEI) polymer. The synergistic effect of MWCNTs and PEI has been studied. High catalytic current densities, up to −230 μA cm−2, as well as a high operational stability of 11 h of continuous long-term measurements, were achieved.

Fully optimized new sensitive electrochemical device for the selective determination of 6-thioguanine anticancer drug in wastewater and biological samples

In present work, a novel voltammetric sensor for the determination of 6-thioguanine (6-TG) was fabricated. First, a graphite rod electrode (GRE) surface was modified via drop-coating of graphene oxide (GO) to increase the surface area of the electrode. Subsequently, molecularly imprinted polymer (MIP) network was prepared using a facile electro-polymerization procedure, using o-aminophenol (as functional monomer) and 6-TG (as template molecule). Influences of test solution pH, dropped GO concentration and incubation time on the performance of GRE-GO/MIP were studied, and their values determined as 7.0, 1.0 mg/mL and 90 s, respectively. Using GRE-GO/MIP, 6-TG was measured in the range of 0.5–60 μM with a low detection limit (DL) of 80 nM (based on S/N = 3). In addition, the electrochemical device demonstrated good reproducibility (3.8%) and anti-interference ability toward 6-TG monitoring. The as-prepared sensor illustrated satisfactory sensing performance in real samples with recovery ranging from 96.5% to 102.5%. For the determination of trace amounts of anticancer drug (6-TG) in real matrices (biological samples and pharmaceutical wastewater sample), this study is expected to provide an effective strategy with high selectivity, stability, and sensitivity.

Fabrication of a Disposable Amperometric Sensor for the Determination of Nitrite in Food.

Silver nanoparticles (AgNPs) were synthesized through an environmentally friendly method with tea extract as a reduction agent. By immobilizing them on the surface of a low-cost pencil graphite electrode (PGE) with the aid of a simple and well-controlled in-situ electropolymerization method, a novel nanosensing interface for nitrite was constructed. The film-modified PGE showed good electrocatalytic effects on the oxidation of nitrite and was characterized through scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. Characterization results clearly show that the successful modification of AgNPs improved the surface area and conductivity of PGEs, which is beneficial to the high sensitivity and short response time of the nitrite sensor. Under the optimal detection conditions, the oxidation peak current of nitrite had a good linear relationship with its concentration in the range of 0.02-1160 μmol/L with a detection limit of 4 nmol/L and a response time of 2 s. Moreover, the sensor had high sensitivity, a wide linear range, a good anti-interference capability, and stability and reproducibility. Additionally, it can be used for the determination of nitrite in food.

Simultaneous Voltammetric Determination of Epinine and Venlafaxine Using Disposable Screen-Printed Graphite Electrode Modified by Bimetallic Ni-Co-Metal–Organic-Framework Nanosheets

We constructed two-dimensional NiCo-metal-organic-framework (NiCo-MOF) nanosheets based on a facile protocol and then characterized them using multiple approaches (X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission-scanning electron microscopy (FE-SEM), and N2 adsorption/desorption isotherms techniques). As a sensitive electroactive material, the as-fabricated bimetallic NiCo-MOF nanosheets were employed to modify a screen-printed graphite electrode surface (NiCo-MOF/SPGE) for epinine electro-oxidation. According to the findings, there was a great improvement in the current responses of the epinine because of the appreciable electron transfer reaction and catalytic performance of the as-produced NiCo-MOF nanosheets. Differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry were utilized to analyze the electrochemical activity of the epinine on the NiCo-MOF/SPGE. A linear calibration plot was obtained in the broad concentration range (0.07-335.0 µM) with a high sensitivity (0.1173 µA/µM) and a commendable correlation coefficient (0.9997). The limit of detection (S/N = 3) was estimated at 0.02 µM for the epinine. According to findings from DPV, the electrochemical sensor of the NiCo-MOF/SPGE could co-detect epinine and venlafaxine. The repeatability, reproducibility and stability of the NiCo-metal-organic-framework-nanosheets-modified electrode were investigated, and the relative standard deviations obtained indicated that the NiCo-MOF/SPGE had superior repeatability, reproducibility and stability. The as-constructed sensor was successfully applicable in sensing the study analytes in real specimens.

Direct electrochemical detection of extracellular nitric oxide in Arabidopsis protoplast based on cytochrome P450 55B1 biosensor

Cytochrome P450 55B1(CYP55B1) from Chlamydomonas reinhardtii reduces nitric oxide (NO) to dinitrogen oxide (N2O) with the electron supply from NAD(P)H in vivo. Here a novel nitric oxide biosensor was developed by immobilized CYP55B1 on the surface of pyrolytic graphite electrode (PGE) by cross-linking with glutaraldehyde (GA) and bovine serum albumin (BSA). The direct electrochemistry of CYP55B1 was realized with the redox peak potential of −0.355 V and −0.385 V and the catalytic reduction peak of NO by CYP55B1 is at −0.85 V at the scan rate of 0.5 V S−1 in pH 7.0 phosphate buffer. The apparent coverage (Γ = 1.43 × 10−11 mol cm−2), the electron transfer rate constant (ks = 17.39 s−1) and apparent affinity to NO (Kmapp = 11.64 nM) of CYP55B1 in GA/BSA film were obtained. The catalytic mechanism of CYP55B1 towards NO with NADH was examined by the biosensor. The linear range of NO detection was investigated by differential pulse voltammetry with the results of 5–50 nM and the detection limit of 0.5 nM (S/N = 3). The selectivity and stability of the electrochemical biosensor were investigated. Furthermore, the CYP55B1electrochemical biosensor was applied to monitor NO release from Arabidopsis protoplasts with the average content of 0.848 fmol per cell under anaerobic condition.

Zip Nucleic Acid-Based Genomagnetic Assay for Electrochemical Detection of microRNA-34a.

Zip nucleic acid (ZNA)-based genomagnetic assay was developed herein for the electrochemical detection of microRNA-34a (miR-34a), which is related to neurological disorders and cancer. The hybridization between the ZNA probe and miR-34a target was performed in the solution phase; then, the resultant hybrids were immobilized onto the surface of magnetic beads (MBs). After magnetic separation, the hybrids were separated from the surface of MBs and then immobilized on the surface of pencil graphite electrodes (PGEs). In the case of a full-match hybridization, the guanine oxidation signal was measured via the differential pulse voltammetry (DPV) technique. All the experimental parameters that influenced the hybridization efficiency (i.e., hybridization strategy, probe concentration, hybridization temperature, etc.) were optimized. The cross-selectivity of the genomagnetic assay was tested against two different miRNAs, miR-155 and miR-181b, individually as well as in mixture samples. To show the applicability of the ZNA-based genomagnetic assay for miR-34a detection in real samples, a batch of experiments was carried out in this study by using the total RNA samples isolated from the human hepatocellular carcinoma cell line (HUH-7).

HER2 targeted noninvasive immunosensor based on pencil graphite electrode for detection of breast cancer

In the current research, we have fabricated an amperometric immunosensor for the detection of breast cancer using HER2 antibody. The sensor was fabricated by immobilization of anti-HER2 antibody on the surface of pencil graphite electrode (PGE). The techniques used for the characterization of the PGE/anti-HER2 were cyclic voltammetry, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The sensor was optimized in terms of pH, temperature, antigen concentration, response time and antibody concentration. A linear range amidst 1 fgml−1 and 20 ngml−1 was observed. The limit of detection was 1 ​fg/ml. HER2 levels were also determined in sera samples of apparently healthy persons and breast cancer patients. The authentication of the fabricated immunosensor was noticeable due to its good regeneration ability and storage stability.

Voltammetric investigations of functional dyspepsia drug acotiamide at pencil graphite electrode: An eco-friendly and cost effective stripping detection method

First time, the electro-oxidative behaviour and determination of acotiamide at a pencil graphite electrode have been investigated under different experimental conditions using cyclic voltammetry (CV), differential pulse anodic stripping voltammetry (DPASV), and square wave anodic stripping voltammetric (SWASV) techniques. The voltammetric responses of acotiamide have been analyzed at different scan rates, pH and concentrations. Oxidation of acotiamide at the surface of pencil graphite electrode gave two well defined irreversible peaks in the voltammograms in BR buffer of pH 7.0. The oxidation process is completely diffusion controlled. A linear response of peak current has been obtained between 15.5 to 124 μM in non-aqueous media for all the voltammetric techniques. The proposed DPASV and SWASV techniques show limit of detection at 18.58 and 13.36 μM, respectively.

A novel mesna-based electrochemical sensor embellished with silver nanoparticles for ultrasensitive analysis of modafinil.

Modafinil (MOD) is a CNS stimulant used for the treatment of narcolepsy, shift work sleep disorder, excessive daytime sleepiness, and post-COVID 19 neurological symptoms. In the literature, there is no report of square wave voltammetric (SWV) methods being used for the determination of MOD. This study describes, for the first time, the construction and evaluation of the analytical performance of a novel sensor for ultrasensitive SWV detection of MOD. The sensor was constructed by integration of silver nanoparticles (AgNPs) on Mesna (MSN) layers over a pencil graphite electrode (PGE) surface. The interface and morphological characteristics of the fabricated AgNPs@MSN/PGE sensor were investigated via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). This sensor was found to enhance the electro-oxidation of MOD. The combination of AgNPs@MSN/PGE with SWV enabled the determination of MOD in its bulk form and in pharmaceutical and biological matrices at the nanomolar scale (LOD = 28.59 nM) with excellent recoveries. This study represents the first report describing an electrochemical procedure for MOD detection in human plasma. The established SWV method was also validated, and the results were consistent with ICH criteria. Finally, the presented SWV procedure provides a facile, sensitive, rapid, and cost-effective approach compared to other existing methods.