Disposable Pencil Graphite Electrode Research Articles

Development of a chitosan-gold nanocomposite based disposable pencil graphite electrode for the selective detection of thiram in peach juice

ABSTRACT Hazardous chemicals that are mostly employed in modern agriculture for pest management have caused long-term environmental accumulation as well as major issues with food safety and human health. So, there is an urgent demand for efficient detection methods for environmental monitoring. To do this, the most contemporary electrochemical sensor technology is suggested. In this study, a new electrochemical sensor has been developed to detect thiram (Th) fungicide, utilising a modified activated pencil graphite electrode (a-PGE) made from chitosan-gold nanoparticle polymer (Ch-AuNPs) for the first time. The Ch-AuNPs/a-PGE surface has been characterised using cyclic voltammetry (CV), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Following adjustments to experimental parameters, the proposed electrochemical sensor demonstrated a linear calibration curve within the range of 4.90–140 μM, displaying a rapid response to thiram with a detection limit of 1.15 μM. The sensor exhibited notable selectivity, stability, and reproducibility. To assess its practical utility, the sensor was applied to analyse thiram in peach juice, and the recovery process indicated its effectiveness as a practical, swift, and efficient tool in pesticide residue monitoring.

First electrochemical investigation and determination of non-steroidal anti-inflammatory drug etofenamate using disposable pencil graphite electrode with voltammetric techniques

In this study, the electrochemical properties of etofenamate, an active ingredient belonging to the non-steroidal anti-inflammatory drug group, were investigated using cyclic voltammetry (CV) and square wave voltammetry (SW) techniques on a disposable pencil graphite electrode (PGE). With the CV technique, reversible voltammetric waves of around +0.470 V and irreversible voltammetric waves of around +1.02 V were produced on the PGE. An environmentally friendly, selective and highly sensitive SW voltammetric method was developed using disposable PGE. This voltammetric method gave very good analytical working range on PGE in PBS (pH = 3.0) medium at concentrations ranging from 0.017 μM to 0.306 μM. The LOD value of this analytical method in PBS (pH = 3.0) medium was calculated as 0.0011 μM (0.406 μg L−1). The developed voltammetric method was successfully applied to urine and drug samples. The results of the voltammetric method were compared with the results of the spectrophotometric method. The results were found to be compatible with each other.

Application of eco‐friendly disposable pencil graphite sensor for electrochemical evaluation and determination of podophyllotoxin using in cancer treatment

AbstractA sensitive, simple and selective voltammetric method was developed for the quantification of plant‐derived podophyllotoxin, which is included in antineoplastic drugs, using a disposable pencil graphite electrode. Using the square‐wave voltammetry technique, podophyllotoxin gave a very good voltammetric response at +1.24 V (vs. Ag/AgCl) potential (at 0.0 V and after 60 s pre‐concentration) in Britton Robinson (pH 4.0) media. This procedure was used to detection the compound in the concentration range of 12.4–299.5 nM with a limit of detection to 2.62 nM (1.08 μg L−1). The proposed method has been successfully applied to human urine samples.

Cost‐Effective Cholesterol Monitoring by Enzyme‐Based Electrochemical Assay

AbstractHerein we present a practical, disposable, enzyme‐based electrochemical biosensor to revolutionize a rapid and precise measurement of cholesterol level in saliva. To create a biosensor that can measure cholesterol levels, cholesterol oxidase (ChOx) was immobilized on disposable pencil graphite electrode (PGE) via EDC/NHS chemistry. This ChOx‐PGE biosensor has been characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS). Various critical experimental parameters, including nafion concentration, enzyme concentration, enzyme‐cholesterol interaction time, were optimized ensuring consistency and precision in our results and maintained constant throughout the experiments. Under optimum conditions, the detection limit was found to be 62 μM and the sensitivity of the sensor was calculated as 1112.8 Ohm mM−1 cm−2. The potential interferences such as glucose, ascorbic acid, uric acid, cysteine was selected to test the selectivity and no significant response was observed. Finally, the proposed biosensor was effectively employed to measure cholesterol level in saliva. This biosensor boasts a rapid response time of just 20 minutes and achieves a remarkable detection limit of 95 μM for salivary cholesterol, surpassing existing techniques. Our assay not only offers an innovative solution for cholesterol monitoring but also opens new horizons in point‐of‐care diagnostics with its disposable and practical design.

Novel Determination of the Influence of Idarubicin upon DNA Chain Structure Using an Electrochemical DNA Biosensor by Voltammetry

Two sequences of DNA (single-strand DNA (ssDNA) and double-strand DNA (dsDNA)) modified disposable electrodes were designed to investigate the effect of antitumor agent drug idarubicine (IDA) on the DNA chain structure. The effect of IDA on DNA structure was analyzed by square wave voltammetry (SWV) depending on not only the guanine signal but also IDA oxidation response. The present study included the electrochemical investigation of IDA and the investigation of the biomolecular interaction between IDA and DNA. IDA was detected in buffer and urine using disposable pencil graphite electrodes (PGE) with SWV and cyclic voltammetry (CV)). The detection limit (LOD) of IDA in urine samples was 0.089 µg mL−1 with SWV under optimum conditions. For the biomolecular interaction of IDA and DNA, all electrochemical conditions, such as the concentration of DNA, concentration of IDA, interaction phase (at electrode surface/in solution phase), the interaction pH, and the interaction time were optimized. IDA interacted biomolecularly with DNA at the electrode surface and in solution phase using two methods. There is no previous electrochemical study performed on the interaction of IDA with ssDNA. Hence, the effect of IDA on both ssDNA and dsDNA was presented for the first time.

Amine-Functionalized Pencil Graphite Electrode for Simultaneous Determination of Dopamine and Uric Acid

In this study, an electrochemical transducer based on an Amine-functionalized cheap and disposable pencil graphite electrode (NPGE) is proposed for the simultaneous monitoring of Dopamine (DA) and Uric Acid (UA) in biological samples such as serum and urine. The prepared NPGE was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that the incorporation of amine groups significantly improved catalytic activity than the bare pencil graphite electrode (BPGE). Moreover, the electrode modification parameters and effects of different analytical variables such as sweep rate, pH of the supporting electrolyte solution, and possible interfering ions or molecules in quantification were optimized using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimized conditions, DA and UA oxidation currents showed linear responses over the concentration range of 1.06-160 µM for DA and 30.06-150 µM for UA. The limit of detection (LOD) for DA and UA were estimated to be 0.94 and 1.26 µM, respectively. In addition, the transducer’s sensitivity of 5.47 µA.µM-1cm-2 for DA and 1.70 µA.µM-1cm-2 for UA were calculated. Aiming to reuse the transducer, a regeneration solution is proposed which could successfully remove the adsorbed oxidized products from the surface. Finally, the developed transducer’s performance was compared with the established clinical method. Figure 1

Disposable Pencil Lead as an Electrochemical Transducer for Monitoring Catechol in River and Tap Water

A cheap and disposable pencil graphite electrode (PGE) was developed by the incorporation of amine groups (Am-PGE-1). A further improvement in the performance was observed when the aminated electrode (Am-PGE-1) was activated by applying a negative potential scan (Am-PGE-2). The electrochemical transport properties were evaluated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The Nyquist plot showed a reduced charge transfer resistance value of 24.3 Ω for Am-PGE-2, while it was 95.1 Ω for bare PGE. Thus, Am-PGE-2 was used as a sensing platform for the detection of catechol. It was found that the electrochemical response of catechol oxidation at Am-PGE-2 was twice than the current obtained for bare PGE. Additionally, the effect of pH of the supporting electrolyte and reaction kinetic were studied. The heterogeneous electron transfer rate constant was calculated to be 0.01 s−1. Moreover, CV study revealed that the redox reaction of catechol was a quasi-reversible and diffusion-controlled process. The square wave voltammetry (SWV) technique was applied for the quantitative determination of catechol. The peak current showed a linear dependency on the concentration of catechol from 3 to 150 µM. Furthermore, the analyte could be detected as low as 3.86 µM. Likewise, the sensor demonstrates a good selectivity towards the target analyte than the other possible interfering molecules or ions. Aiming to examine practical applicability, real samples, such as river and household tap water, were tested by using the proposed transducer, and the satisfactory recoveries demonstrate the effectiveness of Am-PGE-2 in real life applications.

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.

Electrochemical evaluation and determination of vindesine used in cancer chemotherapy at disposable pencil graphite electrode by voltammetric method

Electrochemical evaluation and determination of vindesine used in cancer chemotherapy at disposable pencil graphite electrode by voltammetric method

Electrochemical sensor based on bio-inspired molecularly imprinted polymer for sofosbuvir detection.

The electropolymerized molecularly imprinted polymers (MIP) have enabled the utilization of various functional monomers with superior selective recognition of the target analyte template. Methyldopa is an attractive synthetic dopamine analogue which has phenolic, carboxylic, and aminic functional groups. In this research, methyldopa was exploited to fabricate selective MIPs, for the detection of sofosbuvir (SFB), by a simple electropolymerization step onto a disposable pencil graphite electrode (PGE) substrate. The interaction between methyldopa, as a functional monomer, and a template has been investigated experimentally by UV spectroscopy. A polymethyldopa (PMD) polymer was electrografted onto PGE in the presence of SFB as a template. X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (ESI), and cyclic voltammetry (CV) were used for the characterization of the fabricated sensor. Differential pulse voltammetry (DPV) of a ferrocyanide/ferricyanide redox probe was employed to indirectly detect the SFB binding to the MIP cavities. The sensor shows a reproducible and linear response over a dynamic linear range from 1.0 × 10-11 M to 1.0 × 10-13 M of SFB with a limit of detection of 3.1 × 10-14 M. The sensor showed high selectivity for the target drug over structurally similar and co-administered interfering drugs, and this enabled its application to detect SFB in its pharmaceutical dosage form and in spiked human plasma samples.

Voltammetric Determination of Favipiravir Used as an Antiviral Drug for the Treatment of Covid-19 at Pencil Graphite Electrode.

This work describes the sensitive voltammetric determination of favipiravir (FAV) based on its reduction for the first time with a low-cost and disposable pencil graphite electrode (PGE). In addition, the determination of FAV was also performed based on its oxidation. Differential pulse (DP) voltammograms recorded in 0.5 M H2SO4 for the reduction of FAV show that peak currents increase linearly in the range of 1.0 to 600.0 μM with a limit of detection of 0.35 μM. The acceptable recovery values (98.9-106.0 %) obtained from a pharmaceutical tablet, real human urine, and artificial blood serum samples spiked with FAV confirm the high accuracy of the proposed method.

Fast, Cheap and Reliable Monitoring of Microalgae-Based Paracetamol Removal from Aquatic Environment Using Electrochemical Sensor Technology

Paracetamol (PRL) is an analgesic and antipyretic drug, and its consumption has increased all across the world during the COVID-19 pandemic era. However, its excessive consumption makes it an endocrine-disrupting factor, and it is toxic for the liver. It easily contaminates water resources due to its high solubility, and has substantial potential to access both aquatic life and humans. Therefore, its removal by sustainable methods is a highlighted issue for today’s world that has experienced increasing scarcity of water. Herein, microalgae-based PRL removal and its electrochemical monitoring were performed. The removal performed with Scenedesmus sp. was monitored by disposable pencil graphite electrodes and cyclic voltammetry. The removal was achieved without the requirement of complex procedures, and the monitoring of this removal finished in less than 1 min. Application of the system in real life was tested in the presence of tap water. The biosorption kinetics, isoterms, and changes in chlorophyll content of the microalgae were calculated, and the microscopic characterizations of the biosorption were performed. The selectivity of the system was studied against other water contaminants. This is the first study about the removal of PRL using Scenedesmus sp. and the monitoring of the removal using disposable electrochemical sensor technology.

Electrochemical study and forensic electroanalysis of fungicide benzovindiflupyr using disposable graphite pencil electrode

Nowadays, the use of pesticides in world agriculture is fundamental. However, it leads to an increase in the illegal sale and smuggling of these products in various parts of the world, mainly in Brazil. Therefore, the development of new analytical methods for screening and analysis of these kind of substances is a relevant issue. We present in this work, for the first time, an electrochemical study and a novel electroanalytical method for determination of fungicide benzovindiflupyr (BENZO). According to our knowledge, the electrochemical behavior of BENZO, as well as its voltammetric determination, have never been reported before. The sensors used here consisted of disposable pencil graphite electrodes (PGEs). On this electrode surface and at optimal pH, BENZO behaved according to a quasi-reversible system and showed two voltammetric peaks, one anodic at Ep = +0.59 V and another cathodic at Ep = +0.43 V. The analytical studies utilized BENZO anodic sweep and square-wave adsorptive stripping voltammetry (SWAdSV). All experimental and instrumental parameters were fully investigated and optimized. Under the best conditions, a calibration plot was obtained in the concentration range from 0.10 to 12.5 μmol L−1. The limits of detection (LOD) and quantification (LOQ) achieved were 0.023 and 0.076 μmol L−1, respectively. An electrochemical mechanism for BENZO oxidation was also proposed. The method developed here was successfully employed for the qualitative and quantitative forensic analysis of BENZO in smuggled products, showing good accuracy (recoveries ca. 104%) and precision (relative standard deviation < 5%). These data attest the potential for use of this method in forensic area.

Determination of Paracetamol on Electrochemically Reduced Graphene Oxide-Antimony Nanocomposite Modified Pencil Graphite Electrode Using Adsorptive Stripping Differential Pulse Voltammetry.

A simple, highly sensitive, accurate, and low-cost electrochemical sensor was developed for the determination of over-the-counter painkiller, paracetamol (PC). The enhanced sensing capabilities of the developed sensor were fabricated by the single-step modification of disposable pencil graphite electrodes (PGEs) with the simultaneous electrochemical reduction in graphene oxide and antimony (II) salts. For this purpose, an electrochemically reduced graphene oxide–antimony nanoparticle (ERGO-SbNP) nanocomposite material was prepared by trapping metallic nanoparticles between individual graphene sheets in the modification of PGEs. Structural characterization by FTIR and Raman spectroscopy was employed to confirm the presence of oxygen functional groups and defects in the conjugated carbon-based structure of GO. Morphological differences between the modified PGEs were confirmed by HRTEM and HRSEM for the presence of nanoparticles. The modified electrodes were further electrochemically characterized using CV and EIS. The electrooxidation of PC on an ERGO-SbNPs-PGE was achieved by adsorptive stripping differential pulse voltametric analysis in 0.1 mol·L−1 phosphate buffer solution at pH = 7.0. The optimum current response was used to record a detection limit of 0.057 µmol·L−1 for PC. The electrochemical sensor was further used in real sample analysis for a commercially available pharmaceutical tablet (500 mg PC), for which the percentage recovery was between 99.4% and 100.8%.

Kinetic and thermodynamic studies on the interaction between calf thymus DNA and food additive vanillin - electrochemical methods

• First electroanalytical method for interaction of vanillin with calf thymus-DNA in aqueous medium. • Vanillin can bind to ds-DNA via intercalative and electrostatic binding modes. • Kinetic and thermodynamic parameters were studied for free vanillin and vanillin bounded in DNA complex and discussed. This work describes a voltammetric study on the interaction of double-stranded calf thymus DNA (ds-DNA) and the food additive vanillin. To this end, a disposable pencil graphite electrode (PGE) was used as a voltammetric probe in aqueous media. The free vanillin has an irreversible oxidation signal in acetate buffer solution, pH 4.8. The changes in this signal in the presence of ds-DNA were followed by differential pulse voltammetry (DPV). Using the data obtained by Cyclic Voltammetry (CV), the kinetic parameters, diffusion coefficient (D), heterogeneous rate constant (k s ), and electrode surface concentration ( Γ) of free vanillin was evaluated. The values of these parameters found before and after complex formation between vanillin and DNA were compared to judge the interactions. The binding constant (K) and Gibbs free energy change (ΔG°) of the interaction were found as 1.78 × 10 4 M −1 and −24.25 kJ mol −1 , respectively. The effect of ionic strength on the interaction of vanillin and ds-DNA was also investigated. The results obtained indicate the existence of an interaction between vanillin and ds-DNA. Vanillin binds to DNA both through intercalation and electrostatic attraction. The binding constant related to the vanillin-DNA interaction was comparable to the literature values found by UV–Vis studies.

3D CoMoO4 nanoflake arrays decorated disposable pencil graphite electrode for selective and sensitive enzyme-less electrochemical glucose sensors.

Three-dimensional (3D) cobalt molybdate (CoMoO4) hierarchical nanoflake arrays on pencil graphite electrode (PGE) (CoMoO4/PGE) are actualized via one-pot hydrothermal technique. The morphological features comprehend that the CoMoO4 nanoflake arrays expose the 3D, open, porous, and interconnected network architectures on PGE. The formation and growth mechanisms of CoMoO4 nanostructures on PGE are supported with differentstructural and morphological characterizations. The constructed CoMoO4/PGE is operated as an electrocatalytic probe in enzyme-less electrochemical glucose sensor (ELEGS), confronting the impairments of cost- and time-obsessed conventional electrode polishing and catalyst amendment progressions and obliged the employment of a non-conducting binder. The wide-opened interior and exterior architectures of CoMoO4 nanoflake arrays escalate the glucose utilization efficacy, whilst the intertwined nanoflakes and graphitic carbon layers, respectively, of CoMoO4 and PGE articulate the continual electron mobility and catalytically active channels of CoMoO4/PGE. It jointly escalates the ELEGS concerts of CoMoO4/PGE including high sensitivity (1613 μA mM-1cm-2), wide linear glucose range (0.0003-10mM), and low detection limit (0.12µM) at a working potential of 0.65V (vs. Ag/AgCl) together with the good recovery in human serum. Thus, the fabricated CoMoO4/PGE extends exclusive virtues of modest electrode production, virtuous affinity, swift response, and excellent sensitivity and selectivity, exposing innovative prospects to reconnoitring the economically viable ELEGSs with binder-free, affordable cost, and expansible 3D electrocatalytic probes.

A pencil graphite-based disposable device for electrochemical monitoring of sulfanilamide in honey and water samples.

The present paper reports a simple, fast, and inexpensive process of manufacturing a disposable pencil graphite electrode (PGE) from widely available materials, which showed a reproducibility of at least 7.5%. The electrode was compared to the commercial glassy carbon electrode (GCE) and showed superior electroanalytical performance for sulfanilamide (SFA) with approximately 3.9-fold higher current density. Additionally, a displacement of the oxidation peak from approximately 80 mV to more cathodic regions was observed. Therefore, a method based on square wave voltammetry (SWV) was developed for the determination of the antimicrobial SFA in honey and tap water samples using the proposed sensor. The optimized method presented good detectability (LOD = 2.37 μmol L-1), with excellent precision and accuracy (relative standard deviation < 4.2%) and percent recovery from spiked samples ranging from 92 to 97%. In addition, the sensor did not suffer significant interference from sample matrix components and other commonly evaluated antimicrobials, which demonstrates the potential of these electrodes for implementation in routine analysis and quality control.

Low cost, trouble-free disposable pencil graphite electrode sensor for the simultaneous detection of hydroquinone and catechol

This work proposes, one of the simplest methods for the modification of pencil graphite electrode (PGE) using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques. The electrochemical modification (pre-treatment) of the PGE was carried out in 0.1 M NaOH using CV technique by applying a potential in between −0.4 V and 1.4 V. In the presence of phosphate buffer (scan rate-50 mV s-1, 0.2 M, pH ∼ 7.4), the active surface of the pre-treated pencil graphite electrode exhibits improved sensing properties towards the determination of catechol (CC) and hydroquinone (HQ) with improved sensitivity and reproducibility. Sensing characteristics were evaluated under various experimental conditions (scan rate, analyte concentration, interference study & pH variation) for HQ and CC using pre-treated pencil graphite electrode (PPGE). Scan rate dependent sensing study shows that the electrode process is diffusion-controlled at the modified electrode. The pre-treated pencil graphite electrode showed the lower detection limits for HQ and CC is 0.85 μM & 0.59 μM respectively with a wide linear range (HQ: 0.4 to 1.2 × 10−4 M, CC: 0.1 × 10−4 M to 0.7 × 10−4 M). Experimented pre-treated pencil graphite electrode was used and tested for the water from house hold tap which also showed high sensitivity towards HQ and CC.

Simple Electrochemical Chloramphenicol Assay at a Disposable Pencil Graphite Electrode by Square Wave Voltammetry and Linear Sweep Voltammetry

Chloramphenicol (CAP) is a widely used, broad spectrum antibiotic that contains a nitrobenzene moiety with a possible poisonous feature. Thus, the development of low cost, simple, and rapid analytical methods for the reliable CAP quantification is necessary. Starting from the nitro group electroactivity, the cyclic voltammetric properties of CAP were investigated at the common commercially available, disposable pencil graphite electrode (PGE). The effect of the electrode material, the electrolyte pH and the potential scan rate were investigated. At 2H type PGE, the CAP cyclic voltammograms presented an anodic and two cathodic diffusion controlled, pH-dependent peaks, each involving the exchange of two electrons and two protons. Based on CAP main reduction peak at PGE in pH 5.00 Britton Robinson buffer, a square wave voltammetric (SWV) method was developed for its quantification from 2.50 × 10−6 to 7.50 × 10−4 mol L−1 with a limit of detection (LoD) of 1.39 × 10−6 mol L−1. Moreover, the anodic peak was also employed for the first time for a CAP linear sweep voltammetric (LSV) assay (2.50 × 10−6 to 1.00 × 10−3 mol L−1; LoD 6.09 × 10−7 mol L−1 CAP). Both voltammetric methods using the cost-effective PGE were applied for the determination of CAP in pharmaceuticals, obtaining recoveries of 100.9 ± 1.4% (relative standard deviation of 3.54%) for SWV and 100.7 ± 1.4% (relative standard deviation of 3.55%) for LSV.

Disposal graphite pencil sensor for trace detection of phthalic acid diamide insecticide flubendiamide in wastewater and white rice

ABSTRACT An analytical method for the determination of Flubendiamide (FBD) was investigated for the first time in this study using disposable pencil graphite electrodes (PGE). A detailed study of the electrochemical properties of FBD was carried out in phosphate buffer solution (PBS, pH 7.0). The results showed a well-defined reversible system result from the transformation of FBD to the corresponding hydroxyl-derivative. The results showed a linear range from 1 to 500 µM (R2 = 0. 9952), as well as detection limit of 0.53 µM. The PGE sensor was successfully applied for the detection of FBD in wastewater and white rice.