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Paper‐based thermoelectric generators are a promising and economical alternative to expensive organic conductors that are normally preferred for flexible generators. In the present work, graphite pencil traces on regular Xerox paper are successfully employed to constitute a thermoelectric generator. In conjunction with polyethylenimine polymer, the graphite traces act as both the p‐type and n‐type thermoelectric "legs," of a graphite‐based thermoelectric generator. The fabrication method is facile and requires no conducting paste or silver paste to connect individual thermoelectric legs. A test module containing five pairs of p‐n legs is fabricated on paper to test its performance. The device produces a thermoelectric voltage of 9.2 mV, generating an output power of 1.75 nW at a temperature difference of ≈60 K. The present work demonstrates that ordinary pencil on paper may be used as the foundation for a cheap, flexible, easily disposable, and environmentally friendly thermoelectric generator. [ABSTRACT FROM AUTHOR]

Electronic capacitors were constructed via hand-printing on paper using pencil graphite. Graphite traces were used to draw conductive connections and capacitor plates on opposing sides of a sheet of standard notebook paper. The paper served as the dielectric separating the plates. Capacitance of the devices was generally < 1000 pF and scaled with surface area of the plate electrodes. By combining a pencil-drawn capacitor with an additional resistive pencil trace, an RC low-pass filter was demonstrated. Further utility of the pencil-on-paper devices was demonstrated through description of a capacitive force transducer and reversible chemical sensing. The latter was achieved for water vapor when the hygroscopic cellulose matrix of the paper capacitor’s dielectric adsorbed water. The construction and demonstration of pencil-on-paper capacitive elements broadens the scope of paper-based electronic circuits while allowing new opportunities in the rapidly expanding field of paper-based sensors. [ABSTRACT FROM AUTHOR]

Pencil traces drawn on print papers are shown to function as strain gauges and chemiresistors. Regular graphite/clay pencils can leave traces composed of percolated networks of fine graphite powders, which exhibit reversible resistance changes upon compressive or tensile deflections. Flexible toy pencils can leave traces that are essentially thin films of graphite/polymer composites, which show reversible changes in resistance upon exposure to volatile organic compounds due to absorption/desorption induced swelling/ recovery of the polymer binders. Pencil-on-paper devices are low-cost, extremely simple and rapid to fabricate. They are light, flexible, portable, disposable, and do not generate potentially negative environmental impact during processing and device fabrication. One can envision many other types of pencil drawn paper electronic devices that can take on a great variety of form factors. Hand drawn devices could be useful in resource-limited or emergency situations. They could also lead to new applications integrating art and electronics. [ABSTRACT FROM AUTHOR]

• Pyrolyzed pencil graphite coated cellulose paper used as an interlayer. • Studied effect of different grades of pencil over cellulose paper on Li-S cell. • Pencil is a source of graphite and silica in the interlayer and act as a reservoir to lithium polysulfides. • The DFT calculations performed to calculate interaction between polysulfides and graphite/silica structures. • Capacity values of 1352 and 995 mAh g−1 are attained at 0.1 and 0.5 A g−1. • Cycling stability of 900 mAh g−1 at 1 A g−1 (3.0C) for 350cycles. Lithium-sulfur (Li-S) battery is next generation battery technology but it's commercialization is obstructed primarily due to the shuttling effect of lithium polysulfides (LiPSs). Herein, we report an effective approach using pencil coated pyrolyzed cellulose filter paper as an interlayer to suppress the LiPSs dissolution into the electrolyte and thus allowing effective utilization of active sulfur cathode. Here, the binder clay particles (mainly SiO 2) of pencil graphite facilitate the adsorption of LiPSs, whereas graphite increases the electrical conductivity and acts as a physical barrier to LiPSs. To investigate further, we utilize three different grades of pencil (4B, HB, 5H) which vary in terms of clay (SiO 2) composition. It is observed that the HB pencil coated interlayer has the right balance of silica and graphite, which results in an impressive initial capacity of 1352 and 995 mAh g−1 at the current density of 0.1 and 0.5 A g−1, respectively. The cell exhibit high cycling stability of 900 mAh g−1 at 1 A g−1 (3.0 C) for 350 cycles with a slow capacity decay of 0.07% per cycle. The phenomenon of LiPSs adsorption is further understood using post-cycling analysis, H-cell adsorption testing, and shuttle factor calculation for the development of commercial Li-S batteries. [ABSTRACT FROM AUTHOR]

Tunable piezoresistive sensors based on a drawing on paper with different grades of pencils are proposed. While an external mechanical strain is applied to U-shape resistors prepared by pencil drawings on paper, an increase in the gauge factor with an increase in the graphite resistance is found. The result is attributed to the tunneling effect between neighboring graphite during the drawing process, further suggesting that different-grade pencil drawings can tune the piezoresistive properties. Through many cycles of repeatedly applied and released force, the output voltage for an HB pencil was found to be more sensitive than that for a 9B pencil. [ABSTRACT FROM AUTHOR]

This study investigates potentiodynamic synthesis of polyaniline (PANI) using pencil graphite electrodes (PGEs), aiming to elucidate deposition mechanisms under simple experimental conditions. By exploring PANI electrosynthesis through electrochemical, spectroscopic, and computational approaches, valuable insights into the physicochemical aspects of aniline polymerization are gained. The proposed synthetic method was challenged for the development of a new molecularly imprinted polymer for chloramphenicol on the surface of PGEs to obtain an innovative impedimetric sensor. The sensing platform shows a linear response in the target concentration range between 0.1 and 17.5 nM, in aqueous solutions, with a limit of detection of 0.03 nM and a limit of quantification of 0.09 nM. The results obtained suggest that the synthesis method proposed provide a way to obtain stable and electroactive polyaniline film with huge potential application. [ABSTRACT FROM AUTHOR]

Herein the synergistic properties of electrochemically reduced graphene oxide–antimony nanoparticles (ERGO-SbNPs) were leveraged for the ultrasensitive determination of bisphenol A (BPA) in water samples using disposable pencil graphite rods. A novel pencil-graphite multi-electrode array was utilized as the coating tool resulting in the production of highly reproducible and disposable single-use ERGO-SbNP-coated pencil graphite rods. This coating method effectively mitigated the fouling caused by BPA by-products during oxidation. The analytical determination of BPA oxidation on the single-use ERGO-SbNP-coated pencil graphite rods demonstrated an impressive 0.0,125 µM detection limit, surpassing the USEPA drinking water standard of 0.087 µM. Furthermore, the developed electrochemical sensor exhibited exceptional reproducibility for BPA in tap water samples from Western Cape, South Africa with few interferences. The study's findings not only highlight the sensor's superior performance but also present a promising alternative to existing anti-fouling measures. [ABSTRACT FROM AUTHOR]

Multifunctional and low-cost electrode materials are desirable for the next-generation sensors and energy storage applications. This paper reports the use of pencil graphite as an electrode for dual applications that include the detection of free residual chlorine using electro-oxidation process and as an electrochemical energy storage cathode. The pencil graphite is transferred to cellulose paper by drawing ten times and applied for the detection of free residual chlorine, which shows a sensitivity of 27 μA mM-1 cm-2 with a limit of detection of 88.9 μM and linearity up to 7 mM. The sample matrix effect study for the commonly interfering ions such as NO3-, SO42-, CO32-, Cl-, HCO3- shows minimal impact on free residual chlorine detection. Pencil graphite then used after cyclic voltammogram treatment as a cathode in the aqueous Zn/Al-ion battery, showing an average discharge potential plateau of ~1.1 V, with a specific cathode capacity of ~54.1 mAh g-1 at a current of 55 mA g-1. It maintains ~95.8% of its initial efficiency after 100 cycles. Results obtained from the density functional theory calculation is consistent with the electro-oxidation process involved in the detection of free residual chlorine, as well as intercalation and de-intercalation behavior of Al3+ into the graphite layers of Zn/Al-ion battery. Therefore, pencil graphite due to its excellent electro-oxidation and conducting properties, can be successfully implemented as low cost, disposable and green material for both sensor and energy-storage applications. [ABSTRACT FROM AUTHOR]

This paper presents a simple, sensitive, selective, cost-effective indirect voltammetric method for determining hydrazine using a poly(Eriochrome black T) modified pencil graphite electrode (p-EBT-PGE). Alizarin Red S (ARS) was used as a mediator in acetic acid–acetate buffer (pH 5.5) and 0.2 M KCl. The difference between the mediator's oxidation currents measured in hydrazine's presence and absence served as the analytical response for voltammetrically determining hydrazine. The ARS–hydrazine system's voltammetric properties at the p-EBT-PGE were also investigated. The limit of detection and two analytical ranges of the method were estimated to be 0.87 nM and 2.9 to 10.0 nM and 3.0 to 60.0 μM. The method has the best limit of detection among reported voltammetric methods. The recoveries in tap water, wastewater, and drinking water samples were between 99.60% and 104.74%, while the relative standard deviations were between 1.6 and 4.2. Uncertainty calculations were also evaluated for hydrazine-spiked samples by following a top–down approach. [ABSTRACT FROM AUTHOR]

This paper describes a novel approach to detect Cd(II) using the combination of the differential pulse anodic stripping voltammetry and magnetic nanoparticle based dispersive solid phase microextraction as an efficient, green and accurate method. Currents of Cd(II) increased linearly in the range from 75 to 2000 ng L−1 Cd(II) with a detection limit of 21.6 ng L−1. The RSD values of 2.6 and 6.0 % for 1.00 and 0.10 μg L−1 respectively showed that proposed method has an acceptable repeatability. Recovery values between 92.3 and 98.6 % showed that this approach can be successfully used for determination of Cd(II) in water samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Graph: On the cover. "The View from My Window, 2004" (oil pastels, color pencils and graphite on paper) by Matteo Pericoli (). [Extracted from the article]

The article offers ideas on creating capacitors by drawing graphite lines on paper or plastic. Graphite lines can function as resistors for resistivity experiments. They can be used to analyze the dependence of capacitance on plate area and separation. Using a pencil with very soft lead is recommended in constructing graphite lines. When using plastic, surfaces should be slightly roughened to that graphite can attach to it.

In this study, a sensitive electrochemical method was developed for the determination of hydroxylamine (H−A) using a curcumin‐modified pencil graphite electrode prepared with the electropolymerization of curcumin (PolyCurc‐PGE). The PolyCurc‐PGE showed a remarkable electrocatalytic response for H−A oxidation compared with bare PGE. Amperometric and cyclic voltammetric measurements were performed based on the electrocatalytic oxidation of H−A at PolyCurc‐PGE. Some parameters, such as monomer concentration, pH, and cycle number during electropolymerization, were optimized to obtain the best electrochemical response of the modified electrode towards H−A. Results show that the PolyCurc‐PGE gives a linear response towards H−A oxidation in the range from 0.50 μM to 500 μM (R2=0.9984). In addition, the sensitivity and detection limit (LOD) of PolyCurc‐PGE were found to be 5432 μA mM−1 cm2 and 0.15 μM H−A, respectively. The developed amperometric method was successfully applied to determine H−A in pharmaceutical and water samples, and acceptable results were obtained with high accuracy and precision. [ABSTRACT FROM AUTHOR]

The present paper describes the voltammetric analysis of dipyridamole (DIP) at a cheap, disposable pencil graphite electrode (PGE). The working conditions were optimized with regard to the electrode material and the supporting electrolyte. Cyclic voltammetric investigations emphasized that DIP is irreversibly oxidized at the PGE. The electrode process is pH-dependent and controlled by both diffusion and adsorption. For DIP quantitative determination a differential pulse voltammetric (DPV) method in phosphate buffer solution pH 7.00 was developed. DIP's oxidation peak current varied linearly with the analyte concentration, presenting two linear ranges, namely 5.00 x 10-7 -2.50 × 10-5 M and 2.50 × 10-5 -2.50 × 10-4 M, with detection and quantification limits of 1.21 × 10-7 M and 4.03 × 10-7 M DIP, respectively. The newly developed DPV method using the inexpensive, disposable PGE was successfully applied for the simple and rapid determination of DIP from pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

For the first time, silver nanoparticles (AgNPs) were fabricated with graphite pencil electrode (GPE) by immersing a bare hard black pencil (HB pencil) in AgNO3 solution mixed with extract Quercus infectoria solution, followed by placing directly against to UV lamp (254 nm) and kept for 30 min. Silver modified-GPEs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometer (EDX). The silver nanoparticles fabricated with graphite pencil electrode (AgNPs-GPE) showed excellent selectivity to chloride ion, as well as excellent reproducibility, together with it has several advantages such as sensitivity, simplicity, low cost, green, and fast response. The maximum oxidation cyclic voltammogram current of the AgNPs-PGE was found at 160 mV. The linear range of chloride ions detection is between (0.8-52 mmol L-1), and the limit of detection (LOD) of chloride ions is 0.041 mmol L-1. Finally, the Silver fabrication electrode was used to determine the chloride ion concentration in drugs, such as phenylephrine, metformin, procaine, and dopamine formulated with hydrochloride, and satisfactory results were obtained. [ABSTRACT FROM AUTHOR]

Pencil graphite electrode (PGE) modified with MWCNT and Bi3+ (MWCNT/Bi/PGE) was utilized in simultaneous analysis of Pb2+, Cd2+, and Zn2+. Surface and electrochemical characteristics of MWCNT/Bi/PGE were investigated via SEM, cyclic voltammetry, electrochemical impedance spectroscopy, and FTIR measurements. Even though modification with MWCNT did not improve the electroactive surface area, it significantly decreased the charge transfer resistance. Furthermore, modification with Bi3+ significantly increased the sensitivity. Finally, MWCNT/Bi/PGE exhibited the highest sensitivity and reproducibility compared to PGE and PGE modified with only MWCNT. MWCNT/Bi/PGE provided LOD values of 0.27, 0.43, and 1.63 μg L−1, and linear ranges of 1–80, 5–80, and 10–80 μg L−1 for Pb2+, Cd2+, and Zn2+, respectively. Proposed modification method offers effective electroanalytical performance with low time consumption and cost for the analyst. [ABSTRACT FROM AUTHOR]

A sensitive and inexpensive differential pulse voltammetric technique was applied to investigate the electrochemical behavior of alfuzosin hydrochloride at two different working electrodes: silica gel modified carbon paste and pencil graphite electrodes (PGE). The voltammetric conditions were optimized using cyclic voltammetry, showing an irreversible anodic peak in Britton-Robinson buffered medium (pH 6) at 0.86-0.90 V. The electrochemical responses were linearly correlated with alfuzosin concentrations (R2 > 0.999) in the ranges of 0.6-20 and 0.3-20 µM, exhibiting higher electrocatalytic activity at PGE with a low detection limit/detectability of 0.099 µM. In addition, this study was a successful attempt for the drug determination in tablets and spiked urine samples with green profile evaluation, employing the National Environmental Methods Index, analytical Eco-Scale score, and Green Analytical Procedure Index. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Graphite as the most common polymorph of naturally occurring crystalline carbon is required for many different applications such as batteries, refractories, electrical products, and pencils. Graphite resources are currently being subjected to intensive exploration to help meet rapidly growing global demand – and graphite has made it onto the list of critical raw materials as issued by the European Union. Graphite ore is mostly beneficiated using flotation separation techniques. The increasing demand for high-grade graphite products with up to 99.99% carbon has resulted in the development of various approaches to remove impurities even to parts per million range. This paper considers separation and purification techniques that are currently employed for graphite mineral beneficiation, and identifies areas in need of further research. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Pencil graphite electrode was employed for the first time for determination of Etofenamate. • Benefits of method: rapidity, simplicity, sensitivity and repeatability. • The procedure was successfully applied to determination of Etofenamate urine and drug samples. [ABSTRACT FROM AUTHOR]

• Evanescent fiber optic sensing and DFT approach in graphite pencil powder introduced. • Black graphite pencil powder exhibited better sensitivity for ethanol at room temperature. • DFT analysis supported the experimental results with better adsorption energy and distance. This study investigated the ethanol-sensing properties of pencil graphite using a fiber optic gas sensor. The results were further confirmed using density functional theory (DFT). The sensor showed good sensitivity (18 counts/100 ppm) and response time (70 sec). The electronic analysis of pure and ethanol-adsorbed graphite powders was also conducted using their band structures, Density of States (DOS), and projected Density of States (PDOS). For ethanol-adsorbed graphite, it was shown that there were significant alterations in band structure and density of states, providing insights for gas sensing applications. [ABSTRACT FROM AUTHOR]

A sensitive differential pulse (DP) voltammetric method has been proposed for the determination of trifluralin (TFA) based on both its reduction and oxidation at a disposable pencil graphite electrode (PGE). DP voltammograms recorded under optimized conditions show that oxidation and reduction peak currents increased linearly in the range from 1.0 to 75.0 μM and from 0.50 to 100.0 μM TFA, respectively. LOD and sensitivity values have been determined as 0.39 μM and 11170 μA mM−1 cm−2 for oxidation and as 0.20 μM and 22167 μA mM−1 cm−2 for reduction. The acceptable recovery values (95.2–104.8 %) were obtained from real water samples. [ABSTRACT FROM AUTHOR]

In this study, we present a strategy for the specific electrochemical detection of NADH in human blood serums using modified electrode fabricated by intercalation of tetrabutylammonium ions (TBA+) into pencil graphite electrode (TBA+/PGE). In order to implement this protocol, a modification process in the potential range (−0.2) to (−2.75) V was performed in DMSO containing 0.1 M TBAP by CV method. The characterization processes of the prepared sensor were carried out using CV, EIS, FT‐IR, XPS, and SEM methods. The electrode fabricated by intercalation of TBA+ was found to be able to analyze NADH at +0.32 V applied potential by the amperometric method. The LOD was detected as 0.46 μM. The analysis results of human blood serums which are taken from healthy individuals show that TBA+/PGE can be used for real samples. The results indicated that TBA+/PGE can be easily fabricated by one‐step and one‐pot electrochemical method and TBA+/PGE can be used as a potential sensor for the NADH determination. [ABSTRACT FROM AUTHOR]

• Conductive colloidal solution of graphene synthesized via electrochemical exfoliation of 9B pencil graphite core was used for sensing LPG at ppm levels in air. • A self-assembled network of exfoliated graphene successfully fabricated on flexible polymer substrate exhibited appreciably high sensitivity to inflammable LPG. • The principal of operation of the present resistive LPG sensor rely on the variation in the electrical resistance of the self-embedded exfoliated graphene network on its exposure to the gaseous analyte i.e LPG in a two-pole format. • On the basis of this fact qualitative as well as quantitative detection of the LPG with sensor response of 24.5 % and response time of 18 s at sensing limit as low as 50 parts-per-million (ppm) is achieved. • Experimental investigations unveiled a competent LPG sensor which can sense and compute LPG leakage with prolonged high constancy and reproducibility. The present paper illustrates a description on material synthesis, sensor fabrication and electronic prototyping of a cost effective, reusable, stable and highly sensitive and selective device for the sensing and quantification of trace concentrations of liquefied petroleum gas (LPG) in ambient conditions. Conductive colloidal solution of graphene synthesized via electrochemical exfoliation of 9B pencil graphite core was used for sensing LPG at ppm levels in air. In comparison to other metal oxide semiconducting (MOS) materials, electrochemically exfoliated graphene is very well recognized owing to its very economic prices and abundant availability of its raw material i.e. graphite, ease of fabrication and simple modification techniques. A self-assembled network of exfoliated graphene successfully fabricated on flexible polymer substrate exhibited appreciably high sensitivity to inflammable LPG. The principal of operation of the present resistive LPG sensor relies on the variation in the electrical resistance of the self-embedded exfoliated graphene network on its exposure to the gaseous analyte i.e. LPG in a two-pole format. The degree of variation in electrical resistance of the sensitive film depends on the concentration of the LPG to which it is exposed. On the basis of this fact qualitative as well as quantitative detection of the LPG with sensor response of 24.5 % and response time of 18 s at sensing limit as low as 50 parts-per-million (ppm) is achieved. Experimental investigations unveiled a competent LPG sensor which can sense and compute LPG leakage with prolonged high constancy and reproducibility. [ABSTRACT FROM AUTHOR]

Commercially available high quality 9B pencil graphite was used for sensing of trace concentrations of nitrogen dioxide (NO2) and ammonia (NH3) at sub-ppm levels in air at ambient temperature and pressure. The pencil graphite was characterized using scanning electron microscopy (SEM), Raman spectroscopy and powder X-ray diffraction (XRD) techniques. In comparison to other sensing materials pencil graphite is very well recognized owing to its cheaper price, simplicity of fabrication, abundant over-the-counter obtainability and easy modification. The principal of operation of the chemiresistive gas sensor is based on the variation in the electrical resistance due to the selective interaction between the pencil graphite network and the specific gaseous analyte in a two-pole format. The degree of change in electrical resistance of the pencil graphite network depends on the concentration of the gaseous analyte to which it is exposed. On the basis of this fact qualitative as well as quantitative detection of the gaseous analytes can be achieved. The sensing limits of 100 parts-per-billion (ppb) and 500 ppb with sensor response times of ∼30 s and ∼50 s for NO2 and NH3, respectively is recorded using our gas detector, and are found significantly efficient in comparison to the NO2 and NH3 detectors available commercially in market. [ABSTRACT FROM AUTHOR]

[Display omitted] • A practical electrochemical method for the determination of NDM-1 inhibitors' activity in vitro has been established. • The results of the DPV-PGE method and UV-Vis method are consistent for typical NDM-1 inhibitors (EDTA and L -captopril). • A complementary method for NDM-1 inhibitor screening in vitro avoiding interference from UV-Vis absorption of inhibitors. A practical electrochemical method for the determination of the inhibitory activity of New Delhi metallo-β-lactamase-1 (NDM-1) inhibitors was established with a bare pencil graphite electrode (PGE) as the working electrode and imipenem as the substrate. To validate the method, the well-known NDM-1 inhibitors EDTA and L -captopril were selected for the corresponding assays with IC 50 values of 1.22 ± 0.20 μM and 22.92 ± 1.19 μM, respectively. These results were consistent with those (5.48 ± 0.32 μM for EDTA and 69.13 ± 6.01 μM for L- captopril) from the UV–vis high-throughput assay method. Further investigation regarding the steady kinetics of a typical competitive inhibitor of L -captopril showed that the two methods provided K i values at the same level, i.e., they are 41.5 ± 3.8 μM (DPV-PGE) and 52.5 ± 2.5 μM (UV–vis), respectively. [ABSTRACT FROM AUTHOR]

A sensitive, simple, fast electrochemical biosensor for the DNA interaction of bevacizumab (BEVA), which is used as a targeted drug in cancer treatment, was developed using the differential pulse voltammetry (DPV) technique with pencil graphite electrode (PGE). In the work, PGE was electrochemically activated in a supporting electrolyte medium of +1.4 V/60 s (PBS pH 3.0). Surface characterization of PGE was carried out by SEM, EDX, EIS, and CV techniques. Determination and electrochemical properties of BEVA were examined with CV and DPV techniques. BEVA gave a distinct analytical signal on the PGE surface at a potential of +0.90 V (vs. Ag/AgCl). In the procedure proposed in this study, BEVA gave a linear response on PGE in PBS (pH 3.0 containing 0.02 M NaCl) (0.1 mg mL−1 – 0.7 mg mL−1) with LOD and LOQ values of 0.026 mg mL−1 and 0.086 μg mL−1, respectively. BEVA was reacted with 20 μg mL−1 DNA in PBS for 150 s and analytical peak signals for adenine and guanine bases were evaluated. The interaction between BEVA-DNA was supported by UV–Vis. Absorption spectrometry and the binding constant was determined as 7.3 × 104. [Display omitted] • Investigation of bevacizumab-DNA interaction by voltammetric and spectroscopic techniques. • Pencil graphide electrode was employed for the first time for determination of bevacizumab. • Benefits of method: rapidity, simplicity and repeatability. [ABSTRACT FROM AUTHOR]

Synthesis of CeO 2 @SiO 2 nanospheres, modification on pencil graphite electrode, electrochemical study of modified electrode as sensor and antimicrobial study of nanospheres have been explored. [Display omitted] • Synthesis of CeO 2 @SiO 2 nanospheres by simple and facile solvothermal and sol–gel method. • Amperometric sensing of ascorbic acid using modified Pencil Graphite electrode (PGE) • Exhibited high sensitivity, 167.5 μA/mM.cm2, low detection limit (70.18 µM) and good linear range. • Additionally, the sensor exhibited high stability with good anti-interference tendency against some interfering species. • The modified sensor also showed high recovery % in real sample analysis. • The nanospheres also performed efficiently against some deleterious bacteria culture. Ascorbic acid (AA), being core vitamin, prompts collagen protein growth that maintains our skin, bones, joint lining's, teeth, gums, blood vessels and even ligament. Initially, synthesis of CeO 2 and SiO 2 nanoparticles and their nano-spheric composite (CeO 2 @SiO 2 NSs) materials through solvothermal and sol–gel routes was achieved. These nanospheres were defensibly characterized through appropriate characterization techniques. Pencil graphite electrode or PGE was modified by drop coating and electrochemically investigated for analytical and real samples with AA detection in phosphate buffer saline. CeO 2 @SiO 2 NSs/PGE electrode showed high sensitivity (167.5 μA/mM.cm2) and low LOD (70.18 µM) for AA. The modified electrode revealed good linear range, high stability, specificity and performed well for real samples' AA detection. CeO 2 @SiO 2 NSs also effectively inhibited multiple bacteria with and without solar irradiation. Overall, the NSs, due to their unique physical, chemical and optical properties offered path towards advance sensing and antibacterial material as well. [ABSTRACT FROM AUTHOR]

POxNPs/PGE = Pyruvate oxidase nanoparticles; PGE = Pencil graphite electrode • Prepared and characterized pyruvate oxidase nanoparticles (POxNPs). • Immobilized POxNPs onto pencil graphite electrode to construct improved amperometric pyruvate biosensor. • Biosensor displayed limit of detection as 0.58 μM within a linear working range, 0.001–6000 μM. • Biosensor measured elevated level of pyruvate in sera of heart patients. • Working electrode showed storage stability of 210 days, while being stored dry at 4 °C. This present study was aimed to fabricate a sensitive and improved amperometric biosensor by the nanoparticles of pyruvate oxidase, which were prepared and immobilized covalently onto pencil graphite electrode. The biosensor showed ideal working within 5 s under defined conditions of pH 6.0 and incubation temperature of 30 °C at an applied voltage of -0.1 V. Under standard assay conditions, a linear response was obtained between pyruvate concentration ranging from 0.001 to 6000 μM and current (μA). A lower detection limit (0.58 μM) and an excellent correlation coefficient (R2 = 0.999) with standard spectrophotometric assay was obtained for the present biosensor. Within and between batches of coefficients of variation were calculated and found to be 3.61 % and 3.33 %, respectively. The biosensor was put to continual use for over 210 days. The biosensor was employed for the measurement of pyruvate level in sera of normal healthy individuals and persons suffering from heart disease. [ABSTRACT FROM AUTHOR]

A disposable nonenzymatic glucose sensor was obtained by pulsed electrodeposition of Pt-CuO on a graphite pencil electrode (GPE). The morphology of the modified GPE was studied using SEM, and the chemical composition of the coating was examined by EDAX and XRD. The electrochemical response of the modified GPE was compared with individual copper- and platinum-modified GPEs. The electrodeposition parameters were optimized with respect to the electrocatalytic activity of the deposits towards glucose oxidation. Best operated at a working potential of 0.6 V vs. Ag/AgCl, the sensor has a sensitivity of 2035 μA mM−1 cm−2, a 0.1 μM detection limit and a wide linear response range that extends up to 25 mM. It is highly selective for glucose in the presence of various exogenous and endogenous interfering species. Eventhough the requirement of alkaline medium for sensing is a limitation, easy fabrication procedure, very high sensitivity and selectivity, wide analytical range, and disposable sensor characteristics show potential application towards blood glucose determination. [ABSTRACT FROM AUTHOR]

A gold (Au) nanoparticle-modified graphite pencil electrode was prepared by an electrodeposition procedure for the sensitive and rapid flow injection amperometric determination of hydrazine (N2H4). The electrodeposited Au nanoparticles on the pretreated graphite pencil electrode surface were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, and electrochemical impedance spectroscopy. Cyclic voltammograms showed that the Au nanoparticle-modified pretreated graphite pencil electrode exhibits excellent electrocatalytic activity toward oxidation of hydrazine because the highly irreversibly and broadly observed oxidation peak at +600 mV at the pretreated graphite pencil electrode shifted to −167 mV at the Au nanoparticle pretreated graphite pencil electrode; in addition, a significant enhancement in the oxidation peak current was obtained. Thus, the flow-injection (FI) amperometric hydrazine sensor was constructed based on its electrocatalytic oxidation at the Au nanoparticle-modified pretreated graphite pencil electrode. The Au nanoparticle-modified pretreated graphite pencil electrode exhibits a linear calibration curve between the flow injection amperometric current and hydrazine concentration within the concentration range from 0.01 to 100 µM with a detection limit of 0.002 µM. The flow injection amperometric sensor has been successfully used for the determination of N2H4 in water samples with good accuracy and precision. [ABSTRACT FROM AUTHOR]

Graphite pencil lead (GPL) covered with Au nanodendrites (AuNDs) (the AuND@GPL sensor) has been demonstrated as an electrochemical sensor for simultaneous detection of Pb(II), Cu(II) and Hg(II) in water samples. To meet both the demands of cost-effectiveness and required analytical performance, a cheap GPL was chosen as a sensor platform and AuNDs providing a large electroactive surface area were fabricated on the surface of GPL by a simple electrodeposition in less than one minute. Due to the incorporation of AuNDs, the sensitivities of simultaneous detection of Pb(II), Cu(II) and Hg(II) were improved with a limit of detection below 0.2 ppb, and the peak intensities did not vary significantly even though concentrations of interferants were 100-fold greater. The sensor-to-sensor reproducibility was good (relative standard deviation below 4.6%), which is mainly contributed to the simple one-step electrodeposition for sensor preparation. The overall detection performance was better or similar in comparison with those of previously reported GPL-based sensors. Moreover, when real lake water samples were analyzed, the AuND@GPL sensor was able to accurately determine the Pb(II), Cu(II) and Hg(II) concentrations. The sensor is cost-effective due to the use of GPL as a platform, so it has a strong potential as a disposable electrochemical sensor for at-site water quality monitoring. [ABSTRACT FROM AUTHOR]

In this study, ZnO nanoflowers (ZnONFs) were synthesized using sonochemical method, which is a simple, environmentally friendly, low-cost and rapid method. ZnONFs was characterized by using FE-SEM, EDS, elemental mapping, FTIR and XRD techniques. Single use pencil graphite electrode (PGE) modified with ZnONFs was characterized using FE-SEM, EDS, elemental mapping, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. This developed electrode was used for the first time for the determination of calf thymus double-stranded DNA (dsDNA) and the chemotherapeutic drug Gemcitabine (GEM) using differential pulse voltammetry (DPV). The detection limits (DLs) of dsDNA and GEM were calculated as 1.91 μg/mL and 2.47 μg/mL, respectively. The interaction of GEM and dsDNA at different times was investigated by measuring the changes in both GEM and guanine oxidation signals by DPV technique. The developed nanoflower-based biosensor responded in as short as 5 min in the DNA-anticancer drug interaction study. The study provides advantages such as low cost, biocompatibility, and easy synthesis of the used nanomaterial synthesis, as well as low detection limit and short interaction time at the sensor stage. [Display omitted] • ZnO nanoflowers modified pencil graphite electrodes (ZnONFs-PGE) were developed. • The electrochemical measurements were performed by DPV, CV and EIS techniques. • The electrochemical monitoring of anticancer drug Gemcitabine and dsDNA interaction was performed. [ABSTRACT FROM AUTHOR]

A novel and label-free electrochemical sensing strategy was explored for designing the ultra-low-level dopamine sensor based on a low-cost pencil graphite electrode (PGE). Electrochemical measurements of the PG electrode towards dopamine detection were performed using the anodic sweeping voltammetry (ASV) technique with optimized deposition voltage and time. With a sensitivity of 0.022 μA nM−1 cm−2, the PG electrode demonstrated sufficient potential for highly selective detection of dopamine down to 26.5 nM concentration in the presence of other interfering bioanalytes. [Display omitted] • Pencil graphite electrode (PGE) shows excellent low-level detection ability of Dopamine. • PGE offers very low-cost sensing strategy for Dopamine sensor. • Bare PGE can detect dopamine down to 26.5 nM. • PGE shows excellent specific selectivity of the Dopamine in the presence of ascorbic and uric acids. • PGE based Dopamine sensor shows 74 % reusibility. [ABSTRACT FROM AUTHOR]

First thing that springs to mind whenever we think of drawing and sketching is a wooden stick called a graphite pencil. It was in 1795 that the Graphite Pencil made its debut. Graphite pencils have been around since the 18th century and are currently going strong in the 21st century. We all know that even in the 21st century, we cannot ignore the pencil's presence and significance. We were taught how to write and draw by the pencil from the very first day of school. Artists have long sought for new art forms, materials, techniques, and instruments. Because everything is moving so quickly in the digital age, artists are also looking for rapid and time-efficient results in their artwork. Thanks to improved technology, artists now have a better digital drawing tool. Using a digital drawing tool is quite comparable to using a traditional drawing pencil in the traditional sense. In this post, we'll take a look at several cutting-edge digital drawing tools and explain how they might benefit artists. [ABSTRACT FROM AUTHOR]

Simultaneous anodic adsorptive stripping voltammetry was applied for selective and sensitive electrochemical determination of the flavones luteolin (LU) and the basic flavone core 3‐hydroxyflavone (3HF) using a renewable pencil graphite electrode (PGE). The increased separation of the anodic peak potential of LU and 3HF on a PGE surface together with the increased sensitivity renders their simultaneous determination feasible by square wave anodic adsorptive stripping voltammetry (SWAASV). The electrochemical parameters such as surface concentration (Γ), electron transfer coefficient (α), and the standard rate constant (ks) of both LU and 3HF at a PGE were calculated. For simultaneous detection of both compounds by synchronous change of the concentration of LU and 3HF, the detection limits were 1.34 nM and 5.15 nM, respectively. The proposed procedure was successfully applied for the simultaneous detection of LU and 3HF in human serum and urine samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A novel and rapid voltammetric assay for the simultaneous determination of monolinuron (MLN) and linuron (LIN) using an electrochemically pretreated pencil graphite electrode (PGE*) is reported for the first time. Enhanced oxidation peak currents of MLN and LIN were observed at PGE* when compared with electrochemically non-pretreated PGE. Differential pulse voltammetric (DPV) results showed distinct anodic peaks at 1.064 V and 1.170 V for MLN and LIN, respectively. Under optimum conditions, the detection limits were 3.7 × 10−7 mol L−1 and 5.8 × 10−7 mol L−1 for MLN and LIN respectively. The DPV method was applied for the quantitative determination of the mentioned compounds in spiked tap water samples enriched by solid phase extraction. The voltammetric results were in good agreement with high-performance liquid chromatography data. • Electrochemically activated pencil graphite electrode (PGE*) • Simultaneous electroanalytical determination of LIN and MLN at PGE* without previous separation • The detection limits were 5.8·10−7 M for LIN and 3.7·10−7 M for MLN. • Voltammetric determination of LIN and MLN in spiked tap water matrices enriched by solid phase extraction using PGE* [ABSTRACT FROM AUTHOR]

Ready-to-use sensing probes have been used to develop a rapid-production, low-cost, fast and sensitive electronic tongue, which consists of electric double-layer microfluidic capacitors. Pencil graphite cores consisting of rough flake-graphite with various ratios of graphite, clay and wax assured differential interactions towards pattern recognition applications. [ABSTRACT FROM AUTHOR]

The presented study focuses on the optimum conditions for chemical activation of pencil graphite electrodes (PGE) used in the determination of bisphenol A (BPA). The prepared ethanol–HCl mixture for chemical activation of pencil graphite electrode exhibits better activation factor compared with traditional activation methods like anodizing. The obtained porous and highly conductive surface of PGE can be used as a sensing device. The electrochemical behavior of BPA at the modified sensor was investigated. The effects of pH, accumulation time and sensor activation were examined. In the optimum experimental conditions, adsorptive differential pulse voltammetry was used for determination of BPA, which exhibits a linear calibration graph of Ip versus BPA concentration in the range 1.25 × 10–8 to 1.34 × 10–4 M. The calculated detection limit for S/N = 3 was 1.0 nM. The presented sensor is reusable. The activated PGE was applied for the determination of BPA leached from baby bottles as a real sample using spike method. [ABSTRACT FROM AUTHOR]

In this study, a sensitive voltammetric method for the determination of vanillin in commercial food products was proposed using a pencil lead as an electrode material. In the cyclic voltammograms of vanillin recorded in pH 8.0 Britton Robinson buffer at the pre-oxidized pencil graphite electrode (p-PGE), a sharp peak was observed at about 520 mV (vs. Ag / AgCl electrode) attributed to the oxidation of vanillin. Subsequently, the voltammetric determination of vanillin based on its oxidation at p-PGE was carried out using the differential pulse voltammetry (DPV) technique under optimized conditions. DPV results showed that the oxidation peak current of vanillin increased linearly in the concentration range of 0.5 to 10.0 µM vanillin with a detection limit of 0.16 µM (based on 3Sb). In the final step, this voltammetric method was applied to the determination of vanillin in vanilla syrup samples. Results were in good agreement with the values indicated on the labels of samples. [ABSTRACT FROM AUTHOR]

Focuses on a study which focused on the field ion and field emission microscopic investigation of pencil lead tips. Details of the experiment; Results and discussion; Conclusions.

A pretreated pencil graphite electrode (PPGE) as an electrochemical sensor was developed and applied to measure diclofenac sodium (DIC). The effects of both potentiostatic and potentiodynamic strategies in the electrochemical pretreatment and performance of the electrode were studied, and it was concluded that the former offers better analytical sensitivity for electroanalytical purposes. PPGE displayed good electrocatalytic activity in comparison to nonpretreated PGE (NPGE). Differential pulse voltammetry (DPV) was used to determine DIC. Therefore, a calibration graph was plotted between the variation of anodic peak currents and the DIC concentration, which was found to be linear in the range 0.23–12.95 μmol/L with the detection limit (S/N = 3) of 0.12 μmol/L. PPGE was utilized to determine DIC in real samples such as biological and pharmaceutical ones, and the good recovery values obtained demonstrated the high accuracy of the modified electrode. [ABSTRACT FROM AUTHOR]

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 E p = +0.59 V and another cathodic at E p = +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. [Display omitted] • First report of electrochemical behavior of benzovindiflupyr. • First electroanalytical method for detection of benzovindiflupyr. • A mechanism for the oxidation of substance was proposed. • The method was successfully applied to smuggled pesticide samples. • Validation was performed using GC-MS. [ABSTRACT FROM AUTHOR]

In the present work, two types of cost-effective bio-electrodes were fabricated by immobilizing Laccase on commercially available pencil graphite leads, and their electro catalytic activity have been examined. The first type of electrode (E 1 ) was fabricated by electro polymerization of polyaniline on pencil graphite leads on which multi walled carbon nanotubes (MWCNT) was immobilized by covalent bonding, while the second type of electrode (E 2 ) was fabricated by direct coating of MWCNT on pencil graphite leads. Two types of bio-cathodes were fabricated by immobilizing Laccase on the two types of electrodes by covalent bonding. The scanning electron microscopy (SEM) revealed three dimensional porous networks providing large surface area for enzyme immobilization. The maximum open circuit potential (OCP) for E 1 and E 2 bio-cathodes were measured 0.58 V and 0.60 V respectively vs Ag/AgCl reference electrode. The maximum current density observed for E 1 and E 2 electrodes were 295.7 μAcm −2 and 228.94 μAcm −2 respectively. Both electrodes exhibited excellent stability, conserving more than 75% of its optimum activity during the period of measurement. [ABSTRACT FROM AUTHOR]

In this study, we have focused on two subjects which are the preparation of a poly(pyrrole-3-carboxylic acid) modified pencil graphite electrode (p(P3CA)/PGE) and the development of a novel sensing strategy for the determination of serotonin (SER) in blood serum and urine samples. This method is based on the electrochemical reduction of oxidation intermediate of SER formed during electrochemical measurements. The characterization of the p(P3CA)/PGE has been performed by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The analytical parameters such as linear range (between 0.01 μM and 1.0 μM), detection limit (2.5 nM according to S / N = 3) and reproducibility (RSD: 3.8% for N : 10) have also been determined. The effects of different substances on the determination of SER have been investigated. The proposed novel sensing method has been successfully tested for the first time in the determination of SER in human blood serum and urine samples. [ABSTRACT FROM AUTHOR]

A novel platinum nanoparticle-modified graphite pencil electrode (PtNP-GPE) for a non-enzymatic determination of H 2 O 2 is proposed. The PtNP-GPE is prepared by heating a GPE in an aqueous solution of ammonium tetrachloroplatinate(II) and ascorbic acid at 75 °C for 15 min. Both unmodified and PtNP-GPE are characterized using field-emission-SEM and cyclic voltammetry. The PtNP-GPE showed better electrocatalytic properties toward the electrochemical redox reaction of H 2 O 2 than that of the unmodified GPE. The PtNP-GPE amperometric response is tested at four different potentials (+0.7, +0.5, −0.2 and −0.3 V vs. Ag/AgCl reference electrode). Taking into consideration both the intensity of the amperometric response and detector stability, the applied potential of +0.5 V is the best among the tested potentials. The PtNP-GPE amperometric response of H 2 O 2 at +0.5 V is linear from 10 to 110 μM ( R 2 = 0.999) with a detection limit of 3.6 μM. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Disposable pencil graphite electrode sensor was developed for the simultaneous detection of HQ and CC. • Satisfactory results were achieved at proposed method in terms of good sensitivity and selectivity. • LOD was found to be 0.85 μM & 0.59 μM for HQ and CC respectively. • Real-world sample analysis was tested for the developed method. [ABSTRACT FROM AUTHOR]