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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]

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]

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]

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]

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 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]

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 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]