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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]

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]