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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]

Para-nitrophenol (PNP) is a toxic compound that enters the environment during manufacturing and processing of a variety of industrial products. In this work, we present a study on the electrocatalytic reduction of PNP to p-hydroxyl aminophenol in aqueous solutions using metallic gold electrode. p-Hydroxyl aminophenol has been used abundantly as a model substance to check the catalytic activity of metallic gold electrode. Here, we present a full kinetic scheme that includes the intermediate p-Hydroxyl aminophenol. The discussion of the resulting kinetic equations shows that the reduction of PNP at the surface of metallic gold electrode is a diffusion transfer process and irreversible. The analytical performance was also evaluated with respect to PNP concentration, and other variables. A linear calibration graph was obtained in the concentration range from 5.0 × 10−7 to 5.0 × 10−3 mol L−1 PNP. The detection limit was found to be 5.0 × 10−7 mol L−1. For eight tests, the differential pulse response was reproduced with 1.9% relative standard deviation at 5.0 × 10−6 mol L−1 PNP in acetate buffer solution. [ABSTRACT FROM AUTHOR]

The voltammetric behavior of mercury was investigated using carbon paste electrode modified with a palladium oxide supported onto natural phosphate (PdO/NP-CPE). The aim of this work is to optimize all factors influencing this determination (frequency, amplitude, pulse height, deposition time and potential, heated temperature and charge loading of palladium oxide). The best results were obtained with square wave potential in 0.1 mol/L HCl medium. Linear dependence of current versus mercury(II) concentrations, under optimized conditions, was obtained for the concentration ranges from 2.5 × 10 −7 to 1.0 × 10 −4 mol/L. For 3 min preconcentration, detection limits of 1.93 × 10 −8 mol/L was obtained at the signal noise ratio (SNR) of 3. The repeatability expressed as relative standard deviation (%R.S.D.) was always <4.78%. These results indicate clearly that using square wave voltammetry (SWV) with the PdO-doped natural phosphate–carbon composite electrode provides a real opportunity for detecting mercury(II) in ambient water solutions. [ABSTRACT FROM AUTHOR]

In this paper, we report a synthesis of a new lacunar apatite, KCdPb 3 (PO 4 ) 3 , using solid state method, and its application as modifier of carbon paste electrode (KLA-CPE) to determine mercury (II). Sodium replacement with potassium induced a linear variation of the crystallographic parameters a and c according to Vegard's law and led to amplify the electrical signal of the working electrode. The peak currents of mercury (II) increased linearly with their concentration at the range from 2.0×10 −7 mol L −1 to 1.0×10 −4 mol L −1 using differential pulse anodic stripping voltammetry. The detection limit was found to be 1.11×10 −8 mol L −1 . The use of this electrochemical sensor has been successfully implemented for the determination of Hg (II) in seawater and fish samples. The obtained results were found to be very satisfactory. [ABSTRACT FROM AUTHOR]

A sensitive, selective and reproducible electrochemical method has been established for the electroanalysis of 4-nitroaniline (4-NA) using a carbon paste electrode modified with a chitosan solution gelled in acetic acid (CS@CPE). The modified electrode was then characterized spectroscopically using Fourier Transform Infrared (FTIR) spectroscopy. In addition, the electrochemical and interfacial characteristics of the as-prepared modified electrode were assessed by potentiodynamic cyclic voltammetry (CV) and AC electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was additionally used to deduce the trace amounts of (4-NA) in phosphate buffered saline (PBS) of pH 7.0 as an ideal electrolyte. Under optimized conditions, the peak current of 4-NA increased linearly with the increasing 4-NA concentration over the range of 0.1 μM to 0.1 Mm. The calibration curve presents two linear ranges of current versus 4-NA concentration with a detection limit of 93.4 nM (3sb / B). The repeatability of the current peak registered at CS@CPE was performed at a level of 0.5 μM 4-NA employing one sensor on the same day for eight measurements. The relative standard deviation was 3.5%. Unlabelled Image • CS@CPE was used to detect 4-nitroaniline by differential pulse voltammetry. • All experimental parameters that affected 4-NA detection were optimized. • The results indicated the feasibility to determine 4-NA in wastewater. [ABSTRACT FROM AUTHOR]

The electrochemical oxidation of ibuprofen was investigated at a montmorillonite-doped carbon paste electrode (Mt–CPE). A well-defined oxidation peak was observed at around 1.02 V/AgCl in phosphate buffer (pH 8). The experimental condition was optimized by varying chemical and electrochemical parameters. The oxidation peak current is linear to the ibuprofen concentration in the ranges 1.0 × 10 − 3 –1.0 × 10 − 6 mol L − 1 and 1.0 × 10 − 6 − 1.0 × 10 − 7 mol L − 1 with a detection limit of 6.80 × 10 − 8 mol L − 1 . The precision (n = 8) assessed as relative standard deviation (R.S.D.) were 1.24% for 1.0 × 10 − 6 mol L − 1 and 1.07% for 4.0 × 10 − 5 mol L − 1 respectively. Possible interferences were tested and evaluated in 1.0 × 10 − 5 mol L − 1 ibuprofen in the presences of common organic and inorganic interfering agents. Based on its high sensitivity and good selectivity, the Mt–CPE was successfully applied to determine ibuprofen in river water and commercial tablets. The satisfactory obtained results confirm the applicability of this sensor in practical analysis. [ABSTRACT FROM AUTHOR]