Showing papers on "Polarography published in 2019"
TL;DR: In this paper, the effect of pH and substituents on electrode reaction have been investigated and discussed and the electrode reaction pathway is found to be H+, e, e, H+ in which the proton uptake precedes the electron transfer.
27 citations
TL;DR: Current developments in the design and applications of electrochemical-based approaches for the determination of the benzodiazepine class of drugs form their introduction in the early 1960s to 2019 are described.
24 citations
TL;DR: An electrochemical dopamine sensor that is based on the use of electrochemically co-reduced graphene oxide (Er-GO) and gold nanoparticles (AuNPs) on an indium-tin oxide (ITO) electrode for voltammetric sensing of dopamine shows an excellent performance under the optimum conditions.
Abstract: The authors describe an electrochemical dopamine sensor that is based on the use of electrochemically co-reduced graphene oxide (Er-GO) and gold nanoparticles (AuNPs) on an indium-tin oxide (ITO) electrode. The synergistic effects of Er-GO and Er-AuNPs promote electron transport in the modified ITO. This results in an excellent performance for voltammetric sensing of dopamine (DA). Under the optimum conditions and a typical working potential of −0.05 V (vs. Ag/AgCl), the ITO electrode has a linear response in the 0.02–200 μM DA concentration range and a low detection limit of 15 nM. The sensor also showed a good selectivity over ascorbic acid and uric acid. The feasibility of the method was studied by analyzing DA in cerebrospinal fluid of rats.
16 citations
TL;DR: In this article, a highly selective method for directly determining the trace Co2+ in highly concentrated zinc electrolyte was proposed, which is based on a second derivative wave of catalytic adsorptive polarography generated by complexing Co2 + with dimethylglyoxime and nitrite onto a dropping mercury electrode.
Abstract: We report herein a highly selective method for directly determining the trace Co2+ in highly concentrated zinc electrolyte. This novel method is based on a second derivative wave of catalytic adsorptive polarography generated by complexing Co2+ with dimethylglyoxime and nitrite onto a dropping mercury electrode. By employing a medium with NH3-NH4Cl buffer, DMG and NaNO2 during determining the trace Co2+, any interferences of highly concentrated Zn2+ and other coexisting metal ions in the electrolyte are completely eliminated due to the selective masking effect of EDTA. When the concentration of Co2+ is within 1.0×10–10–3.2×10–7 mol/L range, it shows a good linear relationship with the current peak. Detection limit is 1.0×10–11 mol/L, and RSD ≤2.7% for six successive assays. We have compared the efficiency of the current method to that obtained by cobalt nitroso-R-salt spectrophotometry, and the absolute values of relative deviations are ≤4.2%. The method developed and described herein has been successfully employed in determining the trace Co2+ in actual zinc electrolyte.
7 citations
TL;DR: Drug determination in rat plasma with good recoveries and low limit of quantitation was done and this technique shows high sensitivity, simplicity and low cost.
Abstract: Aim: Differential pulse polarography was used for the concurrent analysis of the coadministered dantrolene (DAN) and indomethacin (IND) in plasma. Materials & methods: DAN and IND, Hanging mercury ...
7 citations
TL;DR: Differential pulse polarography (DPP) was used for quantification of commercially significant methylbenzotriazole isomers in environmental samples of relevance to wastewater treatment, non-point source pollution and acid mine drainage as discussed by the authors.
Abstract: Because of their persistence and unknown environmental risks, the widespread occurrence of benzotriazoles has been gaining increased attention. A highly selective, rapid, and economical method—differential pulse polarography—was developed and applied for the quantitation of commercially significant methylbenzotriazole isomers in environmental samples of relevance to wastewater treatment, non-point source pollution and acid mine drainage. Differential pulse polarography was able to accurately measure aqueous methylbenzotriazole, as well as the methylbenzotriazole fraction that sorbed to activated sludge biomass, subsurface sediments, and activated carbon. Granular activated carbons were characterized for their ability to sequester benzotriazoles from aqueous environments using differential pulse polarography and high-performance liquid chromatography. Langmuir, Freundlich, Toth and Redlich–Peterson isotherm models were compared for their ability to describe benzotriazole partitioning to granular activated carbons under a relatively wide range of water quality conditions. Sorption behavior of 5-methylbenzotriazole was best-described by a Redlich–Peterson isotherm model, where water quality parameters were varied in the following range pH (1 < pH < 5), temperature (5 °C < T < 25 °C), and in the following ranges of an ionic strength (0.005 < M < 0.02). 4- and 5-methylbenzotriazole concentrations determined by differential pulse polarography correlated well with those concentrations measured by high-performance liquid chromatography through an environmentally significant range (0.4–30 mg/L). Using a static mercury drop electrode, the method detection limit was 50 and 40 μg/L for 4- and 5-methylbenzotriazole, respectively. The developed DPP polarographic method was found to be simple, rapid, and it can be applied directly to environmental samples without filtration, extraction, and centrifugation.
7 citations
TL;DR: In this paper, a reliable differential pulse polarographic (DPP) method has been developed and applied for the determination of ibuprofen IBU in dosage form with dropping mercury electrode (DME) versus Ag/AgCl.
Abstract: A reliable differential pulse polarographic (DPP) method has been developed and applied for the determination of ibuprofen IBU in dosage form with dropping mercury electrode (DME) versus Ag/AgCl. The best peak was found at cathodic peak of -1.18 V in phosphate buffer at pH=4 and 0.025M of KNO3 as supporting electrolyte. In order to obtaine the highest sensitivity, instrumental and experimental parameters were examined including the type and concentration of supporting electrolyte, pH of buffer solution, pulse amplitude and voltage step time. Diffusion current showed a direct linear relationship to ibuprofen concentration in the range of (5 – 30) μg. mL-1 (2.43× 10-5 – 1.45 × 10-4 mol·L–1) with correlation coefficient r= 0.9999, detection limit (S/N = 3) =3.40 μg. mL-1 (1.65 × 10-5 mol·L–1) and the value of precision in terms of relative standard deviation RSD%, ranged between 0.374-0.5176 %. The established DPP method offers an excellent analytical figure of merits as well as its successful applicability to examine two commercial drug forms (tablet and suspension) for the determination of ibuprofen.
5 citations
TL;DR: In this paper, a nano-carbon ionic liquid electrode modified with palladium-doped graphene (Pd-GR/nano-CILE) was used for electrochemical analysis of dopamine (DA) and uric acid (UA).
Abstract: We described a nano-carbon ionic liquid electrode modified with palladium-doped graphene (Pd-GR/nano-CILE) for electrochemical analysis of dopamine (DA) and uric acid (UA). The surface morphologies of the electrodes and palladium-doped graphene (Pd-GR) were observed by scanning electron microscopy and transmission electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy were used for investigating the electrochemical properties of the proposed sensor. The oxidation peaks of DA and UA were well separated at the Pd-GR/nano-CILE using differential pulse voltammetry. The sensor displayed good electrocatalytic activity toward DA and UA with increased peak currents and reduced peak potentials compared with conventional carbon paste electrode. Under optimal conditions, linear calibration plots for the analysis of DA and UA were obtained in the range of 5–200 μM, respectively. The detection limits (at an S/N ratio of 3) were 0.5 μM for DA and 0.8 μM for UA. The method was successfully applied to the determination of DA and UA in spiked human urine and serum samples.
5 citations
TL;DR: In this article, the influence of adding transition metal, Ni(II), to the electrolyte containing VAL, on the voltammetric response was studied, and a simple cleanup procedure was applied for urine samples that involves the use of solid phase extraction with the elution of VAL with methanol.
Abstract: Valsartan (VAL) can be analyzed at the mercury electrode in the presence of nickel (II) yielding a sensitive cathodic peak at − 0.7 V which may be attributed to the reduction of the complex formed between nickel and VAL. Low LOD and LOQ were achieved (7.6 and 23 nM, respectively) permitting the analysis of VAL not only in its pharmaceutical formula, but also in human urine. The influence of adding transition metal, Ni(II), to the electrolyte containing VAL, on the voltammetric response was studied. Differential-pulse voltammetry, using working electrode: hanging mercury drop electrode (HMDE), was applied to elucidate and confirm the possible complexation reaction that could occur between VAL and nickel which aids in the determination of VAL in tablets and human urine. A simple cleanup procedure was applied for urine samples that involves the use of solid-phase extraction with the elution of VAL with methanol. The polarographic peak, which corresponds to the reduction of Ni(II) in the formed complex with VAL, was a function of the concentration of VAL, pH of the medium and Ni(II) concentration at the electrode surface. At Britton–Robinson buffer pH 6 and using 800 µM Ni(II), the reduction peak current linearly varied with the VAL concentration over the ranges of 25–150 and 25–200 nM in tablets as well as urinalysis, respectively.
4 citations
TL;DR: Differential pulse polarography was performed with a dropping carbon fluid electrode (DCFE) for the periodic renewal of DCFE, a new type of drop knocker was devised in this article.
3 citations
26 Mar 2019
TL;DR: In this article, the interval of potentials of cathodic reduction of perrhenate ions in alkaline electrolytes was established using cyclic voltammetry, and a scheme of the cathodic process was proposed which includes electrode, chemical and adsorption stages.
Abstract: Relevance. Rhenium and its alloys are refractory, heat-resistant, high-temperature, and corrosion-resistant materials which are used in aircraft and rocket engineering, electrical engineering, in production of catalysts. Rhenium belongs to rare elements, this necessitates the improvement of technological processes for its extraction from natural raw materials and waste materials, as well as improving the accuracy of analytical methods for its determination. Electrochemical methods are optimal in terms of cost, expressiveness and availability for analysis and processing of rhenium-containing raw materials. In this regard, the study of the regularities of the electrode processes involving rhenium and its compounds is relevant. The aim of the research is to establish the sequence of cathodic reduction of perrhenate ions in alkaline electrolytes. Objects: ammonium perrhenate solutions, sodium hydroxide solutions. Methods: direct and alternating current polarography, cyclic voltammetry, accumulative potentiostatic electrolysis. Results. The authors have determined the interval of potentials of cathodic reduction of ReO4– ions (1×10–5…1×10–2 М) in alkaline medium (1...10 M NaOH) at mercury electrodes is –1,25…–1,75 V (sat. Ag/AgCl/KCl). A significant contribution of catalytic and adsorption current components to the total value of cathodic current was established on the basis of temperature dependence of limiting current and current dependence on height of dropping Hg-electrode column. A sequence for reduction of ReO4– in alkaline electrolytes was established using cyclic voltammetry, and a scheme of the cathodic process was proposed which includes electrode, chemical and adsorption stages. Experimental data on potentiostatic electrolysis and on voltammetry of chemically synthesized ReO2 were used to interpret the polarographic results. The paper demonstrates the importance of the obtained results for analytical determination of rhenium.
TL;DR: In this paper, the behavior of the electrode reaction of some arylazomethine-1,2,3-triazole derivatives via convolutive sweep voltammetry, chronoamperometry and differential pulse polarography techniques in Britton Robinson universal aqueous buffer series with pH in the range of 2.4-11.8, at mercury electrode (HMDE).
Abstract: Herein this work, summarize the behavior of the electrode reaction of some arylazomethine-1,2,3-triazole derivatives via convolutive sweep voltammetry, chronoamperometry and differential pulse polarography techniques in Britton Robinson universal aqueous buffer series with pH in the range of 2.4–11.8, at mercury electrode (HMDE). The evaluation of the important kinetics criteria of arylazomethine-1,2,3-triazole derivatives was performed experimentally in Britton Robinson universal buffer solutions. The electrons which participate in the electrode reaction of arylazomethine-triazole derivatives were calculated using controlled potential coulometry. Theoretical cyclic sweep voltammograms were generated via software of digital simulation for testing the accuracy of the experimental chemical and electrochemical criteria. The good comparison between the generated and experimental cyclic sweep voltammograms confirms the accuracy of the electrochemical parameters and the proposed electrode mechanism. A good agreement between the theoretical voltammograms and the experimental one of EqCirr model of the 3-((1H-1,2,3-triazol-4-ylimino)methyl)phenol derivative (1) at pH 3.2 and a scan rate of 1000 mVs-1 is shown in the following figure. The obtained theoretical and experimental chemical and electrochemical parameters confirm the accuracy of the proposed mechanism.