New applications of boron-doped diamond electrode for voltammetric determination of ascorbic acid

An unmodified boron-doped diamond electrode was used for the voltammetric determination of ascorbic acid (AA). The measurements were carried out in an acetate buffer solution of pH = 4.6 by differential pulse voltammetry (DPV). Under the optimized experimental conditions, AA gaves linear response in a broad concentration range from 5 · 10–7 to 2· 10–3 mol/dm3. The detection limit was 1.63 · 10–7 mol/dm3. The proposed procedure was applied for simple and fast voltammetric determination of ascorbic acid in human urine samples and commercially available dietary supplements

The simultaneous voltammetry determination of cadmium(II) and lead(II) at bismuth film glassy carbon electode prepared with the use of mediator

This paper shows a novel, simple and rapid voltammetric procedure, which enables Cd and Pb determination at traces concentrations. All measurements were carried out by differential  pulse anodic stripping voltammetry (DPASV) with total time of analysis of 210 s. The obtained detection limits were 8.46 · 10-10 mol L-1 and 2.57 · 10-10 mol L-1  for Cd(II) and Pb(II), respectively. This procedure was successfully applied for the quantification of mentioned metal ions in water samples collected from the Vistula River

The Influence of Protonation on the Electroreduction of Bi (III) Ions in Chlorates (VII) Solutions of Different Water Activity

We examined the electroreduction of Bi (III) ions in chlorate (VII) solutions under varied protonation conditions of the depolariser using voltammetric and impedance methods. The results of the kinetic parameter correlation lead to the statement that the changes in the amount of chloric (VII) acid against the amount of its sodium salt in the supporting electrolytes of the low water activity have a significant influence on the rate of Bi (III) ion electroreduction. The increase of the concentration of chloric acid sodium salt, aswell as the chloric (VII) acid alone within the particular concentration of the supporting electrolyte, inhibits the process of Bi (III) ion electroreduction. It should be associated with the reorganisation of the structure of the double layer connected with the slow dehydration inhibited by ClO 4 − ions. The standard rate constants ks values with the increase of the chlorate (VII) concentrations for all the solutions examined of chlorates (VII) confirms the catalytic influence of the decrease of water activity on the process of Bi (III) ion electroreduction. The multistage process is confirmed by the non-rectilinear 1nkf=f(E) dependences

Sensing of formetanate pesticide in fruits with a boron-doped diamond electrode

This study describes the development of a simple and accurate methodology for carbamate pesticide formetanate (FMT) analysis in fruits based on the use of a boron-diamond doped electrode (BDDE) cathodically pretreated and on the forward component of the current of square-wave voltammetry (SWV). FMT exhibits a well-defined irreversible oxidation process, which reaction mechanism is diffusion-controlled, involves the participation of one electron and is influenced by the electrolyte pH. However, protonation does not participate in the rate-determining step in the redox process. The optimum experimental and voltammetric conditions were pH 7.0 (0.04 mol L−1 Britton-Robinson buffer), pulse potential frequency of 20 s−1, amplitude of the pulse of 25 mV, and height of the potential step of 3 mV. Under the optimum conditions, calibration curve was linear from 4.98 × 10−7 to 1.70 × 10−5 mol L−1 FMT with a limit of detection of 3.7 × 10−7 mol L−1. FMT sensing was performed in different fruits (mango and grape). Recoveries ranged from 95.2 ± 2.8 to 104.0 ± 3.5% for mango and 96.5 ± 2.5 to 105.2 ± 3.5% for grape proving the accuracy and precision of the electroanalytical methodology. The attained data validated the applicability of the developed approach for FMT quantification in fruits.info:eu-repo/semantics/publishedVersio

Modified Mesoporous Carbon Material (Pb-N-CMK-3) Obtained by a Hard-Templating Route, Dicyandiamide Impregnation and Electrochemical Lead Particles Deposition as an Electrode Material for the U(VI) Ultratrace Determination

In this paper, a dicyandiamide-impregnated mesoporous carbon (N-CMK-3), electrochemically modified in situ with lead film (Pb-N-CMK-3), was tested as an electrode material for U(VI) ultratrace determination. The prepared carbon material was characterized by XRD, SEM-EDX, Raman, FT-IR, XPS analysis and nitrogen sorption measurements. The changes of electrochemical properties of glassy carbon electrodes (GCE) after the N-CMK-3 and Pb-N-CMK-3 modification were studied using CV and EIS methods. The modification of the GCE surface by the N-CMK-3 material and Pb film increases the electroactive area of the electrode and decreases the charge transfer residence and is likely responsible for the electrochemical improvement of the U(VI) analytical signal. Using square-wave adsorptive stripping voltammetry (SWAdSV), two linear calibration ranges extending from 0.05 to 1.0 nM and from 1.0 to 10.0 nM were observed, coupled with the detection and quantification limits of 0.014 and 0.047 nM, respectively. The Pb-N-CMK-3/GCE was successfully applied for U(VI) determination in reference materials (estuarine water SLEW-3 and trace elements in natural water SRM 1640a)

The lead film electrode prepared with use of the combination of ex-situ and in-situ methods in stripping analysis of folic aci

In this article, elaboration of a "hybrid" lead film electrode is reported. The strategy to create such an electrode is based on the combination of ex-situ and in-situ plating methods and also the use of a reversibly deposited metal mediator (Cd) for the lead film formation. Various plating conditions, which influenced the response of the “hybrid” lead film electrode to folic acid, were thoroughly optimized and discussed. The results have indicated that the sensitivity of the “hybrid” lead film electrode prepared with use of the metal mediator was remarkably improved compared to the in-situ and ex-situ plated lead film electrodes, and the “hybrid” lead film electrode prepared without use of the metal mediator could be applied to the determination of folic acid in tablets (preparative Folovit®) with satisfactory results

Voltammetric screen-printed carbon sensor modified with multiwalled carbon nanotubes and bismuth film for trace analysis of thallium(I)

The paper investigates the possibility of using commercially available screen-printed sensors with carbon nanomaterials modified working electrodes to anodic stripping voltammetric determination of trace concentrations of Tl(I). Each working electrode was additionally plated in-situ with a bismuth film (BiF). The highest analytical signal of Tl(I) at potential of -0.65 V (vs. pseudo- reference silver electrode) was achieved at the screen-printed carbon sensor with multiwalled carbon nanotubes and bismuth film modified working electrode (SPCE/MWCNTs/BiF). The calibration curve was linear in the range of Tl(I) concentrations from 1·10-8 to 1·10-6 mol·dm-3 (-0.9 V, 180 s). The developed procedure of Tl(I) determination at this sensor allowed to achieve the low limits of detection and quantification of Tl(I), 2.8·10-9 and 9.3·10-9 mol·dm-3 respectively. The method was used to determine thallium in the spiked water samples from the Vistula river