جستجوی مقالات مرتبط با کلیدواژه "differential pulse" در نشریات گروه "شیمی"

Cobalt ferrite nanoparticles (CFNs) were successfully synthesized by a wet chemical method. The morphology and that of the crystal structure of the synthesized nano ferrites was done by X-ray diffraction analysis and Transmission electron microscopy techniques. The crystalline size of the synthesized nanoparticles was in the range of 30 nm calculated by the Debye-Scherrer equation. A glassy carbon electrode (GCE) modified with the ferrite nanoparticles (CFNs) was employed for the electrochemical detection of dopamine using the techniques of cyclic voltammetry and differential pulse voltametry. The chemically modified electrode exhibited exceptional redox action for the detection of dopamine (DA), with a notable decline of overpotential while compared to bare GCE. The CFNs/GCE exhibited excellent stability, reproducibility and sensitivity in the determination of DA with a detection limit of 0.2 μm. The sensor exhibited appreciable electrocatalytic behavior in the simultaneous detection of ascorbic acid (AA), Dopamine (DA) and Uric acid (UA).

In this work, a selective and sensitive method to the determination of essential elements Cu and Zn in drinking water proposed by adsorptive stripping differential pulse cathodic voltammetry (AdSDPCV) using Alizarin (AZ) as a ligand. The complexes of metals-AZ were deposited onto a hanging mercury drop electrode (HMDE) and the resulting current was analyzed. Increase peak current of metals-AZ obtained optimization condition of pH 6, AZ concentration0.04 mmol/L, supporting electrolyte concentration0.5 mol/L, potential for adsorptive deposition (Eads) -0.1 V, the time for adsorptive deposition (tads)70 s, respectively, the instrumental parameters (drop size of mercury 8 and scan rate 800 ms/V). The linearity of metals were160 ng/L and 200 ng/L, the limit of detection 0.1 ng/L for Cu and 0.05 ng/L for Zn, respectively. Relative standard deviation (RSD) 0.5% for Cu and 0.7% for Zn and recovery Cu and Zn in the range 98 to 101%, respectively. The applicability of AdSDPCV methods is successfully for determination of metals in drinking water.

Electrochemical oxidation behavior of ritodrine hydrochloride (RT.HCl) was studied in Britton Robinson buffer at different pH range from 2 to 10 using carbon paste (CPE), modified zirconium oxide carbon paste (ZrO2-MCPE), graphite pencil (GPE) and glassy carbon electrodes (GCE). Cyclic voltammetry (CV) was showed one well-defined, irreversible, diffusion-controlled anodic peak at pH 9 by using CPE and GPE electrodes and pH 8 and 7 at ZrO2-MCPE and GCE electrodes, respectively. The linear response was obtained in the concentration range of 3.33×10-6-4.33×10-5, 6.67×10-8-7.33×10-7, 4.0×10-66×10-5 and 5.0×10-6-4×10-5 M with detection limit (LOD) of 1.57×10-6, 6.18×10-8, 1.71×10-6 and 3.32×10-6 mol L-1 by using differential pulse voltammetric method (DPV) at CPE, ZrO2MCPE, GPE and GCE, respectively. The linear concentration response was obtained in the concentration range of 1.33×10-6-1.47×10-5, 3.33×10-8-3.67×10-7, 4.0×10-6-5.5×10-5 and 5.00×10-6-4.5×10-5 M with detection limit (LOD) 5.78×10-7, 1.11×10-8, 1.74×10-6 and 1.84×10-6 mol L-1 by using square wave voltammetric method (SWV) at CPE, ZrO2-MCPE, GPE and GCE, respectively. The repeatability and reproducibility of the method were 0.411.27, 0.25-1.11, 0.49-1.86 and 0.73-2.13% relative standard deviations (RSD) for anodic peak current by using square wave voltammetric method (SWV) at CPE, ZrO2-MCPE, GPE and GCE electrodes. The mechanism successfully confirmed by molecular orbital calculation (MOC). These calculations give the bond order, bond length and charge distribution. This helps the successful choice of the weakest bond which changed during oxidation or reduction. Therefore, the best pathway for the oxidation of this drug is correctly selected for proposed mechanism.