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Linear Sweep Voltammetry (linear + sweep_voltammetry)
Selected AbstractsSilver Doped Poly(L -valine) Modified Glassy Carbon Electrode for the Simultaneous Determination of Uric Acid, Ascorbic Acid and DopamineELECTROANALYSIS, Issue 5 2010Wenna Hu Abstract In this paper, a silver doped poly(L -valine) (Ag-PLV) modified glassy carbon electrode (GCE) was fabricated through electrochemical immobilization and was used to electrochemically detect uric acid (UA), dopamine (DA) and ascorbic acid (AA) by linear sweep voltammetry. In pH,4.0 PBS, at a scan rate of 100,mV/s, the modified electrode gave three separated oxidation peaks at 591,mV, 399,mV and 161,mV for UA, DA and AA, respectively. The peak potential differences were 238,mV and 192,mV. The electrochemical behaviors of them at the modified electrode were explored in detail with cyclic voltammetry. Under the optimum conditions, the linear ranges were 3.0×10,7 to 1.0×10,5,M for UA, 5.0×10,7 to 1.0×10,5,M for DA and 1.0×10,5 to 1.0×10,3,M for AA, respectively. The method was successfully applied for simultaneous determination of UA, DA and AA in human urine samples. [source] Development of a Rapid Single-Drop Analysis Biosensor for Screening of Phenanthrene in Water SamplesELECTROANALYSIS, Issue 20 2004Abstract Detection techniques for biosensors often require bulky instruments or cells that are not feasible for in-field analysis. Our single-drop cell design, optimized in this work, comprised a screen-printed three-electrode (SPE), strip in horizontal position onto which a volume of 100,,L of sample or substrate solution was placed to ensure electrical contact (complete circuit). Together with optimized linear sweep voltammetry (LSV), parameters for the detection of the enzyme alkaline phosphatase (AP), the system was applied to a biosensor for the analysis of polycyclic aromatic hydrocarbons (PAHs), in environmental samples. A limit of detection (LOD), of 0.15,ppb was achieved for a model system with an IC50 value of 0.885 ppb and a linear range (LR), of 0.2,10,ppb. Application of the single drop analysis (SDA), format to a PAH biosensor gave a LOD of 1.4,ppb for detection of phenanthrene with an IC50 value of 29.3,ppb and linear range of 2,100,ppb. Proof of concept is shown with spiked sample analysis of phenanthrene in matrices such as sea, river and tap water. [source] Evaluation of antioxidant properties of dermocosmetic creams by direct electrochemical measurementsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2005C. Guitton Cyclic voltammetry and linear sweep voltammetry were preliminarily used in order to evaluate the global antioxidant properties of dermocosmetic creams. Experiments were performed by introducing electrodes directly into the creams without any pretreatment of the samples. Current,potential curves showed significant anodic current depending on the antioxidant-containing cream studied. In comparison, little amperometric response was recorded with an antioxidant-free cream base. Aqueous solutions of the corresponding antioxidants showed analogous anodic waves and similar peak potentials. A correlation between the global anodic peak and the presence of the antioxidant species in the cream was made with eleven skin creams, attesting to the reliability of the method. Among the tested electrode materials, platinum gave the best results in terms of electrochemical kinetics and measurement precision (current peak standard deviation <5%). Exposure of a depilatory cream to oxidizing agents (e.g. hydrogen peroxide, air, or light) caused a decrease in peak current as expected. This methodology enabled us to evaluate the evolution of the total antioxidant capacity under oxidative stress and gives encouragement to further development of a voltammetric method to quantify cream antioxidant power. [source] Construction of a novel sensor based on electropolymerization of carmine for voltammetric determination of 4-nitrophenolJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2007Chunya Li Abstract 4-Nitrophenol (4-NP) has been determined with voltammetric technique based on a novel sensor fabricated by electropolymerization of carmine on a glassy carbon electrode (GCE). An obvious reduction peak located at about ,0.700 V and a couple of redox peaks that were not well-defined were observed in the potential range of ,1.00 to 0.600 V. Compared with its voltammetric behavior on a bare GCE, the reduction peak potential shifted positively and the peak current increased significantly. All experimental parameters were optimized and linear sweep voltammetry was proposed for its determination. In the optimal conditions, the reduction peak current was proportional to the 4-NP concentration over the concentration range from 5.00 × 10,8 to 1.00 × 10,5 mol L,1, and the detection limit was 1.00 × 10,8 mol L,1 after 200 s of accumulation. The high sensitivity and selectivity of the sensor was demonstrated by its practical application for the determination of trace amounts of 4-NP in lake water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3271,3277, 2007 [source] Electrochemical study on interaction of vincristine with tubulinCHINESE JOURNAL OF CHEMISTRY, Issue 11 2001Yong Yu Abstract In Tris (0.005 mol/L)-NaCl (0.05 mol/L) buffer solution (pH = 7.10), keeping temperature at 37°C, a highly sensitive reduction peak of the antitumor agent was obtained by linear sweep voltammetry. The peak potential is-1.56 V (vs. SCE). The peak current is proportional to the concentration of vincristine over the range of 2.1 ± 10,7 -4.2 ± 10,6 mol/L with the detection limit of 1.0 ± 10,7 mol/L. The behavior of the binding of vincristine to tubulin was studied. The results showed that the reaction of tubulin dimer with vincristine formed an electrochemically active complex to be 1:2. Its stability constant is 2.5 ± 1014. The reduction process of the complex is irreversible with adsorptive characteristics. [source] | ||||||||||