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A procedure to analyze pH-dependent complex formation equilibria from cyclic voltammetry is described. Application to adduct formation equilibria between [Fe(CN) 6 ] 4- and [Fe(CN) 6 ] 3- with different polyammonium receptors is discussed. Extension to the interaction of substrates such as ATP, NAD + , NADP + , and carboxylate ions with these...
A benzoquinone modified basal plane pyrolytic graphite electrode shows electrocatalytic activity for the oxidation of NADH and ascorbic acid in phosphate buffer (pH 7.3). The modified electrode shows a linear variation of catalytic current with concentration in the range 1-10 mM for both NADH and ascorbic acid. The rate constants have been estimated from the surface coverage data.
The adsorption properties of dioxouranium (II)-Phathalate complexes onto hanging mercury drop electrode are exploited in developing a highly sensitive and selective stripping voltammetric procedure for the determination of uranium (VI). The reduction current of adsorbed complex ions of U(VI) was measured by both linear sweep (LSCSV) and differential pulse cathodic stripping voltammetry (DPCSV), preceded...
Cobalt-cyanometallate films electrochemically deposited on a platinum electrode were studied by cyclic voltammetry (CV), in-situ FTIR spectroelectrochemistry (FTIRs) and potential resolved XPS measurements. The experimental results reveal that the CoHCF film on Pt electrode exists in two forms. The major form of the inner layer of the film is (M + ) 2 Co(II)Fe(II)(CN) 6 where...
The electrochemistry of dopamine (3-hydroxytyramine) was studied by cyclic voltammetry at a glassy carbon electrode in the presence of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) micelles at different pH. The anodic peak potential (E pa ) and peak current (I pa ) were found to be remarkably dependent on the charge and the concentration of the surfactant...
A method for the determination of the major serotonin metabolite - 5-hydroxyindole-3-acetic acid (5-HIAA) in human gastric juice by cyclic voltammetry was described. The measurement conditions were investigated. The potential window was chosen from +0.1 to +0.9 V, the supporting electrolyte was 0.025 M PBS solution (pH 2.0). The method allowed determination in the concentration range from 2.0 x10...
(C 70 ) 2 -p-tert-butylcalix[6]arene complex films on GC electrode surface showed two couples of redox reactions in mixed solvent of (1:1, v:v) acetonitrile and water containing tetra-butylammonium perchlorate. The electrocatalytic reduction for nitrite by these films was observed, indicating that (C 70 ) 2 -p-tert-butylcalix[6]arene is capable of mediating...
The electrochemistry of l-tyrosine was studied by cyclic voltammetry at a glassy carbon electrode. Although l-tyrosine itself showed very poor electrochemical response, the response could be greatly enhanced by using 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy (HO-TEMPO) as a mediator that enables a sensitive determination of the substrate. An electrocatalytic EC' mechanism with the oxoammonium...
The C 60 -[dimethyl-(β-cyclodextrin)] 2 and nafion chemically modified electrode (CME) exhibits one electroreduction peak and two electro-oxidation peaks in a mixed solvent of water and acetonitrile (3:2, v/v) containing tetra-butylammonium perchlorate. The reduction of chloroacetic acids (mono-, di- and tri-) can be electrocatalyzed at this electrode, indicating that C 6...
Electrochemical investigation of the interaction of rutin (Rt) with hemoglobin (Hb) at a glassy carbon electrode is reported for the first time. With the addition of hemoglobin in a rutin solution, both the reduction and oxidation currents decrease with few changes in the peak potentials. The reaction of rutin with hemoglobin forms a nonelectroactive supramolecular complex Hb-Rt. The equilibrium constant...
Voltametric and coulometric methods have been used to study the electroanalytical behaviour of 3,8-difluorobenzo[c]cinnoline. The number of electrons transferred, the wave characteristics, diffusion coefficient and reversibility of the reactions have been investigated in ethyl alcohol-BR. Adsorption of the molecule on the surface of the mercury drop electrode was analyzed and this phenomena was exploited...
The thiolactic acid (TLA) self-assembled monolayer modified gold electrode (TLA/Au) is demonstrated to catalyze the electrochemical response of norepinephrine (NE) by cyclic voltammetry. A pair of well-defined redox waves were obtained and the calculated standard rate constant (k s ) is 5.11x10 -3 cm s -1 at the self-assembled electrode. The electrode reaction is...
The self-assembled electrode with the homocysteine monolayer (Hcy/Au) has been characterized by infrared spectroscopy and ac impedance spectroscopy in electrolyte. The Hcy/Au electrode is demonstrated to promote the electrochemical response of epinephrine (E) by cyclic voltammetry. A pair of well-defined redox waves was obtained and the calculated standard rate constant (k s ) is 2.1x10 ...
A low-cost electrochemical flow-through cell is designed and fabricated to use in conjunction with a flow injection (FI) system. This detector cell used a centrosymmetric radial flow thin-layer geometry with a stainless steel auxiliary electrode and a reference electrode (Ag/AgCl) without a salt bridge. The 5H pencil lead electrode used as a working electrode in the home-made cell is an extremely...
The electroanalysis of d-penicillamine in 0.1 phosphate buffer (pH 7) was studied at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry as a function of concentration of analyte and pH of analyte solution. Comparison experiments were performing using a glassy carbon (GC) electrode. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, but the GC...
Electrochemistry and electrocatalysis of binuclear cobalt phthalocyaninehexasulfonate sodium salt (bi-CoPc) were investigated successfully in liquid crystal films of didodecyldimethylammonium bromide (DDAB) on pyrolytic graphite (PG) electrodes in aqueous solution. This new bi-CoPc-surfactant film modified electrode could reduce aggregation of bi-CoPc in aqueous solution, which was confirmed by the...
The electrochemical oxidation of salicylic acid (SA) has been studied on a glassy carbon electrode using cyclic voltammetry and differential pulse voltammetric (DPV) method. SA gives a single irreversible oxidation wave over the wide pH range studied. The irreversibility of the electrode process was verified by different criteria. The mechanism of oxidation is discussed. Using differential pulse voltammetry,...
Cytochrome P450sccK201E, mutated form of cytochrome P450scc native recombinant (P450sccNR), was employed to study the enzyme-substrate interaction. The detection of the cholesterol was performed by electrochemical method using cyclic voltammetry (CV) and chronoamperometry measurements. The biochemical analysis was realized to observe the electrochemical responses of the engineerized enzyme to three...
The use of 3-indoxyl phosphate (3-IP) as an electrochemical substrate for ELISAs with voltammetric detection was investigated. Indirect measurements of alkaline phosphatase (AP) and horseradish peroxidase (HRP) activity in solution were carried out. Picomolar levels of both enzymes can be detected, which enables the design of electrochemical immunoassays using this substrate. The enzymatic turnover...
The cyclic voltammograms of levonorgestrel (LNG) in Britton-Robinson buffers of pH 2-11 at the hanging mercury drop electrode showed a single two-electron irreversible cathodic peak over the whole pH range. This peak may be attributed to the reduction of the 3-keto-delta-4-group in the A-ring of the LNG molecule. The interfacial adsorptive character of levonorgestrel onto the surface of the hanging...
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