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Voltammetric determination of nitrite in meat products using polyvinylimidazole modified carbon paste electrode

A simple and sensitive voltammetric method was developed to determine the amount of nitrite by using Carbon Paste Electrode (CPE) which is modified with polyvinylimidazole (PVI). A buffer solution of phosphate with a pH 4 value was used in the experiments. The amount of the nitrite-ion was determined by cyclic voltammetry (CV). The electro-chemical behaviour of nitrite-ion was investigated by using CV on the PVI modified CPE. A well-defined oxidation peak was obtained at 0.83 V against a reference Ag/AgCl electrode. Differential pulse voltammetry (DPV) was applied for the calibration plot and for the detection limit. The optimisation procedure was done in two steps: using a two-level factorial design for preliminary evaluation of the contributing factors, and the Box-Behnken Design (BBD) to assess the optimal experimental conditions. These are done with the analysis of 3 different factors in 15 runs of DPV. The optimum conditions are obtained within a linear response range of 5×10(-7)-1×10(-4) mol L(-1). Regression analysis is performed within this range showed the linear equation of y=0.028x+3.93×10(-7) with r(2)=0.9982, and for n=7. Limit of Detection (LOD) was 9×10(-8) mol L(-1) with S/N=3, and Limit of Quantification (LOQ) was 3×10(-7) mol L(-1) with S/N=10. The procedure was used successfully to detect the amount of nitrite in meat products.

Electrochemically prepared acrylamide/N, N'-methylene bisacrylamide gels

Acrylamide/N,N′-methylene bisacrylamide gels were synthesized electrochemically at room temperature in the presence of an initiator only, without using chemical activator. Various electrode systems were examined and silver was chosen as a working electrode material. Working conditions were determined and the effect of bisacrylamide concentration and electrode voltage on gelation times was examined.

Dielectric spectroscopy study of EMA-EGDM crosslinking system at sol-gel transition

Ethyl methacrylate, ethylene glycol dimethacrylate free radical crosslinking co-polymerization reaction is studied by dielectric spectroscopy at various temperatures. A maximum in the dielectric constant was observed during the gelation reaction. At the same point, the dielectric loss switched from a linear decrease to a relatively constant behavior. Parallel experiments, performed with a magnetic stirrer, showed that this maximum is consistent with the gel-point. In the ethyl methacrylate homopolymerization reactions the dielectric constant did not go through a maximum but decreased monotonically. The evolution of the dielectric constant is found to depend on the extent of the reaction, but not on time and temperature separately.

Electrochemical oxidation mechanism of eugenol on graphene modified carbon paste electrode and its analytical application to pharmaceutical analysis

Electrochemical properties of eugenol were investigated on a graphene modified carbon paste electrode (CPE) by using voltammetric methods, which exhibited a well-defined irreversible peak at about 0.7V vs Ag/AgCl, NaCl (3M) in Britton-Robinson buffer at pH 2.0. Mechanism of the electrochemical reaction of eugenol was studied by performing density functional theory (DFT) computations and mass spectroscopic analysis. (CPCM:water)-wB97XD/aug-cc-PVTZ//(CPCM:water)-wB97XD/6-31G(d) level calculations predicted that the formation of product P2, possessing a para-quinoid structure, is preferred rather than the product P1, suggested in the literature, having an ortho-quinoid system. Determination of eugenol in a pharmaceutical sample was realized in the light of the electrochemical findings, and a validated voltammetric method for quantitative analysis of eugenol in a pharmaceutical formulation was proposed. The differential pulse voltammogram (DPV) peak currents were found to be linear in the concentration range of 1.0 × 10-7 to 1.7 × 10-5M. The limit of detection (LOD) and the limit of quantification (LOQ) were obtained to be 7.0 × 10-9 and 2.3 × 10-8, respectively.

Formation of composites between polyvinylimidazole and bentonites and their use for removal of remazol black B from water

ABSTRACT Poly(vinyl imidazole) (PVI)–clay (sodium bentonite and calcium bentonite) composites were designed and characterized for the removal of remazol black B (RB) that is an anionic dye water pollutant. The adsorption properties of PVI on bentonite clay particles were investigated and then PVI–clay composites were prepared at the optimum conditions for RB adsorption. X-ray diffraction (XRD) method was used for researching the intercalation behaviors of polymer–clay composites. Besides, Fourier-transform infrared spectroscopy and scanning electron microscopy analyses were carried out in order to identify the interaction mechanisms between PVI and bentonite in the composites.

Electrochemical characterization of luminol and its determination in real samples

The electrochemical behavior of luminol, an important molecule in forensic science, was studied in Britton–Robinson buffer solution (pH 2–pH 13) at a glassy carbon electrode using cyclic voltammetry and differential pulse voltammetry techniques. Luminol showed a well-defined and irreversible oxidation peak at 0.33 V (vs. Ag/AgCl) in 0.05 mol L−1 Britton–Robinson buffer solution at pH 12. The electrooxidation process of luminol was adsorption-controlled and irreversible over the pH range studied (2.0–13). The differential pulse voltammetric determination of luminol was carried out. Under optimal conditions, the glassy carbon electrode displayed a linear response over the range from 1.8 × 10−8 to 4.5 × 10−4 mol L−1 luminol concentration, and statistical data were evaluated. A commercially available real sample that contained luminol was analyzed according to this method. The luminol percentage of the sample was obtained as 21.2 (±0.4)%.

Determination of Mercury (II) Ion on Aryl Amide-Type Podand-Modified Glassy Carbon Electrode

A new voltammetric sensor based on an aryl amide type podand, 1,8-bis(o-amidophenoxy)-3,6-dioxaoctane, (AAP) modified glassy carbon electrode, was described for the determination of trace level of mercury (II) ion by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A well-defined anodic peak corresponding to the oxidation of mercury on proposed electrode was obtained at 0.2 V versus Ag/AgCl reference electrode. The effect of experimental parameters on differential voltammetric peak currents was investigated in acetate buffer solution of pH 7.0 containing 1 × 10−1 mol L−1 NaCl. Mercury (II) ion was preconcentrated at the modified electrode by forming complex with AAP under proper conditions and then reduced on the surface of the electrode. Interferences of Cu2

Elucidation of Mercury Ion Binding Property of a New Aryl Amide Type Podand by Electrochemical and Fluorescence Measurements

Abstract A new aryl amide type podand (AAP), 1,8-bis(o-amidophenoxy)-3,6-dioxaoctane, was synthesized and its mercury ion binding property was elucidated by electrochemical and fluorescence measurements. The effects of supporting electrolyte, pH and scan rate on the electroreduction of AAP and on cyclic voltommogram of mercury ion were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was observed that the complex formation between AAP and mercury ion exhibited pH-dependent behavior in different electrolyte solutions. Elucidation of such properties makes the AAP intriguing candidates as a modifying agent in sensor application for determination of mercury ion in mixture of aqueous solution.