This study investigates the electrocatalytic oxidation of glucose and some other carbohydrates on nickel/poly(o‐aminophenol) modified carbon paste electrode as an enzyme free electrode in alkaline solution. Poly(o‐aminophenol) was prepared by electropolymerization using a carbon paste electrode bulk modified with o‐aminophenol and continuous cyclic voltammetry in HClO4 solution. Then Ni(II) ions were incorporated to electrode by immersion of the polymeric modified electrode having amine group in 1 M Ni(II) ion solution. Cyclic voltammetric and chronoamperometric experiments were used for the electrochemical study of this modified electrode; a good redox behavior of Ni(OH)2/NiOOH couple at the surface of electrode can be observed, the capability of this modified electrode for catalytic oxidation of glucose and other carbohydrates was demonstrated. The amount of α and surface coverage (Γ*) of the redox species and catalytic chemical reaction rate constant (k) for each carbohydrate were calculated. Also, the electrocatalytic oxidation peak currents of all tested carbohydrates exhibit a good linear dependence on concentration and their quantification can be done easily. 相似文献
Summary We present some results on countable homogeneous 3-hypergraphs. In particular, we show that there is no unexpected homogeneous 3-hypergraph determined by a single constraint.The authors are grateful for support from NSERC (Canada) Grant A3040 相似文献
Determination of flavonoid markers quercetin, hesperetin, and chrysin, found in north Iranian citrus honey samples, was carried out by solid phase extraction (SPE) and isocratic liquid chromatographic separation using central composite design. Optimum conditions for SPE were achieved using 10 mL methanol/water (13:87, v/v, pH = 7) as the washing solvent and 4 mL methanol for elution. Good clean-up and high recovery >90% were observed for all analytes. The use of water/ACN/THF/AcOH (54:36:5:5, v/v) was found to serve as the optimum mobile phase composition and allowed for the separation of analytes from endogenous compounds present in honey. SPE parameters, such as maximum loading capacity and breakthrough volume, were also determined for each analyte. Limit of detection, linear range, recovery, repeatability of retention times, and peak heights were 3.11 × 10−8–4.44 × 10−8 g g−1, 0.50–50.0 μg mL−1 (R2 > 0.99), 90.7–96.9%, 3.0–3.6%, and 1.0–2.6%, respectively. Precision of the overall analytical procedure, estimated by five replicate measurements for quercetin, hesperetin and chrysin in citrus honey, as well as the relative standard deviations were 4.3%, 3.8%, and 5.5%, respectively.
Summary. A rapid and simple method for the preparation of 4-substituted 1-ethoxycarbonyl semicarbazide is reported. The reaction is
carried out under microwave irradiation by the reaction of five different isocyanates with ethyl carbazate.
Corresponding author. E-mail: mallak@cc.iut.ac.ir
Previous name. Shadpour E. Mallakpour
Received October 28, 2002; accepted October 31, 2002
Published online May 15, 2003 相似文献
Functionalized crosslinked polystyrene-co-divinylbenzene-co-chloromethylstyrene magnetic latex particles were prepared via emulsifier-free miniemulsion polymerization using 2, 2′ azobis (2-amidinopropane) dihydrochloride (V-50) as an initiator and in the presence of magnetite nanoparticles in the monomers. Transmission electron microscopy (TEM) proved the presence of magnetite nanoparticles in polymer particles. Differential scanning calorimetery (DSC) analysis of the product showed an exothermic signal due to crosslinking of chains through electrophilic aromatic substitution of phenyl groups with chloromethyl groups in the presence of the dispersed Fe3O4 as Lewis acid. This was proven by thermogravimetric analysis (TGA) via the loss of gaseous HCl. The results were also compared with those of magnetite-free miniemulsion polymerization using V-50. 相似文献
A novel chemiluminogenic reagent, refered to as spiro form fluorescein hydrazide, was synthesized, and its application to chemiluminescence (CL) determination of Co2+ is described. The method is based on the catalytic effect of Co2+ on the autoxidation of sulfite in basic solution to generate a series of powerful oxidative intermediates, which then oxidize colorless, nonfluoresent fluorescein hydrazide to generate strong CL emission. The CL signal is linearly related to the concentration of Co2+ in the range of 0.1–200nM with a detection limit of 0.04nM. The optimal conditions for the detection of Co2+ were evaluated, and the possible CL mechanism is discussed. The proposed method has been applied to the determination of Co2+ in pharmaceutical preparations and in soil samples. 相似文献
A capillary electrophoretic approach has been evaluated for the identification of seven currently recognised species of Eimeria infecting chickens. The second internal transcribed spacer of ribosomal DNA is PCR-amplified from any of the seven species using a single set of oligonucleotide primers (one of which is fluorescently labelled). The amplicons are heat-denatured and subjected to capillary electrophoresis in a MegaBACE 1000 (Amersham). The chromatograms captured are stored electronically and then analysed using MegaBACE Fragment Profiler software. Using control DNA samples representing monospecific lines of Eimeria, specific peaks in the chromatograms were defined for the unequivocal identification of each of the seven species and their differentiation. Electrophoretic reading and analysis are carried out automatically, thus making it a time- and cost-effective method. This procedure should find applicability as a tool for the quality control of Eimeria vaccines, the monitoring of coccidiosis outbreaks and the high-throughput analysis of oocyst samples for epidemiological surveys. 相似文献
We present experimental measurements of the polarization dependence of two-photon absorption in silicon photodiodes at 1550 nm, and we offer a simple theory that explains our observations. Based on this theory, we propose and demonstrate that it is possible to construct an optical cross-correlation system that is polarization insensitive, provided that one of the two input polarization states can be controlled. 相似文献