Rapid determination of ascorbic acid, dehydroascorbic acid, and total vitamin C by electrochemiluminescence with a thin-layer electrochemical cell

The original publication available at www.springerlink.comArticleANALYTICAL AND BIOANALYTICAL CHEMISTRY. 393(39971):1669-1675 (2009)journal articl

Quantum Communication Through a Spin-Ring with Twisted Boundary Conditions

We investigate quantum communication between the sites of a spin-ring with twisted boundary conditions. Such boundary conditions can be achieved by a flux through the ring. We find that a non-zero twist can improve communication through finite odd numbered rings and enable high fidelity multi-party quantum communication through spin rings (working near perfectly for rings of 5 and 7 spins). We show that in certain cases, the twist results in the complete blockage of quantum information flow to a certain site of the ring. This effect can be exploited to interface and entangle a flux qubit and a spin qubit without embedding the latter in a magnetic field.Comment: four pages two figure

Study on the Indirect Electrochemical Detection of Ammonium Ion with In Situ Electrogenerated Hypobromous Acid

This is the pre-peer reviewed version of the following article:ELECTROANALYSIS. 20(20):2205-2211 (2008), which has been published in final form at doi:10.1002/elan.200804311ArticleELECTROANALYSIS. 20(20):2205-2211 (2008)journal articl

Photochemical Reactions of Ge-Related Centers in Germanosilicate Glass Preparted by Sol-Gel Process (SOLID STATE CHEMISTRY-Amorphous Materials)

Germanosilicate glasses are prepared by a sol-gel method and the UV-photosensitivity of glasses is investigated by optical absorption, ESR, and photoluminescence measurements. Large changes in optical absorption are observed for the sol-gel-derived glass by the ultraviolet laser irradiation; a decrease in 5-eV band and increases in absorption around 4.5 and > 5.7 eV. Photoluminescence intensity under 248- nm excitation decreases with an increase in laser fluence and also with decrease in the 5-eV band. This result strongly implies the novel photochemical reaction from Ge2+ to Ge E' induced by excimer laser irradiation

Enzymatic flow injection method for rapid determination of choline in urine with electrochemiluminescence detection

In order to determine trace choline in human urine, a flow injection analysis (FIA) system has been developed by coupling an enzyme reactor with an electrochemiluminescence (ECL) detector. The enzyme reactor is prepared by covalently immobilizing choline oxidase (ChOx) onto the aminopropyl-controlled pore glass beads, which are then carefully packed into a micro column. The enzyme reactor catalyzes the production of hydrogen peroxide that is in direct proportion to the concentration of choline. In this study, the enzymatically produced hydrogen peroxide was detected by an ECL detector positioned at the down stream of an enzyme react:or based on the luminol/H2O2 ECL system. Under the optimized condition, the enzymatic FIA/ECL provided high sensitivity for the determination of choline with the detection limit as low as 0.05 mu M (absolute detection limit was at sub pmol level). The method was successfully applied in the determination of choline in the samples of human urine, and the analytical results were in good agreement with those obtained by using the microbore HPLC with an immobilized enzyme reactor-electrochemical detection system.ArticleBioelectrochemistry. 79(1):147-151 (2010)journal articl

Characterization of electrochemiluminescence of tris(2,2′-bipyridine)ruthenium(II) with glyphosate as coreactant in aqueous solution

Glyphosate, a phosphorus-containing amino acid type herbicide was used as a coreactant for studying of electrochemiluminescence (ECL) reaction of tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] in an aqueous solution. In a phosphate buffer solution of pH 8, glyphosate itself was known to be electrochemically inactive at glassy carbon electrode, however, it participated in a homogeneous chemical reaction with the electrogenerated Ru(bpy)(3)(3+), and resulted in producing Ru(bpy)(3)(2+) species at the electrode surface. Kinetic and mechanistic information for the catalysis of glyphosate oxidation were evaluated by the steady-state voltammetric measurement with an ultramicroelectrode. The simulated cyclic voltammogram based on this mechanism was in good agreement with that obtained experimentally. ECL reaction of Ru(bpy)(3)(2+)/glyphosate system was found to be strongly dependent on the media pH. In a pH region of 5-9, an ECL wave appeared at ca. +1.1 V vs. Ag/AgCl, which was caused by the generation of *Ru(bpy)(3)(2+) via a Ru(bpy)(3)(3+)-mediated oxidation of glyphosate. When pH >10, a second ECL wave was observed at ca. +1.35 V vs. Ag/AgCl, which was believed to be associated with a reaction between Ru(bpy)(3)(3+) and the species from direct oxidation of GLYP at a GC electrode surface.ArticleElectrochimica Acta 55(20):5532-5537 (2010)journal articl