Solid-phase luminescent catalyst immunoassay for human serum albumin with hemin as labeling catalyst

A solid-phase luminescent catalyst immunoassay is described for the determination of human serum albumin (HSA) in solution; hemin is used as a label which catalytically amplifies the sensitivity. The method is essentially a non-radioactive and non-enzymatic sandwich immunoassay. Anti-HSA antibody is covalently bound to a transparent plate, which then undergoes the immunochemical reaction with HSA in the test solution, and with the fixed amount of hemin-labeled anti-HSA antibody. After the two-step immunoreaction, the immunochemically-adsorbed hemin-antibody conjugate is quantified by means of the luminescence produced in a solution containing luminol and hydrogen peroxide. The luminescence intensity is correlated with the amount of HSA. The limit of detection for HSA is 1 ng ml^-1.     

Co2SnO4/Carbon Nanotubes Composites: A Novel Approach for Electrochemical Sensing of Hydrogen Peroxide

For the first time Co₂SnO₄ (CTO)/Carbon nanotubes (CNT) composites were prepared and used to modify glassy carbon electrodes for the amperometric determination of hydrogen peroxide. The catalytic activity of composites towards the oxidation of hydrogen peroxide was dependent on the quantity of CNT present in the composite and to the pH of the medium. The pure cobalt stannate phase with a ratio of 3 : 1 (CTO:CNT) exhibited the best catalytic activity towards hydrogen peroxide oxidation at low potentials (0.200 and 0.500 V). A linear relationship between current and hydrogen peroxide concentration was obtained with a sensitivity of 95 and 258 μA mM⁻¹ and a detection limit of 0.130 and 0.08 μM respectively.     

Electrocatalytic Oxidation of Hydrogen Peroxide on Poly(m‐toluidine)‐Nickel Modified Carbon Paste Electrode in Alkaline Medium

The poly(m‐toluidine) film was prepared by using the repeated potential cycling technique in an acidic solution at the surface of carbon paste electrode. Then transition metal ions of Ni(II) were incorporated to the polymer by immersion of the modified electrode in a 0.2 M NiSO₄, also the electrochemical characterization of this modified electrode exhibits stable redox behavior of the Ni(III)/Ni(II) couple. The electrocatalytic ability of Ni(II)/poly(m‐toluidine)/modified carbon paste electrode (Ni/PMT/MCPE) was demonstrated by electrocatalytic oxidation of hydrogen peroxide with cyclic voltammetry and chronoamperometry methods in the alkaline solution. The effects of scan rate and hydrogen peroxide concentration on the anodic peak height of hydrogen peroxide oxidation were also investigated. The catalytic oxidation peak current showed two linear ranges with different slopes dependent on the hydrogen peroxide concentration and the lower detection limit was 6.5 μM (S/N=3). The catalytic reaction rate constant, (k_h), was calculated 5.5×10² M^?1 s^?1 by the data of chronoamperometry. This modified electrode has many advantages such as simple preparation procedure, good reproducibility and high catalytic activity toward the hydrogen peroxide oxidation. This method was also applied as a simple method for routine control and can be employed directly without any pretreatment or separation for analysis cosmetics products.     

High Selective Determination of Anionic Surfactant Using Its Parallel Catalytic Hydrogen Wave

IntroductionAnionicsurfactants (AS)arewidelyusedinhouse holdorindustrialcleaners ,cosmetics ,researchlaborato ries,textiles ,pharmacies ,etc .,solargeamountofASreleasedintotheenvironmentarecausingpollution .There foreitisnecessarytodevelopafast,simpleandcosteffec tivemethodforthedeterminationofAS .Theofficialmeth odsrecommendedforthedeterminationofASarespec trophotometryandpotentialtitration .SpectrophotometricmethodanditsvariationsarebasedonthemeasurementofthecoloredassociatesofASwithposi…     

Kinetics of Iron-catalyzed decomposition of hydrogen peroxide in alkaline solution

The decomposition of alkaline hydrogen peroxide solutions at 20°C has been studied in the presence of both supported iron catalysts and in systems with iron initially in solution. Studies with an iron-alumina supported catalyst showed the decomposition reaction was first order with respect to total peroxide concentration, while studies with alkaline Fe³⁺ produced more complex behavior. This has been attributed to the presence of at least two distinct catalytically active iron species. The first species is highly active and gives rise to high initial rates of reaction. A decrease in concentration of this species is observed together with an increase in concentration of a second, less active, iron species. The catalytic behavior of this “aged” iron species was found to be very similar to that of the supported iron catalyst.     

Kinetic determination of traces of manganese(II) by its catalytic effect on the oxidation of acid blue 45 with hydrogen peroxide

A catalytic method is described for the determination of trace amounts of manganese(II) based on its catalytic effect on the hydrogen peroxide oxidation of an anthraquinone dye, Acid blue 45 (C.I. 63010). The reaction is followed spectrophotometrically by measuring the rate of change in absorbance of the dye at 595 nm. The calibration graph (rate constant (tg α) vs. manganese concentration) is linear in the range 4–25 ng Mn ml^?1, the relative standard deviation being 1.9% at the 13 ng Mn ml^?1 level. There are few interferences. The kinetic parameters of the reaction were investigated and the role of hydrogen peroxide and hydrogencarbonate ions is discussed.     

Sandwich-type amperometric immunosensor for human immunoglobulin G using antibody-adsorbed Au/SiO2 nanoparticles

A novel sandwich-type electrochemical immunosensor for human immunoglobulin G (hIgG) was developed using Au/SiO₂ nanoparticles (NPs) with adsorbed horseradish peroxidase-anti-hIgG as the secondary antibody layer. The signal readout is based on the amperometric response to the catalytic reduction of hydrogen peroxide at an AuNPs-polythionine modified glassy carbon electrode. Under optimized conditions, the linear range is from 0.1 to 200 ng·mL^?1, with a detection limit of 0.035 ng·mL^?1 (at an S/N of 3). The immunosensor exhibited a performance that is better than that based on Au/SiO₂NPs-excluded secondary antibody.     

Quantitative analysis of hydrogen peroxide by <Superscript>1</Superscript>H NMR spectroscopy

A technique utilizing ¹H NMR spectroscopy has been developed to measure the concentration of hydrogen peroxide from 10^–3 to 10 M. Hydrogen peroxide produces a peak at around 10–11 ppm, depending upon the interaction between solvent molecules and hydrogen peroxide molecules. The intensity of this peak can be monitored once every 30 s, enabling the measurement of changes in hydrogen peroxide concentration as a function of time. ¹H NMR has several advantages over other techniques: (1) applicability to a broad range of solvents, (2) ability to quantify hydrogen peroxide rapidly, and (3) ability to follow reactions forming and/or consuming hydrogen peroxide as a function of time. As an example, this analytical technique has been used to measure the concentration of hydrogen peroxide as a function of time in a study of hydrogen peroxide decomposition catalyzed by iron(III) tetrakispentafluorophenyl porphyrin.Electronic Supplementary Material Supplementary material is available for this article at     

Factorial design analysis of the catalytic activity of di‐imine copper(II) complexes in the decomposition of hydrogen peroxide

Factorial design analysis was applied to the study of the catalytic activity of di‐imine copper(II) complexes, in the decomposition of hydrogen peroxide. The studied complexes show a tridentate imine ligand (apip), derived from 2‐acetylpyridine and 2‐(2‐aminoethyl)pyridine, and a hydroxo or an imidazole group at the fourth coordination site of the copper ion. The factorial design models for both [Cu(apip)imH]²⁺ and [Cu(apip)OH]⁺ were similar. Increasing the peroxide concentration from 3.2 × 10^?3 to 8.1 × 10^?3 mol L^?1 resulted in increased oxygen formation. Increasing the pH from 7 to 11 also increased oxygen formation and had an effect about twice as large as the peroxide one. Both complexes also had an important interaction effect between peroxide concentration and pH. However, increasing the catalyst concentration led to a decrease in total oxygen formation. The obtained results were corroborated by further data, achieved by using the usual univariate method, and helped to elucidate equilibrium steps occurring in the studied systems. In very alkaline solutions, the studied [Cu(apip)imH]²⁺ complex can form the corresponding dinuclear species, [Cu₂(apip)₂im]³⁺. While the mononuclear complex proved to be an efficient catalyst in hydrogen peroxide decomposition, the corresponding dinuclear compound seemed to be able to coordinate with the dioxygen molecule, inhibiting its observed release. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 472–479, 2001     

Study On The Catalytic Reaction Of β-Cd-Hemin Using 2, 3, 4-Trichlorophenol As Substrate And Analytic Application

ABSTRACT|The catalytic activity of various mimetic enzymes instead of the peroxidase have been investigated by 4-aminoantipyrine (4-AAP) and 2, 3, 4-trichlorophenol (TCP) to form a dye utilizing hydrogen peroxide as hydrogen acceptor. The different Chlorophenolic derivatives, which act as a substrate in β-CD-hemin-H₂O₂-4-AAP catalytic reaction, have been systematically studied.|Meanwhile, the relationship of structure-effect for the β-CD-hemin as catalyst, and chlorphenols as substrate has been respectively discussed. The mechanism of catalytic reaction has been investigated. The results showed that β-CD-hemin was the best mimetic enzyme for peroxidase among those tested and TCP was a good substrate for the determination of hydrogen peroxide with β-CD-hemin. The method for the determination of hydrogen peroxide was proposed using 4-AAP-TCP system with β-CD-hemin as catalyst. A linear calibration graph was obtained over the H₂O₂ concentration of 4.8×10-^?8-7.7×10-^?5M, and the relative standard deviation at a H₂O₂ concentration of 2.8×10-^?5M was 2.5%. The apparent molar absorptivity of the chromogenic reaction for H₂O₂ was 1.54× 10⁴ L.mol-^?1.cm^?1. Satisfactory results were obtained in the determination of H₂O₂ in synthetic samples by this method.

Also, the method was coupled with the glucose oxidation reaction to determination glucose in human serum.     

Application ofo-Hydroxyphenylfluorone as a Fluorogenic Indicator to the Determination of Hydrogen Peroxide and Oxidase Substrates Based on the Catalytic Effect of Hemin

A highly sensitive fluorescence quenching method has been developed for selective determination of hydrogen peroxide based on the catalytic effect of hemin on theo-hydroxyphenylfluorone (a new fluorogenic substrate) and hydrogen peroxide system. Under optimum conditions, the calibration graph was linear over the range 0–1.0 × 10⁻⁶mol/liter hydrogen peroxide, with a limit of detection of 8.0 × 10⁻⁹mol/liter in a 10-min reaction period. It can easily be incorporated into the determination of biochemical substances that produce hydrogen peroxide under catalytic oxidation by their oxidase. This possibility has been tested for the determination of glucose in human sera as an example.     

Determination of thallium(III) with novel arsenoxylphenylazo rhodanine after pre-concentration and separation

A new catalytic kinetic fluorescent method for determination of trace thallium(III) was investigated. The method was based on the catalytic effect of thallium on oxidation of 3-p-chlorophenyl-5-(2′-arsenoxylphenylazo) rhodanine (4ClRAAP) by hydrogen peroxide in potassium hydrogen phthalate-hydrochloric acid (pH?=?5.2). Under the optimum conditions the great increase of fluorescence intensity had a linear relationship against the concentration of thallium in the range of 0.43 to 10.0?µg?L^?1 with a detection limit of 2.6?×?10^?10?g?L^?1. The coexistent metal ions can be separated, and thallium can be enriched by polyamide, which greatly improved the selectivity and sensitivity of the system. The method was applied to determine trace amount of thallium in wine, water and mineral samples, with satisfactory results.     

Study and Application on Polarographic Catalytic Wave of Human Serum Albumin in the Presence of Kio3

ABSTRACT

A polarographic catalytic wave of human serum albumin (HSA) in the presence of KIO³ was reported. In 0.1 M NaAc～HAc buffer (pH4.7) solution, a reduction wave of HSA with peak potential ?0.60 V (vs., Ag/AgCl) resulted from the reduction of five disulfide linkages to sulfhydryl group. In the presence of KIO³, HSA yielded a polarographic catalytic wave at the original potential due to reduction and regeneration of these disulfide linkages. The catalytic wave can be used to determine trace of HSA. In the 0.1 M HAc～NaAc (pH4.7±0.2) ～1×10^?3 M KIO³ solution, the peak current was linearly proportional to HSA concentration in the range of 1.5×10^?7～7.5×10^?7 M. The catalytic wave improved two orders of magnitude in sensitivity compared with corresponding reduction wave.     

Determination of hydrogen peroxide concentration in THOR coolant during reactor operation

The concentrations of hydrogen peroxide formed in the coolant due to radiolysis were studied during THOR operation at 1 MW. The relation between doses and hydrogen peroxide formation in a neutron-gamma mixed field was investigated. The initial concentration was 2.3×10^–5 g/ml at the beginning of reactor operation, and then it was increased rather rapidly at the first 9 h. The increasing rate was slowed down till the end of 30 h operation. The maximum concentration of hydrogen peroxide was found to be 4.7×10^–5 g/ml, and its decrease followed the exponential curve.     

FURTHER STUDIES ON THE KINETICS AND MECHANISM OF THE COPPER-IMIDAZOLE CATALYSED DECOMPOSITION OF HYDROGEN PEROXIDE

Abstract

The catalytic decomposition of hydrogen peroxide in the presence of the tetrakis(imidazole)copper(II) complex was investigated. The kinetics, based on the rates of oxygen evolution, indicated that a ternary copper(I1)-imidazole-peroxo complex is involved in the rate-determining step. The equilibrium constant for the coordination of hydrogen peroxide to the cupric ion, and the acid dissociation constant for the coordinated H202 ligand were calculated as 1.7 M¹ and 2.1 × 10⁹ M, respectively. The ternary complex undergoes intramolecular electron transfer, with k = 4 s¹, generating Cu(1) species which can react with hydrogen peroxide or dioxygen, returning to the catalytic cycle. A complete mechanism is proposed, based on the kinetics of oxygen and on the electrocatalytic behdviour observed for the copperimidazole complexes under a dioxygen atmosphere.     

Advanced oxidation processes for decolorization of aqueous solution containing acid red G azo dye

Some investigations concerning the decolorization of Acid Red G azo dye by photooxidation with hydrogen peroxide were performed. The influences of pH, oxidant concentration, and the presence of Fe²⁺ or other metal ions (Co²⁺, Cu²⁺, Ni²⁺, Mn²⁺) as potential catalysts, were investigated. The best results were obtained in the presence of ferrous ions in acid and neutral media. The other ions are not as effective as Fe²⁺ for dye decolorization. Co²⁺ and Cu²⁺ ions have a catalytic action, at low concentration, within a wide range of pH. Ni²⁺ and Mn²⁺ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid Ni²⁺ and Mn²⁺ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid pH values, but show a weak action in alkaline media.     

Bleacing of olive mill wastewater by clay in the presence of hydrogen peroxide

Treatment of olive mill wastewater (OMW) with clayey soils in the presence of hydrogen peroxide (H₂O₂) allows the elimination of phenolic compounds responsible for the black-brownish color of this industrial effluent. The aim of this research was to define optimal physicochemical parameters for the bleaching of OMW with clay in the presence of hydrogen peroxide. Two clayey soil powders were tested (A and B) and the results obtained indicate that high bleaching could be reached after 24 hours exposure of OMW to 7 % (W/V) clay material A in the presence of 0.5 % (V/V) hydrogen peroxide. Under these conditions, the bleaching led to about 87 % decrease of polyphenols (PF) and a 66 % decrease of the Chemical Oxygen Demand (COD). The structure of clay and its concentration in iron salts have an effective adsorbent and catalytic effect on the removal of the majority of polyphenols.     

Simple spectrophotometric method for the determination of sulfur dioxide by its decolorizing effect on the peroxovanadate complex

A simple, rapid, and economical spectrophotometric method is developed for the determination of sulfur dioxide in sugar and air samples. The developed method is based on a red-brown peroxovanadate complex (λ_max = 470 nm) produced in 2 M sulfuric acid when ammonium metavanadate is treated with hydrogen peroxide. Under fixed concentrations of hydrogen peroxide and ammonium metavanadate, when sodium metabisulfite (Na₂S₂O₅ = 2SO₂) is added, it preferentially reacts with hydrogen peroxide producing sulfuric acid, and the unreacted hydrogen peroxide then reacts with ammonium metavanadate; therefore, the concentration of sulfur dioxide is directly proportional to a decrease in the concentration of the peroxovanadate complex. The stoichiometric ratio between hydrogen peroxide and ammonium metavanadate as well as the stability constant of the complex are determined by the modified Job’s method and the respective values are found to be 1: 1 and 2.5 × 10⁴ mol⁻¹ L, respectively. The system obeys Lambert-Beer’s law in the concentration range 3.57–64.26 ppm of sulfur dioxide. The molar absorptivity, correlation coefficient, and Sandell’s sensitivity values are found to be 0.649 × 10³ L mol⁻¹ cm⁻¹, 0.9908, and 0.1972 μg cm⁻², respectively. The method is applied to the determination of sulfur dioxide present in commercial sugars and air samples. The results obtained are reproducible with a standard deviation of 0.02–0.05. For method validation, sulfur dioxide is also determined separately following the AOAC method for an air sample and the ICUMSA method for commercial sugars. The results obtained by the developed and official methods are in good agreement. The text was submitted by the authors in English.     

Localized surface plasmon resonance sensor for simultaneous kinetic determination of peroxyacetic acid and hydrogen peroxide

A new sensor for simultaneous determination of peroxyacetic acid and hydrogen peroxide using silver nanoparticles (Ag-NPs) as a chromogenic reagent is introduced. The silver nanoparticles have the catalytic ability for the decomposition of peroxyacetic acid and hydrogen peroxide; then the decomposition of them induces the degradation of silver nanoparticles. Hence, a remarkable change in the localized surface plasmon resonance absorbance strength could be observed. Spectra-kinetic approach and artificial neural network was applied for the simultaneous determination of peroxyacetic acid and hydrogen peroxide. Linear calibration graphs were obtained in the concentration range of (8.20 × 10⁻⁵ to 2.00 × 10⁻³ mol L⁻¹) for peroxyacetic acid and (2.00 × 10⁻⁵ to 4.80 × 10⁻³ mol L⁻¹) for hydrogen peroxide. The analytical performance of this sensor has been evaluated for the detection of simultaneous determination of peroxyacetic acid and hydrogen peroxide in real samples.     

Catalytic activity of iron-containing polymers in hydroxylation of benzene with hydrogen peroxide

Hydroxylation of benzene with hydrogen peroxide in aqueous acetonitrile at 50°C was studied. The KU-2-8 and KU-1 cation exchangers, and also specially synthesized cation exchangers and phenolformaldehyde resins derived from pyrocatechol and resorcinol, all modified with Fe(III) cations, were used as catalysts. The macrocomplex KU-2-8/Fe³⁺ showed the highest catalytic activity and ensured 32% yield of phenol in 15 min. The formation of phenol depends in a complex fashion on the initial concentration of hydrogen peroxide, content of Fe(III) ions in the polymer, and reaction time.