Showing papers on "Color reaction published in 2000"

Determination of some phenothiazine drugs based on colour reaction with potassium periodate

Abstract: A simple, rapid and sensitive method for the determination of six phenothiazine drugs, either in pure form or in pharmaceutical formulations, is described. The method is based on the formation of stable phenothiazine free radical by the use of potassium periodate as the chromogenic reagent in sulphuric acid medium. The reaction is suggested to proceed via oxidation of the phenothiazine nucleus into a semiquinonoid radical. The wavelengths of maximum absorption range from 500 to 525nm. Molar absorptivities range from

Analytical improvements in barlow reaction coupled to hplc detection of nicotine and its metabolites

Abstract: The aim of this work was to optimize the conditions of a Barlow reaction coupled with HPLC to assay nicotine and its metabolites cotinine, trans-hydroxycotinine, and pyridylcarbinol. Thiobarbituric acid was chosen as chromogen and the incubation time for the reaction was set at 15 minutes. The mobile phase was a mixture of acetate buffer 0.05 mol/L pH 5.2, acetonitrile, tetrahydrofuran, triethylamine (86.0/11.4/2.5/0.1 v/v), and acetic acid to pH 5.4. Applied to a population of 30 smokers, the method was shown to be simple, reliable, and rapid (under 20 minutes).

Spectrophotometric Quantitation of Fluoxetine Hydrochloride Using Benzoyl Peroxide and Potassium Iodide

Abstract: Fluoxetine hydrochloride reacts with benzoyl peroxide and potassium iodide, after heating for 1 min at 30 °C, to give a blue colour having maximum absorbance at 570 nm. The reaction is selective for fluoxetine with 0.01 mg/mL as visual limit of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer’s law from 0.1 mg/10 mL to 2.0 mg/10 mL of fluoxetine and the relative standard deviation is 0.68%. The qualitative assessment of tolerable amounts of other drugs is also studied.

A rapid estimation of urea in adulterated milk using dry reagent strip

Abstract: +his-articl describes development and optimization of a visually evalua Ie dry reagent strip technique for semiquantitative estimation of urea in adulterated milk. It is based on (i) urease reacting with urea to liberate ammonia and carbon dioxide and (ii ) liberated ammonia reacting with a specific chromogen to change color of the strip from light yellow to magenta, which is visible with naked eyes. The technique is versatile as (i) it is used single step-working reagent to complete the reaction within 30 s at room temperature, (i i) gives different shades of color from yellow to magenta, depending upon concentration of urea present in the milk, (iii) this strip can measure urea concentration as low as 0.1 giL and (iv) thi s dry reagent strip is stable up to one year at room tempera~ur~

Beet/sugarcane antioxidant composition

Abstract: PROBLEM TO BE SOLVED: To obtain an excellent antioxidant by forming a beet/sugarcane antioxidant composition which has specified physicochemical properties such as elemental analysis values, mol.wt., m.p., organic content, solubility in solvents, color reaction, discrimination among basicity, acidity and neutrality, color, shape, antioxidant properties and ultraviolet-absorbing capability. SOLUTION: This composition has such physicochemical properties that the elemental analysis values of C, H and N are 47.8%, 6.3% and 9.8%, respectively; the mol.wt. is 500-50,000; the m.p. is 300 deg.C or higher; it does not change even at 300 deg.C or higher; the organic content is 90-95%; it is completely soluble in water, easily soluble in an aqueous 50% ethanol solution, hardly soluble in an aqueous 75% ethanol solution and insoluble in ethanol; it has such color reactions that the ninhydrin reaction is + and the phenol-sulfuric acid reaction is +; its 1% aqueous solution is brown and clear; it has a pH of 5.0-6.5; it is a brown powder; and it exhibits strong antioxidant properties and ultraviolet absorption capability. This composition is prepared by removing low-mol.-wt. substances from a waste liquid separated in the chromatography step of a beet/cane sugar production plant.

Color Reaction of Aromatic Aldehyde with Serum Protein and Its Application to the Determination of Serum Total Globulin Concentration

Abstract: The reaction of four aromatic aldehydes including p-dimethylaminobenzaldehyde (p-DMABA) with serum protein has been studied. The aromatic aldehydes gradually reacted with serum globulin with the irradiation of a fluorescent lamp at room temperature to form a colored product with an absorption maximum at about 520 to 635 nm with high molar absorptivity, while only slightly reacting with serum albumin. The reaction rate increased as the intensity of light increased, and at about 3000 luxes the reaction completed within 45 min after the reaction started. Of the four aromatic aldehydes evaluated, the colored product of p-DMABA indicated the most excellent spectral characteristics. Based on these results, this aromatic aldehyde was applied to the detemination of the serum total globulin concentration. The measurement values by the proposed method, using a γ-globulin solution as a standard material, correlated well with those by the method of Goldenberg and Drewes using glyoxylic acid (r = 0.983), the combined biuret-BCG method (r = 0.949) and moderately with the combined biuret-cellulose acetate electrophoresis method (r = 0.899).

Sensitivity and selectivity of the reaction of vanadium(V) with 4-(2-Pyridylazo)resorcinol on a solid support containing anion-exchange groups and modified with 8-hydroxyquinoline or 8-hydroxyquinoline-5-sulfonic acid

Abstract: The effect of the modification of a solid support with 8-hydroxyquinoline (HQ) and 8-hydroxyquinoline-5-sulfonic acid (HQ-SFA) on analytical characteristics of the reaction of vanadium(V) with 4-(2-pyridylazo)resorcinol (PAR) on a solid phase was studied for polyacrylonitrile fiber filled with the AV-17 anion exchanger. Diffuse reflection spectra of the initial and modified supports and of vanadium(V) complexes of PAR on these supports were recorded. It was found that vanadium reacts with PAR on modified supports only in acid solutions. The conditions for the adsorption of vanadium and the dependences of the analytical signal on the acidity of the PAR solution and on the concentration of the modifier on the support were determined. The limits of vanadium detection by the reaction with PAR were calculated (0.5 and 1 ng/mL for AV-17-HQ and AV-17-HQ-SFA, respectively). The selectivity of the reaction of vanadium with PAR on modified supports was estimated with respect to copper, aluminum, iron(III), and zinc. It was found that the modification of the support with HQ and HQ-SFA impairs the analytical characteristics of the reaction of vanadium with PAR on the solid phase and that the use of modified supports for the color reaction of vanadium with PAR is inappropriat

Spectrophotometric Determination of Trace Thallium with Cadion 2B Using Polyurethane Foam as an Adsorption _ separating Material

Abstract: It was investigated that the color reaction of thallium with Cadion 2B in the NH3-NH4Cl medium at pH 11.5～12.5 with Triton X-100. Thallium(Ⅲ) and Cadion 2B form a 1∶4(molar ratio)red complex with apparent molar absorptivity 9.3×104 L·mol-1·cm-1 at 500 nm of detection wavelength. The coloration of the reaction is completed for an instant at room temperature and the color is stable at least for 12 h. Beer's law is obeyed in the mass concentration range of 0～800 μg/L for thallium. A method for the determination of trace amount of thallium by spectrophotometry was established using polyurethane foam as an adsorption _ separating material. The proposed method is rapid and accurate and has been applied to determine trace amounts of thallium in geological samples in aqueous solution with recoveries of 97.0%～106%. The relative standard deviations(n=5) are less than 4.1%. The results obtained are in good agreement with the values obtained by AAS.

Rapid test for formaldehyde determination

Abstract: The invention relates to a test kit for the rapid determination of formaldehyde in textile materials, which comprises; a sealed ampoule, filled with a defined volume of a reagent mixture, which produces a colour change on reaction with formaldehyde; a test-tube for mixing the reagent mixture and a defined volume of an extract from the textile material; and a reaction vessel, or a measuring cuvette for the mixture of extract and reagent mixture and subsequent carrying out of a colour reaction at elevated temperature.

Electrochemical enzyme immuno assay

Abstract: The invention relates to a method for carrying out an enzyme immuno assay (EIA, ELISA) with a sample. A reaction partner is added to the sample. An enzyme is coupled to the reaction partner. When a substrate is added, said enzyme triggers a redox reaction and a colour reaction of the substrate. Free reaction partners are removed and the substrate is subsequently added to the sample. Electrodes are introduced into the sample which is electrochemically measured.

Spectrophotometric Determination of Iron with 2-(2-Imidazolylazo)-5-diethylamino Phenol

Abstract: In this paper, the condition of color reaction of a new reagent 2-(2-imidazolylazo)-5-diethylamino phenol(IZAPN) with Fe 3+ is reported Results show that the IZAPN reacts with Fe 3+ to form a stable purple complex(1∶3) in the buffer solution of HAc-NaAc(pH5 0)The wavelength of absorption maximum and the apparent molar absorptivity are 590nm and 3 56×10 4L·mol -1 ·cm -1 , respectively Beer's law is obeyed in the range of 0-0 8mgFe 3+ /L The method has been applied to the direct determination of iron in pure aluminium and aluminium alloy with satisfactory results The recovery of standard addition is 100 3%-100 6% with precision of 1 6%-3 9% RSD(n=6)

Method for visualizing gas flow in soil

Abstract: PROBLEM TO BE SOLVED: To visualize a flow of a gas in soil by injecting the gas in the soil by adding a coloration reagent and color identifying it SOLUTION: As a coloration reagent, a reagent which is colorless in an initial state but brings about a color reaction when a specific gas is applied, a hydrogen ion concentration reagent which color identifies in an initial state but becomes another color or colorless by a specific gas or the like is used Soil 3 obtained by mixing cement suspension supernatant colored with red by a phenol phthalein of a coloration reagent with cement mixed fine sand is contained in a transparent acrylic column 1, a pressure reducing valve 8 is regulated, and a carbonic acid gas is sent from a gas cylinder 9 into the soil 3 while holding a flow rate of a flowmeter 6 constant After the gas is sent, the soil 3 is urged out from the column 1, sliced at about each 5 cm, and its section is observed Then, though the soil 3 before the gas is sent is red by the phenol phthalein, but after the gas is fed, a part brought into contact with the carbonic acid gas becomes colorless by a neutralization Accordingly, a flowing state of the gas is observed from its color erasing state

Sheet for detecting nitrogen dioxide

Abstract: PROBLEM TO BE SOLVED: To provide a sheet for detecting nitrogen dioxide by color reaction with stable sensitivity. SOLUTION: N-(1-naphthyl)ethylenediamine dichlorine acid salt, sulphonyl acid, paratoluenesulfone acid, alcohol humectant, preferably ethyleneglycol, are developed into a carrier sheet material, and an azoic dye is generated by nitrogen dioxide. Also, a fine-powder silica gel for accelerating reaction or alumina is preferably carried by the above sheet material.

Differentiating at least two different types of residues on hard surfaces comprises contacting body having adsorption materials containing chemical substances suitable for adsorbing residues with surface to be investigated

Abstract: A process for differentiating at least two different types of residues on hard surfaces is novel. Differentiating at least two different types of residues on hard surfaces comprises contacting a body having adsorption materials suitable for adsorbing residues with the surface to be investigated. The adsorption materials contain chemical substances which undergo a visual color reaction in the presence of different residues to allow a qualitative allocation to a determined type of residue, or adsorption materials are applied to the chemical substances which undergo a visual color reaction in the presence of different residues to allow a qualitative allocation to a determined type of residue.