Showing papers on "Color reaction published in 1993"
Patent•
13 Aug 1993TL;DR: In this paper, a sample from a suspect source is subjected serially to the indicated reagents in the liquid phase, the reagents after the first being applied only if no color reaction has been obtained in the preceding test.
Abstract: In a color reaction method for detecting particular classes of explosives, a sample from a suspect source is subjected serially to the indicated reagents in the liquid phase, the reagents after the first being applied only if no color reaction has been obtained in the preceding test. The second and third reagents only are applied in presence of the preceding reagent(s). The first reagent is an alkaline solution of a diazotizable aminoaromatic azo-dye precursor, which detects nitroaromatic explosives. The second reagent is a strongly acidic reagent containing a nitrate to nitrite ion reducing agent and a diazo-coupler, which detects organic nitrates and nitramines. The third reagent is zinc powder suspended in a liquid, which detects inorganic nitrates. The fourth reagent is an aniline salt in a homogeneous strongly acidic solution including a water-miscible organic solvent, which detects chlorates and bromates. The invention includes also a test kit for use in the method.
40 citations
TL;DR: Two sensitive methods for the determination of phenothiazine derivatives based on the formation of coloured salts of these drugs formed with Brilliant Blue or Orange-II in the presence of 0.1 M HCl are described.
30 citations
TL;DR: A flow injection method for the determination of formaldehyde was developed in this paper, based on its reaction with 3-methyl-2-benzthiazolinone hydrazone (MBTH) to yield a blue formazan anion.
Abstract: A flow injection method for the determination of formaldehyde was developed. It is based on its reaction with 3-methyl-2-benzthiazolinone hydrazone (MBTH) to yield a blue formazan anion. Typically 180 μl samples are injected into a buffered carrier stream with a frequency of 30 per hour. This sample line merges with the reagent stream containing MBTH, whereupon an azine is formed. After merging with a second stream containing an acidic solution of FeCl3 as reagent, MBTH is oxidized to an intermediate that attacks the azine yielding the formazan dye with an ɛmax at 635 nm. The method was applied to formaldehyde concentrations in the range from 0.15 mg/l to 15 mg/l. The relative standard deviation was 2.3% for 3 mg/l formaldehyde, and 5.1% for 0.3 mg/l, respectively. Strong reducing agents like nitrite interfere seriously. Out of the family of carbonyl compounds only acetaldehyde and propionaldehyde cause strong positive interference.
6 citations
TL;DR: In this paper, a simple, rapid, and sensitive kinetic method has been developed for the determination of traces of sulfite (0.05-2.5 μg/ml) based on the addition reaction of sulfites with methyl green at pH 8 and 25°C.
6 citations
Journal Article•
5 citations
TL;DR: In this paper, a method for indirect spectrophotometric determination of H2O2 is based on its oxidation with chlorine in basic medium and measurement of the unreacted Cl2 by the colour reaction with o-tolidine at 438 nm.
Abstract: A method for the indirect spectrophotometric determination of H2O2 is based on its oxidation with chlorine in basic medium and measurement of the unreacted Cl2 by the colour reaction with o-tolidine at 438 nm. The effective molar absorptivity for H2O2 with o-tolidine is 5.37×104 mol−1 cm−1 at pH 1.7. The lower limit of determination is 1.85×10−7 mol/l or 6.29 ppb. Br−, I−, NO−2, Pb2+ and Sn2+ interfere even in small amounts, but are not present in commercial H2O2.
5 citations
TL;DR: Using the results of quantum-chemical calculations (MNDO, PPP) the basic chromophoric system was identified as two coupled five-membered rings which have partial anti-aromatic character like the antiaromatic cyclopentadienyl cation as discussed by the authors.
Abstract: The long-wavelength absorption of the dye formed at the ninhydrin-amino acid color reaction is caused by the anion (enolate) of diketohydrindamine-diketohydrindylidene (Ruhemann's purple). Using the results of quantum-chemical calculations (MNDO, PPP) the basic chromophoric system was identified as two coupled five-membered rings which have partial anti-aromatic character like the antiaromatic cyclopentadienyl cation
5 citations
Patent•
09 Mar 1993
TL;DR: In this article, a new bioactive substance derived from propolis and represented by the formula was obtained by extracting propolis with ethyl alcohol, etc., and subsequently isolating and purifying the resultant extract by the conventional method, e.g high-performance liquid chromatography method.
Abstract: PURPOSE:To provide the subject substance showing an excellent anti-neoplasitc effect. CONSTITUTION:A new bioactive substance derived from propolis and represented by the formula. This compound can be obtained by extracting propolis with ethyl alcohol, etc., and subsequently isolating and purifying the resultant extract by the conventional method, e.g high-performance liquid chromatography method. Behavior of the above-mentioned compound during the purification process can be followed by ultraviolet absorption spectra: lambdamax: 212nm (epsilon=4600) and 288nm (epsilon=2600) (in methanol). In addition, the above-mentioned compound is soluble in methanol, ethyl acetate, chloroform and DMSO and sparingly soluble in an acidic water. Color reaction is positive in iodine reagent, BCG reagent and cerium sulfate reagent and the appearance is colorless solid.
3 citations
Patent•
16 Apr 1993
TL;DR: In this article, a new compound capable of exhibiting remarkable enzyme- inhibiting activity against casein kinase II and useful as an antitumor agent was obtained by inoculating a microorganism belonging to the genus Pseudorobillarda sp. F26668 into a nutrient source-containing medium and culturing the micro-organism under aerobic conditions.
Abstract: PURPOSE: To obtain a new compound capable of exhibiting remarkable enzyme- inhibiting activity against casein kinase II and useful as an antitumor agent. CONSTITUTION: A compound of the formula or its salt. This compound is obtained by inoculating a microorganism belonging to the genus Pseudorobillarda sp. or its variant (FERM P-13325), e.g. Pseudobillarda sp. F26668 into a nutrient source-containing medium and culturing the microorganism under aerobic conditions, harvesting the cultured mixture from the bacterial cell by normal separation means and separating and purifying the cultured product. Properties of the compound of the formula: Appearance, pale yellow solid; molecular formula, C 13 H 10 O 5 ; solubility, readily soluble in acetone, methanol and ethyl acetate and sparingly soluble in chloroform and water and insoluble in hexane; discrimination of acidic, neutral or basic substance, acidic substance; Rf value, 0.43 (using 'Kiesel gel 60F 254 (R)' manufactured by Merck & Co., Inc. and developed using chloroform/methanol); color reaction, positive to iodine reaction and molybdophosphoric acid reaction and negative to ninhydrin reaction. COPYRIGHT: (C)1994,JPO
2 citations
TL;DR: In this article, a new water soluble chromogenic reagent, 2-(5-bromo-pyridylazo)-5-[(N,N-dicarboxylmethyl)amino]-phenol has been synthesized.
Abstract: A new water soluble chromogenic reagent, 2-(5-bromo-pyridylazo)-5-[(N,N-dicarboxylmethyl)amino]-phenol has been synthesized. Its colour reaction with various metal ions was tested, and the acid dissociation constant of the reagent, and the stability constants of the chelates of Ni2+, Co2+, Cu2+, Mn2+, Pb2+, Zn2+ and UO
2
2+
were determined. The application of the reagent to spectrophotometric determination of nickel in irons is presented.
2 citations
TL;DR: In this article, color development based on the ion association of molybdophosphate with a cationic dye, a chloro derivative of Malachite Green (Cl-MG), was investigated in an aqueous acidic solution.
Abstract: Color development based on the ion association of molybdophosphate with a cationic dye, a chloro derivative of Malachite Green (Cl-MG), was investigated in an aqueous acidic solution. Cl-MG is very stable as its quinoid form in an acidic medium, and can easily react with molybdophosphate to form a green ion associate, which shows maximum absorption at 685nm. The experimental conditions for optimum color development have been examined. This color development reaction could be applied to the determination of trace amounts of orthophosphate. The molar absorptivity was 1.3×105dm3 mol-1cm-1 at 685nm.
TL;DR: It is found that this reagent can be used to identify Ag(+) and Hg(2+) and both of their sensitivities and selectivities are the best in all methods for the time being.
TL;DR: In this paper, the colour reaction of selenium with iodide and rhodamine B (RhB) has been studied and used to determine Selenium in some biological or chemical applications.
Abstract: We have studied the colour reaction of selenium (Ⅳ) with iodide and rhodamine B (RhB) which has been used to determine selenium. Although it is one of the highest sensitive colour reactions for determining selenium(Ⅳ), its sensitivity is still not high enough for the determination of trace amounts of selenium in some biological or
Patent•
02 Feb 1993
TL;DR: A physiologically active substance TAN-1515 having the following properties: Appearance, colorless crystal; melting point, 102-104 deg.C; molecular formula, C32H46O7; elementary analysis, C 70.82 H 8.54 (calculated value) and C 69.99H 8.91 (measured value); color reaction, positive to Barton reaction, iodine reaction, etc., and negative to ninhydrin reaction and Dragendorff reaction.
Abstract: PURPOSE:To obtain the new title substance useful as antiphlogistics because of phospholipase A2 inhibiting activity and useful as a synthetic intermediate for new derivative. CONSTITUTION:A physiologically active substance TAN-1515 having the following properties: Appearance, colorless crystal; melting point, 102-104 deg.C; molecular formula, C32H46O7; elementary analysis, C 70.82 H 8.54 (calculated value), C 70.99 H 8.91 (measured value); color reaction, positive to Barton reaction, iodine reaction, etc., and negative to ninhydrin reaction and Dragendorff reaction; classification of acidic, neutral or basic, acidic. The compound 12 is obtained by culturing a microorganism [e.g. Acremonium sp. FL-175559 strain (FERM BP-3487)] belonging to Acremonium and capable of producing a compound expressed by the formula and purifying the cultured mixture. Furthermore, temperature in the meddle period of culture is 20-30 deg.C and initial pH is preferably 6-8.
TL;DR: An assay method for determining organic hydroperoxides based on indamine dye formation using a water-soluble iron-(III) porphyrin as catalyst was developed, suggesting a general acid-base catalyzed reaction involving a heterolytic cleavage of the O-O bond.
Abstract: An assay method for determining organic hydroperoxides based on indamine dye formation using a water-soluble iron-(III) porphyrin as catalyst was developed. The assay was performed at pH 4.4 under anaerobic conditions and was applicable to flow-injection analysis. t-Butyl hydroperoxide was determined over the range of 1 to 40 nmol with r=0.999 and SD(%)=2.4 (n=5 at 4.8nmol). The mechanism of the catalytic reaction is discussed based on kinetic measurements, suggesting a general acid-base catalyzed reaction involving a heterolytic cleavage of the O-O bond.