Showing papers on "Color reaction published in 2012"
06 May 2012
TL;DR: A method for estimating ethanol in alcoholic-drinks by direct reaction is presented and the absorbance maxima for the ethanol was found to be 578 nm.
Abstract: A method for estimating ethanol in alcoholic-drinks by direct reaction is presented. The method consist of color reaction of ethanol with sodium dichromate. The colorimetric quantification was based on the formation of green colored chromate ions resulting from treatment of ethanol and sodium dichromate as limiting reactant in presence of sulfuric acid and acetate buffer pH 4.3. The absorbance maxima for the ethanol was found to be 578 nm. The influence of acetate buffer pH, reaction time, and Beer’law on color development and sensitivity were investigated and optimal assay conditions established. The limits of detection and quantification for ethanol were determined to be 0.6 mg/mL and 1.9 mg/mL.
52 citations
TL;DR: Three analytical procedures commonly used for determining flavonoid content in plant samples in terms of chromogenic relationships and the reaction products of different flavonoids structures are compared by means of using Flavonoid standards with flavone, flavonol, flavanone, Flavanol, and isoflavone and analytes such as phenolic acids commonly found in plant extracts.
Abstract: Flavonoids in plants have gained worldwide attention because of their benefits for human health. This study compared three analytical procedures commonly used for determining flavonoid content in plant samples in terms of chromogenic relationships and the reaction products of different flavonoid structures by means of using flavonoid standards with flavone, flavonol, flavanone, flavanol, and isoflavone and analytes such as phenolic acids commonly found in plant extracts. Procedure A produced a stable color reaction between 3-hydroxy-4-keto-flavonoids (flavonols) and 5-hydroxyflavones and was highly sensitive. Procedure B produced color reactions among most of the flavonoids, but the reaction products had different colors and faded over time. Procedure B also produced a color reaction with caffeic and chlorogenic acid. Procedure C was the most sensitive. It produced a color reaction and, like procedure A, could be used to quantify flavonols and 5-hydroxyflavones, but also showed color reaction toward caffeic and chlorogenic acid. On the basis of the results, the current three procedures are not satisfactory for determining all of the types of flavonoid. Two issues needed to be clarified before a promising determination of flavonoid content could be performed with chromogenic assays. The first is a survey of the literature to screen the possible predominant component of flavonoid in analytes. The other is guided by the predominant flavonoid; a promising calibration curve for flavonoid detection can be established on the basis of the selection of an appropriate method and a chemical standard with an equivalent dose response to the predominant flavonoid.
18 citations
TL;DR: In this paper, a simple selective and sensitive catalytic kinetic spectrophotometric method for the determination of trace amount of organophosphorus pesticides has been proposed, which is based on the catalytic effect of organic pesticides (malathion, dimethoate, and phorate) on the oxidation of leuco crystal violet by potassium iodate in hydrochloric acid medium to give a violet colored dye.
Abstract: A simple selective and sensitive catalytic kinetic spectrophotometric method for the determination of trace amount of organophosphorus pesticides has been proposed. The method is based on the catalytic effect of organophosphorus pesticides (malathion, dimethoate and phorate) on the oxidation of LCV (leuco crystal violet) by potassium iodate in hydrochloric acid medium to give a violet colored dye. The dye shows maximum absorption at 592 nm. The fixed-time method was used for 15 min. The system obeys Beer’s law in the range of 0.02-0.2, 0.032-0.32 and 0.03-0.3 µg mL-1, for malathion, dimethoate, and phorate, respectively. Important analytical parameters such as time, temperature, reagent concentration, acidity etc, have been optimized for complete color reaction. Sandell’s sensitivity and molar absorptivity for the system were found to be 0.0002, 0.0004, 0.0004 µg cm-2 and 1.2 × 106, 5.21 × 105, 6.3 × 105 L mol-1cm-1, respectively. The proposed method was satisfactorily applied to micro-level determination of organophosphorus pesticides in vegetable samples.
6 citations
Patent•
19 Sep 2012
TL;DR: In this article, a color reaction-based NO (Nitric Oxide) measuring method is characterized in that through the coordination between rear earth and salicylate, NO is partially oxidized to form a stable cobalt blue nitrogen trioxide in a boosting manner; and qualitative and quantitative analysis of NO are respectively performed according to the it's color features at 600-700 nm and its absorbance when peak wavelength is absorbed.
Abstract: A color reaction-based novel NO (Nitric Oxide) measuring method is characterized in that through the coordination between rear earth and salicylate, NO is partially oxidized to form a stable cobalt blue nitrogen trioxide in a boosting manner; and qualitative and quantitative analysis of NO are respectively performed according to the it's color features at 600-700 nm and its absorbance when peak wavelength is absorbed. The specific method is that butyl acetate and other organic solvents are adopted to absorb or extract the NO, and the mixture of perchloric acid rare earth and the salicylate is added in the solution, after a period of reaction time, whether the NO exists or not, as well as its concentration, can be judged through observing the color of the solution or through measuring the absorbance of the solution at 640 nm. The method provided by the invention is simple and practicable, and is suitable for NO measurement of gases or biological samples.
5 citations
Patent•
27 Jun 2012
TL;DR: In this article, a color reagent made from colorimetry nanometer material and used for high sensitively and high selectively detecting melamine and application of the colour reagent is presented.
Abstract: The invention provides a color reagent made from colorimetry nanometer material and used for high sensitively and high selectively detecting melamine and application of the color reagent. A main body of the color reagent is formed by a metal nanometer material which is in single or composite composition, and the obtained metal nanometer material can be used for carrying out a color reaction with a melamine solution under the condition that a corrosive reagent of the metal nanometer material exists. A water-soluble metal nanometer optical probe manufactured by the color reagent disclosed by the invention has a stronger plasma resonance absorption effect in a visible region, the optical probe which is used as the color reagent has a highly-sensitive selectivity response for the melamine, the lowest concentration which can be detected by a visual method can be 0.6nM, and the visual method is the method with the lowest detection limit in the colorimetry reported at present. Compared with the method for detecting the melamine with the metal nanometer material reported at present, the method provided by the invention has the advantages that: the nanometer material does not need to be specially modified, and thus the method is more simple and convenient. The method provided by the invention is hopeful to be used for the simple, convenient and efficient detection for the melamine in food comprising milk products in liquid state or solid state.
5 citations
Patent•
18 Jul 2012
TL;DR: In this paper, a measuring method of iron was proposed, which consisted of the following steps of: preparing multiple Fe standard solutions with different concentrations; respectively adding a first nitric acid solution and a first potassium thiocyanate solution into the multiple Fe-standard solutions so as to carry out a color reaction; preparing a solution to be tested by taking a ferric phosphate lithium sample, and adding the second nitric acids solution and the second potassium thianate solution, and carrying out color comparison on the solution to test after the color reaction, thus obtaining iron content in
Abstract: The invention discloses a measuring method of iron. The measuring method comprises the following steps of: preparing multiple Fe standard solutions with different concentrations; respectively adding a first nitric acid solution and a first potassium thiocyanate solution into the multiple Fe standard solutions so as to carry out a color reaction; preparing a solution to be tested by taking a ferric phosphate lithium sample, and adding the second nitric acid solution and the second potassium thiocyanate solution into the solution to be tested so as to carry out the color reaction; and carrying out color comparison on the solution to be tested after the color reaction and the Fe standard solutions after multiple color reactions, thus obtaining iron content in the solution to be tested according to a color comparison result. Compared with the ration measuring method in the prior art, the measuring method provided by the invention utilizes a semi-quantitative colorimetric method to measure the iron content in the solution to be tested, the measured result of the method is exact and reliable, the operation is simple, the application is broad, and the cost is lower.
4 citations
01 Jan 2012
TL;DR: Ferric chloride reacts with acetyl salicylic acid and acetaminophen to give violet color having maxima at 520nm and a blue color having minima at 560nm respectively as discussed by the authors.
Abstract: Ferric chloride reacts with acetyl salicylic acid and acetaminophen to give violet color having maxima at 520nm and a blue color having maxima at 560nm respectively. The reaction is selective for both the analgesics with 0.01mg/10ml as visual limit of quantitation and provides a basis for a new spectrophotometric determination. The color reaction obeys Beer’s Law from 0.01mg/10ml to 2.5mg/10ml and the relative standard deviation is 0.85 for acetyl salicylic acid and 0.78 for acetaminophen respectively. The quantitative assessment of tolerable amounts of other drugs not interfering is also studied.
3 citations
Journal Article•
TL;DR: The results showed that the best extraction conditions were as follows,10.0 mL of 6 mol/L hydrochloric acid,15mL of distilled water and 30 min extracting time in boiling water bath as discussed by the authors.
Abstract: The conditions of extraction of total sugar in garlic were optimized.The results show that the best extraction conditions were as follows,10.0 mL of 6 mol/L hydrochloric acid,15mL of distilled water and 30 min extracting time in boiling water bath.Taking glucose as reference substance,phenol-sulfuric acid reagent as chromogenic reagent,the optimum conditions for color reaction were studied by detecting wavelength,reagent dosage,time of color reaction and temperature of color reaction,etc.The results showed that the optimum conditions for color reaction were as follows,0.2 mL reference substance solution or sample solution was accurately drawn,then 2.0 mL of distilled water,1.0 mL of 5 % phenol solution was added in turn,and then 5.0 mL of concentrated sulfuric acid was dropped rapidly.The solution was shaked to homogeneity after being placed at room temperature 5 min.And then it was heated in water-bath for 15 min.Finally,it was cooled to room temperature.The absorbance was determine in the maximum absorption wavelength 490 nm.The linear range of the method is 5.05 μg/mL-40.4 μg/mL.RSD of standard solution and the the sample are 1.58 % and 1.08 %.The recovery of standard addition is 95.74 %-98.28 %.This method had been applied to the determination of total sugar content in nine different garlic originating from Yulin-rendong.It has been proved that the total sugar content of these garlisc is 170.0 mg/g-220.0 mg/g.
3 citations
Patent•
18 Jan 2012
TL;DR: In this article, a portable color reaction device which comprises a colorless transparent color reaction plate, wherein the reaction plate is subject to vacuum sealing in double aluminum foils, and the device also comprises a rubber plug (8).
Abstract: The utility model discloses a portable color reaction device which comprises a colorless transparent color reaction plate, wherein the color reaction plate comprises a color reaction plate carrier (1); a reaction tank array comprising a plurality of same reaction tanks (2) is arranged on the color reaction plate carrier (1); a non-transparent tank (3) and a blank tank (4) which are same as the reaction tanks (2) are arranged at one side of the reaction tank array; a reagent bin (5) is arranged at one side of each reaction tank (2); the reagent bins (5) are connected with the corresponding reaction tanks (2) through channels (10); the color reaction plate also comprises a color reaction plate cover plate (6); cover plate sample adding holes (7) are arranged at positions corresponding to the reagent bins (5) on the color reaction plate cover plate (6); color reagents are arranged in the reagent bins (5); aluminum foils are sealed on the surface of the cover plate sample adding holes (7); the color reaction plate is subject to vacuum seal in double aluminum foils; and the device also comprises a rubber plug (8). The device has the advantages of easiness in carrying, low cost, convenience for detection and high efficiency and is worthy of popularization and application.
2 citations
Journal Article•
TL;DR: In this paper, an indirect determination of formaldehyde in air samples is described based on colour reaction of Formaldehyde, p-amino benzene sulphonic acid and sulphur dioxide in hydrochloric acid medium.
Abstract: An indirect determination of formaldehyde in air samples is described. The method is based on colour reaction of formaldehyde, p-amino benzene sulphonic acid and sulphur dioxide in hydrochloric acid medium. The absorbance of pinkish-red coloured dye formed is measured at 510 nm. The colour system obeys Beer's law in the range of 1.8 to 9.6 μg of formaldehyde per 25 ml (0.072 – 0.38 ppm). Optimum conditions for colored development, and possible interferences, have been studied. The method is simple, sensitive and cost effective and have been used for the determination of formaldehyde in varies environmental samples.
2 citations
Patent•
11 Jul 2012
TL;DR: In this paper, a detection and pollution control method for nucleic acid amplification reaction product with no need for opening a reaction vessel is proposed. But the detection method requires the reaction vessel to be heated to the melting point of the microcrystalline waxes which are converted into a liquid state from a solid state and float on the upper layer of the reaction liquid.
Abstract: The invention provides a detection method for a nucleic acid amplification product, particularly a detection and pollution control method for the nucleic acid amplification reaction product with no need for opening a reaction vessel. The detection method includes steps that: before a nucleic acid amplification reaction, solid-state microcrystalline waxes wrapped with nucleic acid dye are added into the reaction vessel, and the microcrystalline waxes are guaranteed not to contact with reaction liquid; during the nucleic acid amplification reaction, the amplification reaction temperature is maintained to be lower than the melting point of the microcrystalline waxes, and the microcrystalline wax beads are guaranteed not to contact with the reaction liquid; after the nucleic acid amplification reaction, the reaction vessel is heated to the melting point of the microcrystalline waxes which are converted into a liquid state from a solid state and float on the upper layer of the nucleic acid reaction liquid; the wrapped dye enters the reaction liquid, is evenly mixed with the nucleic acid amplification reaction liquid, the nucleic acid amplification product is combined with the dye, and a color reaction is performed.
01 Jan 2012
TL;DR: A new spectrophotometric method which is fairly selective, non extractive, and quite accurate, precise, and sensitive is described here for the determination of lead based upon its colour reaction with 2,5- dimercapto-1, 3,4thiodiazole (DMTD).
Abstract: Summary: A new spectrophotometric method which is fairly selective, non extractive, is described here for the determination of lead based upon its colour reaction with 2,5- dimercapto-1, 3,4thiodiazole (DMTD). According to this lead (II) can be determined within the range from 1.0 to 50 µg per mL in a slightly acidic media (0.005 M HCl), to give a greenish yellow chelate complex, which has an absorption at 375 nm. The reaction proceeds fastly and color remains stable. While no special conditions are followed. The method is recommended for its routine use and is quite accurate, precise, and sensitive. Effect of Foreign ions is also studied at 40 µg/mL of lead.
TL;DR: In this paper, the authors determined cadmium by summable spectrophotometry of positive-negative peaks with cadion and Triton X-114 after cloud point preconcentration.
Abstract: Cadmium has been determined by summable spectrophotometry of positive-negative peaks with cadion and Triton X-114 after cloud point preconcentration. Influence factors on cloud point extraction, color reaction and absorbance were investigated by studying the summation absorbance of color compounds at 480 nm and 570 nm. The sensitivity and absorbance of this method are at least five times higher when compared with that of usual cadion spectrophotometry due to the summation of positive and negative peak. The proposed method is sensitive, simple, accurate and environmentally-friendly in the determination of cadmium in environment water.
TL;DR: In this paper, the synthesis of a triazene reagent 1-(4-antipyrine)-3-( 3-nitroaniline)-triazene (ANTA) and its color reaction with Hg (Ⅱ) was studied and a new spectrophotometric method for the determination of Hg(Ⅰ) was established.
Abstract: The synthesis of a new triazene reagent 1-(4-antipyrine)-3-( 3-nitroaniline)-triazene (ANTA) and its color reaction with Hg (Ⅱ) was studied and a new spectrophotometric method for the determination of Hg (Ⅱ) was established. The results showed that in the presence of micromulsion Tween-80, ASTA could reacted with Hg ( Ⅱ) to form a red stable complex of which the molar ratio of reagent︰metal was 2︰1 in Na2B4O7-NaOH medium.. The maximum absorption peak of the complex was located at 495 nm with the apparent molar absorption of 3.8 ×105 L·mol-1·cm-1. Beer′s law was obeyed in the range of 0.32～10 μg/10 mL for Hg ( Ⅱ) and the detection limit was 0.10 mg/L. Many ions did not interfere the colour reaction system due to the existence of ammonia. This method was applied to determination of Hg (Ⅱ) in lead-zinc ore samples, and the results were in accordance with those obtained by AAS method. Recovery was in the range of 103.0～103.2 % and the RSD(n=6) was not more than 4.6%.