Showing papers on "Color reaction published in 2014"

Acid-base titrations using microfluidic paper-based analytical devices

Abstract: Rapid and simple acid–base titration was accomplished using a novel microfluidic paper-based analytical device (μPAD). The μPAD was fabricated by wax printing and consisted of ten reservoirs for reaction and detection. The reaction reservoirs contained various amounts of a primary standard substance, potassium hydrogen phthalate (KHPth), whereas a constant amount of phenolphthalein was added to all the detection reservoirs. A sample solution containing NaOH was dropped onto the center of the μPAD and was allowed to spread to the reaction reservoirs where the KHPth neutralized it. When the amount of NaOH exceeded that of the KHPth in the reaction reservoirs, unneutralized hydroxide ion penetrated the detection reservoirs, resulting in a color reaction from the phenolphthalein. Therefore, the number of the detection reservoirs with no color change determined the concentration of the NaOH in the sample solution. The titration was completed within 1 min by visually determining the end point, which required ne...

Analysis of Cu(I) Complexes in Copper Sulfate Electroplating Solution by Using Reaction Kinetics with a Chelate Reagent

Abstract: Analysis of Cu(I) in copper sulfate electroplating solutions was conducted by absorption of a chelate of Cu(I) with bathocuproinedisulfonic acid, disodium salt (BCS). The absorbance of the color reaction of Cu(I) increased quickly in a few minutes after mixing with the chelate reagent and subsequently continued to increase slowly. To analyze the reaction kinetics of the color reaction, we divided Cu(I) complexes into two groups, small complexes and large Cu(I)-PEG complexes, and assumed the reaction of each group of complexes and BCS is a first order reaction with a specific reaction rate constant. We simulated the absorption curve with a good correlation and obtained the concentrations and the time constants, inverse of rate constants, of small complexes and large Cu(I)-PEG complexes. These concentrations and time constants are important parameters to control plating solutions. The time constant of small complexes can be attributed to the variation of the proportions of these small complexes. The smaller time constant of Cu(I)-PEG complexes can be considered the larger size distribution of Cu(I)-PEG with different chain lengths. Using this analysis, we monitored the variation of Cu(I) concentration in production lines for one month and found the increase of small complexes during the resting state of the lines. This increase corresponded to the tendency of occurring of brightening troubles.

Reaction device and method for visual detection of isothermal amplification of nucleic acid

Abstract: The invention discloses a method and a reaction device for visual detection of isothermal amplification of nucleic acid. The method comprises the following steps: in a special hermetic reaction device, adding a reagent capable of decomposing pyrophosphoric acid into phosphoric acid into a nucleic acid amplified reaction liquid in advance; after reaction, under the condition of not uncapping, mixing the nucleic acid amplified reaction liquid with other selected color reagents which are additionally stored in the device in advance to react and observing the color of the mixture after further reaction; and judging whether nucleic acid amplified reaction is carried out on a sample or not, wherein the selected color reagents are reagent combination capable of being in color reaction with phosphoric acid (radicals). The method disclosed by the invention is simple to operate and is quick and sensitive. The test result can be detected by virtue of naked eyes. The method is low in cost and makes up the defects in the existing technology for detecting nucleic acid amplification.

Dab-containing substrate kit for dyeing use which is produced using labelling enzyme

Abstract: Provided is a DAB-containing substrate kit which can increase specific dyeing intensity and can also prevent the precipitation of DAB in a DAB-containing substrate solution, which is caused by the aggregation of DAB, or the occurrence of non-specific dyeing, such as background dyeing, in a color reaction using a peroxidase-labeled antibody, wherein a color reaction solution containing DAB and imidazole that can act as a sensitizer for DAB is used. The kit according to the present invention comprises (A) a chromophore-containing solution which contains DAB that can act as a peroxidase chromophore and water and (B) a color-developing reagent which comprises at least one chelating agent selected from EDTA·2Na, EDTA·2NH 4 , GEDTA and NTA, a POE alkyl ether-type nonionic surfactant and/or a POP alkyl ether-type nonionic surfactant, imidazole, hydrogen peroxide and water, and the kit is composed of two or more packs in which at least the chromophore-containing solution (A) and the color-developing reagent (B) are stored separately.

Spectrophotometric Determination of Formaldehyde in Water Sample with Amino Acid-Acetylacetone

Abstract: Conditions for the color reaction of formaldehyde with acetylacetone by using amino acids instead of aq.ammonia or ammonium acetate as the donor of-NH2group were tested and a spectrophotometric method for determination of formaldehyde in water sample with glycine and acetylacetone as reagents was proposed.The optimized conditions found were as follows:① amount of 0.12 mol·L-1 glycine derivatizing agent:2 mL;② temperature of reaction:50℃;③ time of reaction:15min;④ pH of reaction system:4.7.Linear relationship between values of absorbance and mass concentration of formaldehyde was obtained in the range of 0.2-1.0mg· L-1,with detection limit of 5μg·L-1.Values of recovery found by standard addition method were over 98.0%,and values of RSD′s(n= 6)less than 4%.The proposed method was used in the analysis of sample of surface water,giving results of formaldehyde contents in consistency with values found by GB method.

Method and device for quantifying metal complex in plating liquid

Abstract: PROBLEM TO BE SOLVED: To provide a method for quantifying metal complexes, in which metal complexes present in a plating liquid can easily be quantified.SOLUTION: An absorbance curve is defined by the expression represented by Y=A×(1-exp(-(t+t)/T))+A×(1-exp(-(t+t)/T)). The symbol t represents a time variable. The symbol trepresents a constant relating to a color reaction start time. The symbols Aand Aare constants relating to the initial concentration of each of complexes segmented according to a color reaction speed, and the symbols Tand Tare constants relating to the inverse number of the constant of the color reaction speed of each complex. The symbol trepresents a constant provided for correcting a time lag between the time at which a color reaction is started by stirring chelate reagent and copper plating liquid and the time at which an absorbance measurement is started. An absorbance curve can be determined by applying actual data (Y, t) into the defined expression, thereby calculating each constant.

Utilization of 2-Nitro-6-(thiazol-2-yldiazenyl)phenol for Spectrophotometric Determination of Trace Amounts of Copper(II) in Water Samples

Abstract: A simple ultra sensitive and fairly selective non extractive spectrophotometric method for the determination of copper using 2-nitro-6-(thiazol-2-yldiazenyl) phenol (NTDP) has been developed.. The method is based on the color reaction of copper with NTDP at pH 7.1 buffer. The optimal reaction conditions (e.g., reagent concentration, pH and effect of time and temperature) were studied and the analytical characteristics of the method (e.g., limit of detection, limit of quantification, and linear ranges) were obtained. Linearity was obeyed in the range of 0.1-5.0 µg/mL of copper(II) ion and the detection limit of the method was 3.0 ng/mL. The relative standard deviation (RSD) and relative error for six replicate measurements of 2.0 µg/mL Cu(II) were 0.76 % and 1.34 %, respectively. The interference effect of some anions and cations was also tested. The method was applied to the determination of copper(II) in water samples.

Effect of roasting conditions on color characteristic of roasted sesame oil caused by color reaction

Abstract: To analyze the effect of roasting conditions on color reaction of roasted sesame oil,taking the R,G,B values of RGB color mode as evaluation parameters,a series of roasted sesame oil were taken chromogenic reaction by trichloroacetic acid,which were roasted in150~170℃for 10~35min,then the changes of color during 1~7min were analyzed.Results showed that:with the reaction time increasing,the green and blue value decreased significantly,but red value increased slightly.The roasting temperature and time influenced the red,green and blue value,but the difference of color characteristic caused by the roasting temperature and time decreased as the reaction time elapsed.Therefore it was proper for testing the adulterated sesame oil 7min later after chromogenic reaction of trichloroacetic acid.Moreover,the B value of chromogenic reaction could infer the roasting conditions of roasted sesame oil.

Reaction principle of color reaction between Coomassie Brilliant Blue G-250 and benzalkonium chloride

Abstract: Summary The reaction principle of the color reaction between Coomassie Brilliant Blue G-250 (CBB G-250) and benzalkonium chloride at a higher pH (8.53-12.9) was investigated by an experiment and a calculation based on chemical equilibrium. At a higher pH CBB G-250 bound to benzalkonium chloride and produced a pink color. This color reaction was assumed to occur by binding of trivalent anion of CBB G-250 to positively-charged benzalkonium chloride. It was found that the characteristic of the color reaction obtained by an experiment coincides with those calculated based on the chemical equilibrium.

Method and system for measuring test strip

Abstract: The present invention relates to a method for measuring an analyte in a sample, the method comprising the steps of: (a) applying a sample to a reaction device having a color reaction means for inducing a color reaction when a sample is applied thereto, so as to induce a color reaction in the color reaction means, wherein the surface of the reaction device has been modified by means of an appropriate polymer; (b) obtaining a first image, which is a resultant image from the color reaction, by means of a digital imaging apparatus equipped with a flash; and (c) obtaining data, from the first image, for whether or not the analyte is present in the sample. According to the present invention, the data regarding the presence or non-presence or concentration of the analyte in the sample can be conveniently and accurately derived.