Showing papers on "Color reaction published in 2002"
TL;DR: The method had good selectivity and could be applied to direct spectrophotometric determination of vitamin B(1) in aqueous phase without using organic solvent extraction and was simple and rapid.
52 citations
TL;DR: In this article, a simple, accurate, fast, selective and sensitive assay of cyanide based on its reaction with 2,2-dihydroxy-l,3-indanedione at basic pH is proposed.
33 citations
TL;DR: In this article, a new synthesized chromogenic reagent N-dodecyl-N′-(sodium p-amino-benzenesulfonate)-thiourea (DOPT) was developed for determination of copper and palladium.
Abstract: Highly sensitive spectrophotometric methods for determination of copper and palladium by a new synthesized chromogenic reagent N-dodecyl-N′-(sodium p-amino-benzenesulfonate)-thiourea (DOPT) were developed. In the presence of CTMAB and NaAc-HAc buffer solution, under the optimum conditions for color reaction of copper and palladium with DOPT, their molar absorptivities are e300.4 nm = 1.56 × 105 l mol−1 cm−1 at 300.4 nm for copper and e296.0 nm = 7.41 × 104 l mol−1 cm−1 at 296.0 nm for palladium. Microamounts of copper and palladium in samples were satisfactorily determined by the methods.
23 citations
TL;DR: It is proposed that the purple color produced under these reaction conditions is that of 2-cyano-1,2,3-trihydroxy-2H indene, and suitable for the determination of hydrogen cyanide in the environment and free cyanide ions in water, blood, urine, serum, etc.
Abstract: A novel reaction of cyanide with 2,2-dihydroxy-1,3-indanedione in the presence of sodium carbonate is described. It is highly selective and sensitive, and suitable for the determination of hydrogen cyanide in the environment and free cyanide ions in water, blood, urine, serum, etc. As little as 1.25×10–7 mol L–1 CN– (3.25×10–9 g mL–1 cyanide) can be determined by use of this reaction. The color system obeys Beer's law in the range 10 ng mL–1 to 1.0 µg mL–1 at 510 nm. The molar absorptivity was 8.0×104 L mol–1 cm–1 for a solution of concentration 0.2 µg mL–1. All other important analytical properties of the reaction have been studied. It is proposed that the purple color produced under these reaction conditions is that of 2-cyano-1,2,3-trihydroxy-2H indene.
19 citations
TL;DR: Under the optimum conditions the total amount of polyphenols could be determined within a concentration range of 36 to 544 mg L–1, and with a sensitivity of 344 L mol–1 cm–1 and an RSD <1.1%.
Abstract: A new flow-injection analytical procedure is proposed for the determination of the total amount of polyphenols in wines; the method is based on the formation of a colored complex between 4-aminoantipyrine and phenols, in the presence of an oxidizing reagent. The oxidizing agents hexacyanoferrate(III), peroxodisulfate, and tetroxoiodate(VII) were tested.
16 citations
TL;DR: In this article, a color reaction between o-Carboxylbenzenediazoaminoazobenzene (o-CDAA) and nickel(II) was used for the determination of trace nickel.
Abstract: A highly sensitive and relatively interference-free spectrophotometric method for the determination of nickel is described. The method is based on color reaction between o-Carboxylbenzenediazoaminoazobenzene (o-CDAA) and nickel(II). The absorbance (at λmax = 540 nm) is linear up to 0.24 µg ml−1 of nickel(II) in borax buffer solution (pH = 10) with a repeatability(RSD) of 1.0% at a concentration of 0.2 µg ml−1. The molar absorptivity of Ni-o-CDAA-TritonX-100 is 3.3 × 105 l mol−1 cm−1, its limit of quantification and the limit of detection were found to be 0.74 and 0.22 ng ml−1 respectively, it gives a better sensitivity than other reagents published. The influence of reaction variables and the effect of interfering ions are reported; most of metal ions in food can be tolerated in considerable amounts. Only zinc may interfere with determination of trace nickel, but it can be eliminated by using a prior separation with sulfhydryl dextran gel adsorbent easily. Moreover, the synthesis of derivatives o...
10 citations
Patent•
13 Sep 2002
TL;DR: In this article, a temperature-sensitive metachromatic and color-memorizing microcapsule pigment exhibits a hysteresis breadth of 20-60°C in relation to a color density-temperature curve to cause a color change.
Abstract: PROBLEM TO BE SOLVED: To find out a new reaction medium and to extend the degree of freedom of selection in a thermochromic material exhibiting color-memorizing effects by selecting a specific compound as the reaction medium for a color reaction according to a transfer reaction of electrons. SOLUTION: A temperature-sensitive metachromatic and color-memorizing microcapsule pigment exhibits a hysteresis breadth (ΔH) of 20-60°C in relation to a color density-temperature curve to cause a color change. The pigment is obtained by encapsulating a temperature-sensitive metachromatic and color-memorizing composition composed of (a) an electron-donating coloring organic compound, (b) an electron-accepting compound and (c) a homogeneous compatibilized substance of diesters composed of a ≥12C saturated straight-chain dibasic acid and a monohydric alcohol having an aromatic ring in the molecule as the reaction medium for controlling the color reaction of (a) and (b) in a microcapsule. COPYRIGHT: (C)2004,JPO
9 citations
TL;DR: An excellent method for spectrophotometric determination of trace lead in industrial samples has been developed in this article, which is based on the reaction of lead(II) with new reagent 2-(2-sulfophenylazo)-7-(2,6-dibromo-4-methyphenylazo)1,8-dihydroxynaphthalene-3, 6-disulfonic acid(SDBM).
Abstract: An excellent method for spectrophotometric determination of trace lead in industrial samples has been developed. The method is based on the reaction of lead(II) with new reagent 2-(2-sulfophenylazo)-7-(2,6-dibromo-4-methyphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid(SDBM). Under optimal conditions, SDBM reacts with lead(II) to give a 1 : 2 blue complex in a phosphoric acid media, which has an maximum peak at 630 nm; 0–20 µg of lead(II) obeyed Beer's law in 25 mL solution. The color reaction is instantaneous and the absorbance stable for 24 h; its the apparent molar absorption coefficient, Sandell's sensitivity, the limit of detection and the limit of quantification were found to be 1.07 × 105 L mol−1 cm−1, 1.94 ng cm−2, 3.12 ng mL−1 and 10.0 ng mL−1 respectively. Effect of foreign ions have been examined in detail. The experiment indicated that most of metal ions studied can be tolerated in considerable amounts, especially transition metal ions such as Ag(I), Fe(III), Co(II), Ni(II), Cu...
7 citations
TL;DR: The optimum acidity and concentration of reagents were established and the effect of several metal ions usually present in real samples, e.g. waste water, was examined to assess interference.
Abstract: A kinetic method for the determination of aromatic amines is reported. The method involves the formation of an azo dye between 1-(4-hydroxy-6-methylpyrimidin-2-yl)-3-methylpyrazolin-5-one and a diazonium salt formed from the amine in the presence of nitrite in weakly acidic media. The reaction is monitored via the initial rate of change of the absorbance of the azo dye at 420 nm, because this is proportional to the aniline concentration. The optimum acidity and concentration of reagents were established. The concentration ranges for which the calibration lines are linear are quite large. Detection limits were estimated. The effect of several metal ions usually present in real samples, e.g. waste water, was examined to assess interference.
4 citations
Journal Article•
TL;DR: In this paper, the color reaction of Fuchsin Basic and anionic surfactant is studied in the NH 3-NH 4Cl solution of pH 9 5, and the method has been applied to determine the trace anion surfactants in some samples.
Abstract: The color reaction of Fuchsin Basic and anionic surfactant is studied in this paperIn the NH 3-NH 4Cl solution of pH 9 5,Fuchsin Basic reacts directly with anionic surfactants to form a red ionassociate compounds with maximum absorption in wavelength of 520 nmThe apparent molar absorptivity of the ionassociate compounds is 2 36×10 4L·mol -1 ·cm -1 Beers law is obeyed in the range of 8 3—41 8μg/ml of SDBSThe method has been applied to determine the trace anionic surfactants in some samples with satisfactory results
2 citations
Patent•
19 Nov 2002TL;DR: In this article, an ATP measuring reagent was proposed which rendered possible visual determination by amplifying the reaction to form glucose 6-phosphate from glucose through the joint use of ATP contained in a sample and acetyl phosphate contained in the reagent with glucokinase and acetate kinase.
Abstract: The object of the invention is to provide a handy type visually determinable ATP measuring reagent which can be easily handled and has good measuring sensitivity. The invention is an ATP measuring reagent which rendered possible visual determination by amplifying the reaction to form glucose 6-phosphate from glucose through the joint use of ATP contained in a sample and acetyl phosphate contained in the reagent with glucokinase and acetate kinase contained in the reagent, and further leading it to a visualizable color reaction by the combination of glucose-6-phosphate dehydrogenase and diaphorase.
Journal Article•
TL;DR: Based on the color reaction of 2-(2-quinolinylazo)-1,5-dihydroxidebenzene (QADHB) with copper and the solid phase extraction of its colored complex with Waters Porapak ○R Sep-Park-C 18 cartridge, a new method for the determination of trace copper (Ⅱ) is studied as mentioned in this paper.
Abstract: Based on the color reaction of 2-(2-quinolinylazo)-1,5-dihydroxidebenzene (QADHB) with copper (Ⅱ) and the solid phase extraction of its colored complex with Waters Porapak ○R Sep-Park-C 18 cartridge, a new method for the determination of trace copper (Ⅱ) is studied. In the medium of CTMAB and presence of pH=4.0 buffer solution, QADHB can reacts with copper (Ⅱ) to form a stable 2∶1 complex. The colored complex can be extracted by C 18 cartridge, eluted by ethanol, and then determined by spectrophotometry at 560 nm. Beer's law is obeyed in range of 0~1.0 μg/mL. This method can be applied to the determination microamount of copper in water with satisfactory results.
TL;DR: In this paper, a new method for the determination of chloral hydrate in semi-bright nickel baths by visible spectroscopy is proposed, based on the colour reaction between chloralin hydrate and barbituric acid at 60 °C.
Abstract: A new method for the determination of chloral hydrate in semi-bright nickel baths by visible spectroscopy is proposed. The method is based on the colour reaction between chloral hydrate and barbituric acid at 60 °C. It is a slow reaction and samples are taken each minute whilst the reaction is carrying on. These samples are cooled down in order to stop the reaction before measuring the absorbance at 454 nm. In this way a plot of absorbance against time can be obtained. This plot presents two parts, a linear plot for 7 minutes and a plateau between 8 and 12 minutes. These behaviours allow us to use two kinds of analyses: classical and kinetic methods.
Journal Article•
TL;DR: The authors showed that triethylamine (6f) is a phenylogous amine that reacts with 1 to form the blue colored 4-(diethylamino-phenyl)-1,2-naphthoquinone (8).
Abstract: Sodium 1,2-naphthoquinone-4-sulphonate (1) reacts with trialkylamines 6a, b by N-desalkylation to give red colored 4-dialkyamino-1,2-naphthoquinones 3a, b. N,N-Diethylaniline (6f), a phenylogous amine, reacts with 1 to form the blue colored 4-(diethylamino-phenyl)-1,2-naphthoquinone (8). 2,3-Dihalogeno-1,4-naphthoquinones 15A/B produce with triethylamine (6a) the red N-desalkylation products 17A/Ba and the blue colored dehydrogenation products 18A/B. The reactions from trialkylamines 6b-g indicate that only ethyl functions may be dehydrogenated. 2,3-Dihalogeno-1,4-naphthoquinones 15A/B form with N,N-Diethylaniline (6f) blue violet colored CT-complexes and with diethylcyclohexylamine (6g) only blue colored 2-aminovinyl-3-halogeno-1,4-naphthoquinones 20A/B.
Patent•
26 Dec 2002
TL;DR: In this paper, an indicator composition utilizing a detection reaction of an aldehyde using amines or an amino acid, ascorbic acid and/or its analog are included to control an excess reaction.
Abstract: PROBLEM TO BE SOLVED: To provide a composition suppressing a color reaction properly, and suitable for an indicator for effectiveness of an aldehyde-based fungicide, concerning the color reaction for detection of aldehydes for use of the fungicide mainly composed of the aldehyde-based fungicide. SOLUTION: In this indicator composition utilizing a detection reaction of an aldehyde using amines or an amino acid, ascorbic acid and/or its analog are included to control an excess reaction. Preferably, hydroxylamine and/or its salt, or sulfurous acid and/or its salt are included additionally. The indicator composition is impregnated into a support such as filter paper or the like stuck on a plastic board, to shape a stick as a commodity in a form preserved under oxygen interruption. A color chip for effectiveness screening is attached to a commodity rapping form.
Patent•
20 Dec 2002
TL;DR: A universally applicable color indicator system contains a biosorbent impregnated with a chemical as indicator reagent giving a distinct color reaction on contact with a substance to be indicated.
Abstract: A universally applicable color indicator system contains a biosorbent impregnated with a chemical as indicator reagent giving a distinct color reaction on contact with a substance to be indicated.