Showing papers on "Color reaction published in 1972"
01 Jan 1972
356 citations
01 Jan 1972
TL;DR: In this article, the authors used 35% water, 50% glacial acetic acid, and 15% o-toluidine to obtain stable coloration at least for 24 hours.
Abstract: plasma glucose without deproteinization. This reagent which was prepared in the preliminary experiment consisted of 35% water, 50% glacial acetic acid, and 15% o-toluidine, while the contents of boric acid and thiourea were the same as the original reagent. Although this reagent enabled the authors to obtain a stable coloration at least for 24 hrs. when heated for 15 min., a slight turbidity was also
318 citations
TL;DR: A direct colorimetric method is described for determination of hippuric acid in urine that follows the Beer-Lambert law up to 1 mg/ml.
Abstract: A direct colorimetric method is described for determination of hippuric acid in urine. Hippuric acid dissolved in pyridine—water (1:1) produces a color ( Amax = 410 nm) when benzenesulfonyl chloride is added. With the method based on this color reaction, urinary hippuric acid follows the Beer-Lambert law up to 1 mg/ml.
69 citations
TL;DR: In this article, the color changes of Na, Ca, and Cu-bentonite-benzidine pastes were observed for color changes upon freezing at −5°C, −15°C and −21°C.
Abstract: Changes in the color of Na, Ca, and Cu-bentonite-benzidine pastes were observed for color changes upon freezing at −5°C, −15°C, and −21°C. At −5°C no color change could be detected. At −15°C and −21°C, when the benzidine/bentonite ratio (W/W) was in the range of approximately 0.0003 to 0.003, the pastes' colors changed from blue or pale blue to green or bluish green. Reflectance measurements of Na-bentonite-benzedine paste at −150°C were carried out in a specially designed cell. These measurements show that in addition to the color change, the reflectivity of the frozen paste became higher upon freezing to −150°C, presumably because of the formation of ice crystals. The explanation of the color changes is based on the assumption that the (blue) monovalent and the (yellow) divalent cations coexist in the frozen paste at different zones on the bentonite surface.
10 citations
TL;DR: A new reagent, Carboxynitrazo, gives a colour reaction with some rare earth elements and a possible procedure for the determination of lanthanum in the presence of ytterbium is discussed.
9 citations
TL;DR: Shikimic acid heated with p-hydroxybenzaldehyde and concentrated sulfuric acid produces an intense and stable purple-violet dye with absorption maximum at 590 nm, and can be quantitatively determined in the range from 15 to over 120 ng (0.1 to 0.7 μmole/ml).
8 citations
TL;DR: Tropolone forms a water-soluble yellow complex with rhodium-(III), which is extractable into chloroform containing pyridine as mentioned in this paper. But, the more suitable wave-length for the determination is 420 nm at which there is practically no absorption by the reagent.
Abstract: Tropolone forms a water-soluble yellow complex with rhodium-(III), which is extractable into chloroform containing pyridine. Although λmax of the complex lies at 390 nm, the more suitable wave-length for the determination is 420 nm at which there is practically no absorption by the reagent. The composition of the complex, as determined by Job's and logarithmic methods, comes out to be 1 ∶ 2. The pH range for maximum colour development is 5.5–6.3. Beer's law is followed up to 9.0 ppm and sensitivity of the colour reaction at 420 nm is 0.009μg Rh/cm2. The effect of various foreign ions has been investigated. With simple modifications, the method becomes highly selective.
3 citations
3 citations
TL;DR: In this article, a simple method for the determination of gold with ascorbic acid over a fairly wide range of pH has been developed, which obeys Beer's law in the range 20−500 μg of gold.
2 citations
TL;DR: In this paper, a new spectrophotometric method for the determination of palladium was proposed, which is specific for palladium and has 1 μg/ml as visual limit of identification.
1 citations
TL;DR: In this paper, imidazoline was benzoylated with 3, 5-dinitrobenzoyl chloride and sodium carbonate buffer by Schotten-Baumann reaction to develop a deep red color.
Abstract: Imidazoline was benzoylated with 3, 5-dinitrobenzoyl chloride and sodium carbonate buffer by the usual Schotten-Baumann reaction to develop a deep red color. The reaction was carried out in the dark and the solution after addition of 3, 5-dinitrobenzoyl chloride to imidazoline was immediately brought to a slightly acidic or neutral pH by which the color developed. This coloration was applied for the determination of naphazoline in pharmaceuticals and the mechanism of this reaction was also investigated.
TL;DR: A new colorimetric method is presented based on the determination of 2-oxoglutaric acid formed in the enzyme reaction by means of the previously established selective color reaction of the acid, suitable to assay a large number of samples with a wide range of activity at the same time.
Abstract: A new colorimetric method is presented for the determination of serum isocitric dehydrogenase activity. This is based on the determination of 2-oxoglutaric acid formed in the enzyme reaction by means of the previously established selective color reaction of the acid. The method gives reliable results and is suitable to assay a large number of samples with a wide range of activity at the same time with 50μl of sample.
TL;DR: Two main coloring matters were isolated in crystalline forms in the color reaction of formaldehyde and diazotized sulfanilamide as mentioned in this paper, and they were identified as 1, 3, 5-tri-(p-sulfamo yr) phenylformazan and 1, 5 -di-(p -sulfamoyl), respectively.
Abstract: Two main coloring matters were isolated in crystalline forms in the color reaction of formaldehyde and diazotized sulfanilamide. Their structures were determined as 1, 3, 5-tri-(p-sulfamo yr) phenylformazan and 1, 5-di-(p-sulfamoyl) phenylformazan.Similarly, two main coloring matters of the reaction of formaldehyde with diazotized p-aminobenzoic acid were obtained as their methyl esters. They were identified as 1, 3, 5-tri-(p-carbomethox y) phenylformazan and 1, 5-di-(p-carbomethoxy) phenylformazan.
TL;DR: In this article, a sensitive and convenient test for benzoate is proposed, in which the anion gives a colour reaction with lanthanum nitrate in the presence of iodine and ammonia.
Abstract: A sensitive and convenient test is proposed for benzoate, in which the anion gives a colour reaction with lanthanum nitrate in the presence of iodine and ammonia. Benzoate has been identified in the presence of salicylate by thin-layer chromatography.
01 Mar 1972
TL;DR: The 2.2′-hydroxy chalcone gave an intense orange-yellow color with beryllium in the pH range 5·5−6·2 as discussed by the authors.
Abstract: 2′-Hydroxy chalcone gave an intense orange-yellow color with beryllium in the pH range 5·5–6·2. The limits of identification and dilution were 0·125γ and 1:4 × 105 respectively. A detailed spectro-photometric investigation of the color reaction was carried out. The complex obeyed Beer’s Law in the concentration range of 0·5–6·0p.p.m. at 460 nm. In the complex the ratio of metal to ligand is 1:2. The instability constant of the complex was 2·176 × 10−6 at 28°. Oxalate, tartrate, citrate and fluoride interfered. The tolerance limits of iron, aluminium, chromium, uranium, thorium and vanadium are reported.