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Showing papers on "Color reaction published in 1967"


Journal ArticleDOI
TL;DR: A rapid, reproducible, and sensitive procedure for the determination of phosphate in several biologic materials is described and it is unnecessary to extract the heteropoly acid complex to increase sensitivity or to protect the color complex formed from interference of phosphate hydrolyzed during the process of color formation.
Abstract: A rapid, reproducible, and sensitive procedure for the determination of phosphate in several biologic materials is described Organic phosphate is rapidly converted to orthophosphate by digestion with a nitric acid-calcium ion mixture. The acid destroys the organic material while the calcium ion prevents loss of phosphate or its conversion to an unmeasurable form. Inorganic phosphate can be determined in the presence of labile organic phosphates since phosphate liberated after the color reaction has been initiated cannot interfere by forming further color. Even if phosphate were deliberately added after the color reaction had started, it could not react in the described system. The method may be applied to the determination of phosphate present in ultramicro quantities. It is unnecessary to extract the heteropoly acid complex either to increase sensitivity or to protect the color complex formed from interference of phosphate hydrolyzed during the process of color formation.

356 citations


Journal ArticleDOI
01 Jan 1967-Analyst
TL;DR: The sensitivity of the colour reaction between tin(IV) and catechol violet has been greatly increased by the sensitising action of cetyltrimethylammonium bromide (Iµ662mµ= 95,600).
Abstract: The sensitivity of the colour reaction between tin(IV) and catechol violet has been greatly increased by the sensitising action of cetyltrimethylammonium bromide (Iµ662mµ= 95,600). The sensitisation is also accompanied by a considerable bathochromic shift (107 mµ) of the wavelength of maximum absorption. Full colour development occurs within 5 minutes at pH 2·2, and Beer's law is obeyed down to 0·2 p.p.m. of tin(IV).

40 citations


Journal ArticleDOI
TL;DR: In this article, the conditions for the indophenol reaction, the direct application of it for the determination of blood ammonia, and the interferences of a number of substances for the color development, have been investigated.
Abstract: In an attempt to develope a rapid and simple method for the colorimetric determination of free ammonia in blood, the conditions for the indophenol reaction, the direct application of it for the determination of blood ammonia, and the interferences of a number of substances for the color development, have been investigated. This color reaction was sensitive enough for the direct method, but must be done under the limiting conditions, for the interfereing substances are contained in blood. Interferences of many amino acids for the color development were observed, but the effects differed among different amino acids, and many of substances other than amino acids showed very little or no intereference. Under the conditions applied, neither the amino acids nor other substances in blood interfered the method.

19 citations


Journal ArticleDOI
TL;DR: 2-Methyl-4(5)-nitroimidazoles reacted with Ninhydrin to yield a characteristic green color, a new color reaction for this reagent and appears to involve condensation of the ninhydrin molecule on an active methylene group on an imidazole ring.

16 citations


Journal ArticleDOI
TL;DR: In this paper, a rapid method for the spectrophotometric determination of microgram amount of gallium with 4-(2-pyridylazo)-resorcinol (PAR) in the organic phase after the extraction from a hydrochloric acid solution with isopropyl ether and butyl acetate was described.
Abstract: A rapid method for the spectrophotometric determination of microgram amount of gallium with 4-(2-pyridylazo)-resorcinol (PAR) in the organic phase after the extraction of gallium from a hydrochloric acid solution with isopropyl ether and butyl acetate will be described. A red color is formed in an aliquot of the organic extract by the addition of PAR, pyridine, and sodium acetate in methanol. The complex formed in the organic phase has a maximum absorbance at 510 mμ. The color reaction conforms to Beer’s law, and the molar absorptivity of the complex is estimated to be approximately 100000. The coefficient of the variation of the absorbance measurements on a standard gallium solution at 510 mμ was about 0.8%. A study of the effect of diverse ions showed the method to be highly selective.

6 citations


Journal ArticleDOI
TL;DR: The procedure was especially adjusted to determine small amounts of this amino acid in biological material, and an amount of proline beginning with 2 μg in the sample may be determined.

5 citations


Journal ArticleDOI
TL;DR: In this paper, a determination of lower nitroalkanes was suggested via the colour reaction withm-dinitrobenzene in alkaline solution, via the color reaction with
Abstract: A determination of some lower nitroalkanes is suggested, via the colour reaction withm-dinitrobenzene in alkaline solution.

2 citations



Journal ArticleDOI
TL;DR: A colorimetric method for determination of phenylacetonitrile in amounts down to 0.6μg is described in this article, which depends on the colour reaction withm-dinitrobenzene and potassium hydroxide in 50% methanol.
Abstract: A colorimetric method for determination of phenylacetonitrile in amounts down to 0.6μg is described. It depends on the colour reaction withm-dinitrobenzene and potassium hydroxide in 50% methanol. Microgram amounts of diphenylmethane have been determined by nitration and subsequent treatment with diethylamine, yielding an intense blue colour.

1 citations