Experiment Station Record, Volume 67, July-December, 1932 Page: 8
xix, 895 p. ; 24 cm.View a full description of this book.
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8 EXPERIMENT STATION RECORD [Vol. 67
Medical School presents in working detail modifications of the Kolthoff method
for the precipitation of sodium as the triple acetate of uranyl, zinc, and sodium
(E. S. R., 58, p. 608). The removal of phosphate (which interferes by precipitating
the reagent) by means of uranyl salts is noted as yielding a precipitate
difficult to handle and causing the sodium determination to give low results.
Magnesia mixture has given satisfactory results, but the authors found powdered
calcium hydroxide more desirable for use as phosphate precipitant in the
work here reported upon.
A new color reaction for soluble organic sulfur compounds, I. W. GnOTE
(Jour. Biol. Chem., 93 (1931), No. 1, pp. 25-30).-In a study of the reaction of
organic hydrosulfyl compounds it was found that by making the test in a
saturated solution of sodium bicarbonate, pH 8 to 9, instead of using the more
commonly employed carbonate or hydroxide, the interference of ketones, aldehydes,
creatinine, thio ethers, and many of the alkaloids could be eliminated
almost entirely. With the use of potassium cyanide as a reducing agent, the
test could be extended to the organic disulfides.
In the course of the experiments noted it was further observed that a solution
of sodium nitroferricyanide ("nitroprusside"), "previously exposed to
light for some time, gives an intense blue color with compounds of the thiourea
type in addition to the normal purple-red color with C-S-H." A number of derivatives
of sodium nitroferricyanide were then prepared, with a view to reproducing
the substance formed under the influence of sunlight.
"Reduction of sodium nitroprusside in alkaline solution by means of hydroxylamine
hydrochloride yields a yellow compound, sodium aquoferrocyanide,
Na3Fe( CN) 5.H20.
. . . Treatment of this yellow compound with bromine water in neutral solution
gives an intense purple compound . . . This compound was found to give an
intense blue with thiourea after several minutes, more quickly on warming, but
not as promptly as the material prepared by sunlight. . . . On standing in solution
for some time in the presence of sodium bicarbonate, the purple color of
sodium aquoferricyanide is changed to a dark yellow-brown. This yellow compound
reacts instantly with thiourea to give a blue color but does not give the
usual nitroprusside reactions with mercaptans, etc ....
"A satisfactory test solution giving both the new reaction with C=S compounds
and the usual nitroprusside reactions may be prepared as follows:
0.5 g of sodium nitroprusside (sodium nitroferricyanide) is dissolved in 10 cc
of water at room temperature, 0.5 g of hydroxylamine hydrochloride is added,
folowed by 1 g of sodium bicarbonate. After evolution of gas has ceased, 2
drops of bromine are added. Excess bromine is removed by aeration and the
dark greenish or black-brown solution filtered and made up to 25 cc. This
solution behaves like that prepared by exposure of sodium nitroprusside to sunlight
and contains a mixture of several compounds, one of which reacts with the
thiourea type and another like ordinary nitroprusside. The solution is stable
for about 2 weeks, gradually losing reactivity toward C=S. No further purification
is necessary for general test use."
By means of this reagent it was shown to be possible to distinguish soluble
organic sulfur compounds of the hydrosulfyl, disulfide, and thiocarbonyl types
from other types and from one another. The new reagent could also be used for
quantitative colorimetric estimation of thiosulfate, "thiocynanate, thiourea,
and other compounds of the C=S type."
The determination of uric acid in the study of avian nutrition, J. L. ST.
JOHN and 0. JOHNSON (Jour. Biol. Chem., 92 (1931), No. 1, pp. 41-45).-In
this paper from the Washington College Experiment Station the authors
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United States. Office of Experiment Stations. Experiment Station Record, Volume 67, July-December, 1932, book, 1933; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5089/m1/27/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.