Official edition state standards of the union of the ssr

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Official edition
STATE STANDARDS OF THE UNION OF THE SSR
TEST METHODS
I
(ST SEV 5 8 9 4 -8 7 )
GOST 2 7 7 4 9 .0 -8 8 - GOST 27749.3-88
USSR STATE COMMITTEE ON STANDARDS
Moscow
/-U
decor interior
UREA
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© Standards Publishing, 1988 1
accuracy and reagents in quality not lower than domestic ones.
GOST
Sampling - according to GOST 2081-75.
27749.0 - 88
(CT SEV 5894-87)
The method consists in decomposition of urea with sulfuric acid to ammonium
sulfate, neutralization of excess sulfuric acid, addition of formalin, and titration
with sodium hydroxide solution of sulfuric acid released during the reaction in an
amount equivalent to nitrogen.
2.1. Equipment, reagents It is allowed to
use imported equipment according to the class
This International Standard specifies the following methods for the
determination of total nitrogen in urea:
without ammonia stripping (formaldehyde method);
distillation method with the reduction of nitrate nitrogen with chromium and
the mineralization of organic nitrogen (the method is used in case of disagreement
in the results of the evaluation of forms by the aldehyde method).
Cylinders 1(3)-50 according to GOST 1770-74.
Pipettes 2-2-5 according to GOST 20292-74.
Burette 3-2-50 according to GOST 20292-74.
I. SAMPLING
Group L19
Valid from 01.07.90 to
01.07.2000
2 - 2562
carbarnid. Method of nitrogen
content determination
Non-compliance with the standard is punishable by law
STANDARD OF THE UNION OF THE SSR
2. FORMALDEHYDE METHOD
Official edition
Reprint prohibited
UREA
OKSTU 211)9
UDC 661.717.5:006.364:546.17.06
Nitrogen determination methods
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'
_
The correction factor (K) is calculated by the formula
where m is the mass of carbamide, g;
with the maximum weighing limit of 200 g. A
set of weights G-2-210 in accordance with
GOST 7328-82. Electric drying cabinet with control range
Phenolphthalein (indicator), alcohol solution with a mass fraction of
1%; prepared according to GOST
4919.1-77. Mixed acid-base indicator (pH 5.4); prepared according to
GOST 4919.1-77.
Carbamide, free from bnurst, according to GOST 6691-77, analytical
grade, dried at a temperature of 100-105°C for 1
hour. 2.2. Determination of the correction factor for a solution of
sodium hydroxide concentration c (N aO H )=l
mol/dm*. To establish the correction factor for the sodium hydroxide
solution, tests are carried out in accordance with paragraph 2.3, using
urea prepared according to paragraph 2.1.
K is the volume of sodium hydroxide solution with concentration c
(NaOH) = l mol/dm3 used for titration, cm3. 2.3. Procedure
1 g of
the test sample (weighing in grams is
recorded to the fourth decimal place) is placed in a 250 cm3 conical
heat-resistant glass flask and dissolved in 20 cm3 of water. Add 5 cm3
of concentrated sulfuric acid with a pipette, close the flask with a glass
funnel or a hollow pear-shaped glass stopper, carefully heat on an electric
stove to a boil and boil until the evolution of carbon dioxide has completely
ceased and until white fumes of sulfuric acid appear. Then the contents
of the flask are cooled, the stopper is washed with water, collecting the
washings in the flask, 50 cm3 of water are added, 5 drops of a mixed
indicator are neutralized with an excess of acid
General purpose laboratory scales of the 2nd accuracy class
temperatures from 40 to 200*0.
Distilled water according to GOST 6709-72.
Sulfuric acid according to GOST 4204-77 concentrated and a solution
of concentration c (Vs H2S 0 4) -0.5 mol / dm3.
Sodium hydroxide according to GOST 4328-77, a solution of
concentration c (NaOH) = l mol / dm3 is prepared according to GOST
25794.1-83 and a solution of concentration
c (NaOH) - 5 mol / dm *. Formalin technical according to GOST
1625-75, solution with a mass fraction of 30%. before use, neutralized
by phenolphthalene to a slightly pink color.
Y -14.0067-100 ^
46.65-W-1000 46.65-^-10
V - 14.0067
To
S. 2 GOST 27749.0 - $ 8
2
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'
GOST 27749.0-88 S. 3
_V'r^_1l4.00G7-I00.J00 = yy /C-14.0067-10 1000 t
g (KXb-A;n'o G
*
v O 0 0 -.VH(O) '
3. DISTILLATION METHOD
c (NaOH) -1 mol/dm3 used for titration, cm3;
definitions should not exceed 0.2%;
h
where Vi is obs\! sodium hydroxide solution concentration
mol/dm3;
quality and reagents are not lower than domestic ones; the mass of the test
sample shall be 0.2 g; concentration of sulfuric acid c ('/g
volume of sulfuric acid 50 cm
sign.
“
In case of disagreement in the assessment of the determination of nitrogen, di
the result of the determination is rounded to the first decimal place.
K is the correction factor for sodium hydroxide solution with concentration c (NaOH) = 1
mol/dm3; mi is the mass of the test sample of
urea, g; Hm,o is the mass fraction of water in urea, %; 14.0067
is the atomic mass of nitrogen, g/mol. The result of the
determination is taken as the arithmetic mean of the
results of two parallel determinations, the allowable discrepancy between which should not
exceed 0.2% at a confidence level ÿ=0.95. The result of the determination is rounded to the first
decimal.
early with (N aO H)~5 mol/dm*, avoiding its excess. Next, neutralize with a solution of sodium
hydroxide concentration c (NaOH) =
The determination is carried out according to GOST 20851.1-75 (method 9) with the following
2*
stillation method.
I mol/dm3 until the color of the solution changes to gray. 20 cm3 of
formalin solution are added to the neutralized solution, mixed and the solution is allowed to
stand for 2 minutes. Then 5 drops of a solution of phenolphthalein are added and the released
acid is titrated with a sodium hydroxide solution of concentration c (NaOH) - I mol / dm3 until
the color of the solution changes to red, which does not disappear within 1-1.5 minutes. 2.4.
Processing of results The mass fraction of nitrogen (L) in percent is calculated by the formula
it is allowed to use imported equipment according to the class of
blowing clarifications;
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INFORMATION DATA
YOU
fishing
3. The term of the first check is 1999.
4. Corresponds to ST SEV 5894-87 in terms of the method of determination
1. DEVELOPED AND INTRODUCED by the USSR Ministry for the Production
of Mineral Fertilizers
2. APPROVED AND PUT INTO EFFECT by the Decree of the USSR State
Committee for Standards dated 22.06.88 .41 2115
nitrogen
PERFORMERS
5. REFERENCED REGULATORY DOCUMENTS
E. N. Boitsov, E. A. Mishina, V. A. Galperin, N. K. Gavri
ddiz ssyuha
GOST 1625-75 GOST 1770-74
Designation of NTD. on which
2 1
2.1
1
2.1
2.1
2.1
2.1
2.1
2.1
21 3 2.1
;
GOST 2061- 75 GOST 4204-77
GOST 4328- 77 GOST 4919
1 -7 7 GOST 6709-72 GOST
6995 77 GOST 7326-82 GOST
20292- 74 GOST 206SI.I -75
GOST 25794-1 - 83
Partition chuakga number
With GOST 27749.0-86
GOST 27749.0-88
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