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GB/T 8572-2010 PDF in English


GB/T 8572-2010 (GB/T8572-2010, GBT 8572-2010, GBT8572-2010)
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GB/T 8572-2010: PDF in English (GBT 8572-2010)

GB/T 8572-2010
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.080
G 20
Replacing GB/T 8572-2001
Determination of total nitrogen content for compound
fertilizers titrimetric method after distillation
(ISO 5315.1984, MOD)
ISSUED ON. SEPTEMBER 26, 2010
IMPLEMENTED ON. MARCH 1, 2011
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Principle ... 5
4 Reagents and materials ... 6
5 Apparatuses ... 6
6 Analysis steps ... 7
7 Expression of analysis results ... 9
Foreword
This Standard is one of the series of standards for compound fertilizers test methods.
These series of national standards are listed below.
- GB/T 8571-2008 “Preparation of laboratory samples for compound fertilizers”;
- GB/T 8572-2010 “Determination of total nitrogen content for compound fertilizers
titrimetric method after distillation”;
- GB/T 8573-2010 “Determination of available phosphorus content for compound
fertilizers”;
- GB/T 8574-2010 “Determination of potassium content for compound fertilizers
potassium tetraphenylborate gravimetric method”;
- GB/T 8576-2010 “Determination of free water for compound fertilizers - Vacuum
oven method”;
- GB/T 8577-2010 “Determination of free water for compound fertilizers - Karl
Fischer method”;
- GB/T 24890-2010 “Determination of chloride content for compound fertilizers”;
- GB/T 24891-2010 “Determination of particle size for compound fertilizers”.
This Standard modifies and adopts the International standard ISO 5315.1984
“Fertilizers - Determination of total nitrogen content - Titrimetric method after
distillation”.
Main differences between this Standard and ISO 5315.1984 are.
- In the absence of amide nitrogen, the reduction method for nitric acid nitrogen is
modified from chromium powder to nitrogen alloy;
- The standard titration concentration of sodium hydroxide is modified from 0.1 mol/L
to 0.5 mol/L.
This Standard replaces GB/T 8572-2001 “Determination of total nitrogen content for
compound fertilizers titrimetric method after distillation”.
Main difference between this edition and the previous edition is. the standard format is
rewritten according to the rules of standardization work.
This Standard is proposed by China Petroleum and Chemical Industry Association.
This Standard is under the jurisdiction of National Technical Committee on Fertilizers
Determination of total nitrogen content for compound
fertilizers titrimetric method after distillation
1 Scope
This Standard specifies the determination of total nitrogen content for compound
fertilizers.
This Standard does not apply to compound fertilizers with organic compounds greater
than 7 % (except urea, cyanamide compounds).
2 Normative references
The following standards contain provisions which, through reference in this Standard,
constitute provisions of this Standard. For dated reference, subsequent amendments
to (excluding corrections to), or revisions of, any of these publications do not apply.
However, the parties to agreements based on this Standard are encouraged to
investigate the possibility of applying the most recent editions of the standards. For
undated references, the latest edition of the normative document referred to applies.
GB/T 2441.1 Determination of urea - Part 1. Total nitrogen content
GB/T 8571 Preparation of laboratory samples for compound fertilizers
HG/T 2843 Chemical fertilizer products - Standard volumetric standard reagent and
indicator solutions for chemical analysis
3 Principle
In alkaline medium, USE nitrogen alloy to reduce nitric acid nitrogen, and ammonia is
directly distilled; or in acidic medium, REDUCE the nitrate into ammonium salt, in the
presence of mixed catalyst, DIGEST with concentrated sulfuric acid, CONVERT the
organic nitrogen or amide nitrogen and cyanamide nitrogen into ammonium salt, and
ammonia is distilled from alkaline solution. ABSORB the ammonia in excess sulfuric
acid solution, in the presence of methyl red - methylene blue mixed indicator, USE
sodium hydroxide standard titration solution to back titration.
ADD 300 mL of water to the distillation flask; SHAKE to dissolve the specimen; ADD 3
g of nitrogen and explosion-proof matters to the distillation apparatus.
Except that the sodium hydroxide solution (4.8) added is 100 mL and the specimen
shall be put aside for 10 min before heating during the distillation process, the rest
steps are the same as 6.2.1.2.
6.2.3 Sample containing amide nitrogen, cyanamide nitrogen and ammonium
nitrogen
PLACE the distillation flask in the fume hood; carefully ADD 25 mL of sulfuric acid (4.1).
PLUG the pear-shaped glass funnel, and PLACE it on the heating device (5.5) to heat
until sulfuric acid smoke emits for 15 minutes. After the distillation flask is cooled to
room temperature, carefully ADD 250 mL of water.
Except that the sodium hydroxide solution (4.8) added during the distillation process is
100 mL, the rest steps are the same as 6.2.1.2.
6.2.4 Sample containing organic matters, amide nitrogen, cyanamide nitrogen
and ammonium nitrogen
PLACE the distillation flask in the fume hood; ADD 22 g of the mixed catalyst, and
carefully ADD 30 mL of sulfuric acid (4.1); CONTINUE to heat. PLUG the pear-shaped
glass funnel, and PLACE it on the heating device (5.5) to heat.
If there are a lot of bubbles, REDUCE the heating strength until the bubble disappears;
CONTINUE to heat until sulfuric acid smoke emits for 60 minutes or until the solution
turns to be transparent; after the distillation flask is cooled to room temperature,
carefully ADD 250 mL of water.
Except that the sodium hydroxide solution (4.8) added during the distillation process is
120 mL, the rest steps are the same as 6.2.1.2.
6.2.5 Sample containing nitric acid nitrogen, amide nitrogen, cyanamide
nitrogen and ammonium nitrogen
ADD 35 mL of water to the distillation flask; SHAKE to dissolve the sample; ADD 1.2 g
of chromium powder, 7 mL of hydrochloric acid; PUT it aside for 5 min ~ 10 min; PLUG
the pear-shaped glass funnel.
PLACE the distillation flask on a heating device (5.5) in a fume hood; HEAT to boiling
and bubbling for 1 min, and COOL to room temperature; carefully ADD 25 mL of sulfuric
acid (4.1), CONTINUE to heat until sulfuric acid smoke emits for 15 minutes; after the
distillation flask is cooled to room temperature, carefully ADD 400 mL of water.
Except that the sodium hydroxide solution (4.8) added during the distillation process is
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Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.