GB/T 22923-2008 English PDF (GB/T22923-2008)

GB/T 22923-2008: Determination of nitrogen, phosphorus and potassium for fertilizers by auto analyzer
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GB/T 22923-2008
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 65.080
G 20
Determination of nitrogen, phosphorus and
potassium for fertilizers by auto analyzer
ISSUED ON. DECEMBER 31, 2008
IMPLEMENTED ON. AUGUST 01, 2009
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 ... 4 
2 Normative references ... 4 
3 Test methods ... 4 
Foreword
This standard was proposed by the China Petroleum and Chemical Industry
Association.
This standard shall be under the jurisdiction of the National Standardization
Technical Committee on Fertilizer and Soil Conditioner (SAC/TC 105).
The drafting organizations of this standard. National Fertilizer Quality
Supervision and Inspection Center (Shanghai), Tianji Coal Chemical Industry
Group Co., Ltd., Shanghai Shengsheng Automation Analysis Instrument Co.,
Ltd.
The main drafters of this standard. Zhang Minghong, Zhang Jiahong, Duan
Lulu, Li Lihua, He Jianzhong, Wu Juan, Liu Wanqing.
This standard is the first release.
Determination of nitrogen, phosphorus and
potassium for fertilizers by auto analyzer
1 Scope
This standard specifies the method for the determination of nitrogen,
phosphorus and potassium in fertilizers using auto analyzers.
This standard applies to the determination of nitrogen, phosphorus and
potassium in fertilizers.
Flow analyzer method is not applicable to the fertilizer containing organic
matters, AND the nitrogen content determination method is not applicable to
the fertilizer containing nitrogen of more than 40%.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For the dated references, the subsequent
amendments (excluding corrections) or revisions do not apply to this Standard;
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
HG/T 2843 Chemical fertilizer products - Standard volumetric, standard,
reagent and indicator solutions for chemical analysis
3 Test methods
The reagents, solutions and water used in this standard shall comply with the
requirements of HG/T 2843, unless otherwise their specifications and
preparation methods are indicated.
3.1 Determination of nitrogen content - Nitrogen analyzer method
3.1.1 Principle
The nitrate in the acidic medium is reduced into the ammonium salt, which is
digested by concentrated sulfuric acid in the presence of a mixed catalyst to
convert the amide nitrogen into an ammonium salt. Ammonia is distilled from
the alkaline solution, AND the ammonia is absorbed with boric acid absorption
solution AND then titrated with the sulfuric acid standard titration solution.
Automatic nitrogen analyzer can integrate such functions as distillation,
titration, result display, or calculation, etc., to finish determination automatically
and quickly.
WEIGH the sample of total nitrogen content of about 100 mg and nitrate
nitrogen content of less than 25 mg (accurate to 0.0002 g) in the digestion tube;
ADD 0.5 g of chromium powder; USE a small amount of water to wash the
tube wall; PLACE the digestion tube in a ventilation cabinet; ADD 5 mL of
hydrochloric acid in the digestion tube; LET it stand at room temperature for at
least 5 min, (BUT not exceeding 10 min). PLACE the digestion tube in the
digestion furnace which has been heated to 300 °C in advance; INSERT in the
pear-shaped glass funnel; HEAT to boil it for 1 min ~ 2 min; PAY attention to
avoid drying it; COOL it down; RINSE the funnel and digestion tube wall.
3.1.4.3 Treatment of sample containing amide nitrogen and ammonium
nitrogen
WEIGH the sample containing nitrogen of about 100 mg (accurate to 0.0002 g)
into the digestion tube; USE a small amount of water to wash the tube wall;
PLACE the digestion tube in a ventilation cabinet; ADD 10 mL of sulfuric acid
and 0.5 g of mixed catalyst; INSERT the pear-shaped glass funnel; HEAT it for
1 h in the digestion furnace at 340 °C; PAY attention to avoid drying it; COOL it
down; RINSE the funnel and digestion tube wall.
3.1.4.4 Treatment of sample containing nitrate nitrogen and amide
nitrogen
WEIGH the sample of total nitrogen content of about 100 mg and nitrate
nitrogen content of less than 25 mg (accurate to 0.0002 g) in the digestion tube;
ADD 0.5 g of chromium powder; USE a small amount of water to wash the
tube wall; PLACE the digestion tube in a ventilation cabinet; ADD 5 mL of
hydrochloric acid in the digestion tube; LET it stand at room temperature for at
least 5 min, (BUT not exceeding 10 min). PLACE the digestion tube in the
digestion furnace which has been heated to 300 °C in advance; INSERT in the
pear-shaped glass funnel; HEAT to boil it for 1 min ~ 2 min; PAY attention to
avoid drying it; COOL it down; carefully ADD 10 mL sulfuric acid and 0.5 g of
mixed catalyst; PLACE it into the digestion furnace again; INCREASE the
temperature to 340 °C; HEAT it until the solution color changes into purple;
PAY attention to avoid drying it; COOL it down; RINSE the funnel and digestion
tube wall.
3.1.4.5 Treatment of organic-inorganic compound fertilizer sample
containing no nitrate nitrogen
WEIGH the sample containing nitrogen of about 100 mg (accurate to 0.0002 g)
into the digestion tube which had been dried in advance; PLACE the digestion
tube into the ventilation cabinet; ADD 10 mL of sulfuric acid and 0.5 g of mixed
catalyst; INSERT the pear-shaped glass funnel; LET it stand for 10 min;
PLACE the digestion tube over the digestion furnace to slowly heat it (if the
reaction is intense to produce too much foam, MOVE it away from the
digestion tube to cool it down for a moment); after the intense reaction finishes,
INCREASE the temperature of the digestion furnace to 340 °C to continue
digestion, until the solution is colorless or in light color. PAY attention to avoid
drying it; COOL it down; RINSE the funnel and digestion tube wall.
3.2.1.3.2 Automatic digestion furnace, the temperature can be controlled within
the range of 340 °C ± 5 °C;
3.2.1.3.3 Electric heating plate, the power is about 1.8 kW ~ 2.4 kW;
3.2.1.3.4 Digestion tube, the volume is about 350 mL;
3.2.1.3.5 Flow analyzer, it has the ammonium nitrogen channel and automatic
injection device, with the ammonium nitrogen detection lower limit of 0.2 mg/L.
3.2.1.4 Preparation of sample solution
MAKE parallel determinations against two set of materials.
PREPARE laboratory samples in accordance with the corresponding product
standards.
3.2.1.4.1 Treatment of sample containing ammonium nitrogen only. WEIGH
the sample containing about 100 mg of nitrogen (accurate to 0.0002 g) into a
250-mL conical flask; ADD about 100 mL of water and 5 mL of sulfuric acid;
HEAT to boil it for 15 min; COOL it down; quantitatively TRANSFER it to a
250-mL volumetric flask; USE water to dilute it to the mark; MIX it uniformly;
dry FILTER it; DISCARD the initial filtrate.
3.2.1.4.2 Treatment of sampling containing amide nitrogen and ammonium
nitrogen. Treatment of sample containing ammonium nitrogen only. WEIGH
the sample containing about 100 mg of nitrogen (accurate to 0.0002 g) into a
digestion tube; USE a small amount of water to rinse the tube wall; PLACE the
digestion tube into the ventilation cabinet; ADD 5 mL of sulfuric acid; PLACE
the digestion tube on the digestion furnace; HEAT it at 340 °C for 1 h;
quantitatively TRANSFER it to a 250 mL volumetric flask; USE water to dilute it
to the mark; MIX it uniformly; dry FILTER it; DISCARD the initial filtrate.
3.2.1.4.3 Preparation of blank solution. except for not adding sample, the rest
procedures are same as the preparation of sample solution.
3.2.1.5 Analytical procedures
3.2.1.5.1 Drawing of working curves
PIPETTE 0 mL, 0.5 mL, 1.0 mL, 2.0 mL and 4.0 mL of ammonium nitrogen
(NH4+-N) standard solution respectively into five 100 mL volumetric flask; USE
the corresponding blank solution to dilute it to the mark; MIX it uniformly. AND
the concentrations of this standard solution are 0, 50 mg/L, 100 mg/L, 200
mg/L, and 400 mg/L, respectively.
Before making the determination, with reference to the instrument instruction
manual, SELECT the best working parameters.
Then, PLACE the solution sucker of the flow analyzer into the buffer solution,
sodium salicylate solution, and dichloroisocyanic acid solution respectively. At
PREPARE laboratory samples in accordance with the corresponding product
standards.
WEIGH the sample contain the nitrate nitrogen of about 50 mg (accurate to
0.0002 g); PLACE it into a 250mL-conical flask; ADD about 100 mL of water;
HEAT to boil it for 15 min; COOL it down; quantitatively TRANSFER it to a
250-mL volumetric flask; USE water to dilute it to the mark; MIX uniformly; dry
FILTER it; DISCARD the initial part of the filtrate.
Preparation of blank solution. except for not adding sample, the rest
procedures are same as the preparation of sample solution.
3.2.2.5 Analytical procedures
3.2.2.5.1 Drawing of working curves
PIPETTE 0 mL, 1.0 mL, 2.0 mL, 4.0 mL, and 8.0 mL of nitrate nitrogen...
GB/T 22923-2008
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 65.080
G 20
Determination of nitrogen, phosphorus and
potassium for fertilizers by auto analyzer
ISSUED ON. DECEMBER 31, 2008
IMPLEMENTED ON. AUGUST 01, 2009
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 ... 4 
2 Normative references ... 4 
3 Test methods ... 4 
Foreword
This standard was proposed by the China Petroleum and Chemical Industry
Association.
This standard shall be under the jurisdiction of the National Standardization
Technical Committee on Fertilizer and Soil Conditioner (SAC/TC 105).
The drafting organizations of this standard. National Fertilizer Quality
Supervision and Inspection Center (Shanghai), Tianji Coal Chemical Industry
Group Co., Ltd., Shanghai Shengsheng Automation Analysis Instrument Co.,
Ltd.
The main drafters of this standard. Zhang Minghong, Zhang Jiahong, Duan
Lulu, Li Lihua, He Jianzhong, Wu Juan, Liu Wanqing.
This standard is the first release.
Determination of nitrogen, phosphorus and
potassium for fertilizers by auto analyzer
1 Scope
This standard specifies the method for the determination of nitrogen,
phosphorus and potassium in fertilizers using auto analyzers.
This standard applies to the determination of nitrogen, phosphorus and
potassium in fertilizers.
Flow analyzer method is not applicable to the fertilizer containing organic
matters, AND the nitrogen content determination method is not applicable to
the fertilizer containing nitrogen of more than 40%.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For the dated references, the subsequent
amendments (excluding corrections) or revisions do not apply to this Standard;
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
HG/T 2843 Chemical fertilizer products - Standard volumetric, standard,
reagent and indicator solutions for chemical analysis
3 Test methods
The reagents, solutions and water used in this standard shall comply with the
requirements of HG/T 2843, unless otherwise their specifications and
preparation methods are indicated.
3.1 Determination of nitrogen content - Nitrogen analyzer method
3.1.1 Principle
The nitrate in the acidic medium is reduced into the ammonium salt, which is
digested by concentrated sulfuric acid in the presence of a mixed catalyst to
convert the amide nitrogen into an ammonium salt. Ammonia is distilled from
the alkaline solution, AND the ammonia is absorbed with boric acid absorption
solution AND then titrated with the sulfuric acid standard titration solution.
Automatic nitrogen analyzer can integrate such functions as distillation,
titration, result display, or calculation, etc., to finish determination automatically
and quickly.
WEIGH the sample of total nitrogen content of about 100 mg and nitrate
nitrogen content of less than 25 mg (accurate to 0.0002 g) in the digestion tube;
ADD 0.5 g of chromium powder; USE a small amount of water to wash the
tube wall; PLACE the digestion tube in a ventilation cabinet; ADD 5 mL of
hydrochloric acid in the digestion tube; LET it stand at room temperature for at
least 5 min, (BUT not exceeding 10 min). PLACE the digestion tube in the
digestion furnace which has been heated to 300 °C in advance; INSERT in the
pear-shaped glass funnel; HEAT to boil it for 1 min ~ 2 min; PAY attention to
avoid drying it; COOL it down; RINSE the funnel and digestion tube wall.
3.1.4.3 Treatment of sample containing amide nitrogen and ammonium
nitrogen
WEIGH the sample containing nitrogen of about 100 mg (accurate to 0.0002 g)
into the digestion tube; USE a small amount of water to wash the tube wall;
PLACE the digestion tube in a ventilation cabinet; ADD 10 mL of sulfuric acid
and 0.5 g of mixed catalyst; INSERT the pear-shaped glass funnel; HEAT it for
1 h in the digestion furnace at 340 °C; PAY attention to avoid drying it; COOL it
down; RINSE the funnel and digestion tube wall.
3.1.4.4 Treatment of sample containing nitrate nitrogen and amide
nitrogen
WEIGH the sample of total nitrogen content of about 100 mg and nitrate
nitrogen content of less than 25 mg (accurate to...