GB/T 3595-2000 Determination of ammoniacal nitrogen content in fertilizers - Titration after distillation
Some standard content:
GB/T 3595—2000
This standard is equivalent to ISO5314:1981 "Determination of ammonia nitrogen content in fertilizers - Titration after distillation". This standard makes slight editorial changes to ISO5314:1981 in accordance with the format of my country's standard: Chapter 2 References and Chapter 8 Test Report in ISO5314:1981 are deleted, and the "Foreword" and Chapter 2 "Citation Standards" are added. Technical differences between this standard and ISO5314:1981: a. Added the standard "Foreword" before the "ISO Foreword". b. The provisions of Chapter 1 "Scope" can also be applied to corresponding industrial products. c. Added Chapter 2 "Reference Standards".
d. Chapter 4 "Test Methods" stipulates the preparation of reagents, water and solutions used. When the specifications and preparation methods are not specified, they should comply with the provisions of HG/T2843.
e. In 4.1 Reagents, the indicator uses a methyl red-methylene blue mixed indicator liquid, and the methyl red indicator liquid is deleted. f. In 4.2.1 Distillation Apparatus, the condenser is changed from a 7-bulb Arif condenser to a straight tube condenser: Receiver (conical flask) Change to double-ball absorption bottle.
g. This standard changes 7.2 "Precision" in ISO5314:1981 to 4.4.2 "Allowable Difference". h. 4.4.2 "Allowable Difference" of this standard stipulates that the absolute difference of parallel determinations shall not exceed 0.06%; while the absolute difference of parallel determinations in 7.2 "Precision" in ISO5314:1981 shall not exceed 0.03%. The differences between this standard and GB/T3595-1983 "Determination of Ammonia Nitrogen Content in Fertilizers - Titration after Distillation" are as follows: a. Modified the "Foreword" of the standard.
b. Added "ISO" after the "Foreword" of the standard. Foreword". c. Added Chapter 2 "Cited Standards". d. Chapter 4 "Test Methods" specifies the preparation of reagents, water and solutions used. When the specifications and preparation methods are not specified, they should comply with the provisions of HG/T2843.
e. In 4.1 Reagents, the indicator uses a methyl red-methylene blue mixed indicator solution, and the methyl red indicator solution is deleted. f. 4.1\Distillation Apparatus" in GB/T3595-1983 is deleted, and it is stipulated that the distillation apparatus of ISO3330:1975 can also be used. g. In 4.2.1 Distillation Apparatus, the condenser is changed from a 7-bulb Arrienne condenser to a straight tube condenser; the receiver (conical flask) is changed to a double-connected ball absorption flask.
h. Deleted "Appendix A" of the original standard. This standard replaces GB/T3595-1983 from the date of implementation. This standard is proposed by the State Administration of Petroleum and Chemical Industry. This standard is under the jurisdiction of the National Technical Committee for Standardization of Fertilizers and Soil Conditioners. This standard was drafted by: Shanghai Research Institute of Chemical Industry. This standard was drafted by: Zhu Tao.
This standard was first issued in 1983.
GB/T3595—2000
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of international standard institutes (ISO member bodies). ISO technical committees are responsible for the formulation of international standards. A member body can organize the formulation of standards on behalf of the technical committee. International organizations, governments, and non-governmental organizations that have a cooperative relationship with ISO can also participate.
The draft international standard adopted by the technical committee must be agreed by the member body before it can be confirmed as an international standard by the ISO committee. This standard was formulated by Technical Committee ISO/TC134 Fertilizers and Soil Conditioners and was issued to all member bodies in March 1978. The following member countries voted in favor:
Australia, Brazil, Canada, former Czechoslovakia, Egypt, France, Germany FR, Hungary, India, Iran, Ireland, Israel, Italy, Kenya, Mexico, Netherlands, New Zealand, Norway, Philippines, Poland, Portugal, Romania, South Africa, Spain, Thailand, Turkey, United Kingdom, former Soviet Union, Venezuela, Yugoslavia. No member voted against.
1 Scope
National Standard of the People's Republic of China
Determination of ammoniacal nitrogen content in fertilizers
Titration after distillation
Fertilizers--Determination of ammoniacal nitrogen content-Titrimetric method after distillation This standard specifies the method for determining the nitrogen content in fertilizers by titration after distillation. GB/T 3595--2000
eqv ISO 3514:1981
Replaces GB/T3595---1983
This standard is applicable only when the sample does not contain urea or its derivatives, cyanamides and organic nitrogen compounds, and can also be applied to corresponding industrial products.
2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. HG/T2843-1997 Commonly used standard titration solutions, standard solutions, reagent solutions and indicator solutions for chemical analysis of fertilizer products 3 Method summary
Ammonia is distilled from an alkaline solution, absorbed with an excess sulfuric acid standard solution, and the excess sulfuric acid is titrated with a sodium hydroxide standard titration solution using a methyl red-methylene blue mixed indicator solution as an indicator. 4 Test methods
The preparation of reagents, water and solutions used in this standard shall comply with the provisions of HG/T2843 when the specifications and preparation methods are not specified. 4.1 ReagentsWww.bzxZ.net
4.1.1 Ammonium sulfate: high-grade pure, dried to constant weight at 105℃. 4.1.2 Hydrochloric acid: 1+1 solution.
4.1.3 Sodium hydroxide: 400g/L solution.
Sulfuric acid standard titration solution: c(1/2H,S0,)=0.2mol/L. 4.1.4
4.1.5 Sodium hydroxide standard titration solution: c(NaH)0.2mol/L. 4.1.6 Methyl red-methylene blue mixed indicator solution. 4.1.7 Wide range pH test paper.
4.1.8 Vacuum silicone grease.
4.2 Instruments
General laboratory instruments and
4.2.1 Distillation instruments
It is best to use complete instruments with standard ground joints or any instruments that can ensure quantitative distillation and absorption. The various components of the distillation instrument are connected with rubber stoppers and rubber tubes, or spherical ground glass joints. To ensure the sealing of the system, the spherical glass joints should be clamped with spring clips. Approved by the State Administration of Quality and Technical Supervision on July 31, 2000 and implemented on March 1, 2001.
GB/T 3595--2000
The distillation apparatus recommended for use in this standard is shown in Figure 1, and includes the following parts: A distillation flask, 1000mL, with a No. 29 internal standard ground joint; B splash-proof ball tube, the end connected to the distillation flask has a No. 29 external standard ground joint, and the end connected to the condenser has a No. 19 external standard ground joint;
C dropping funnel, capacity of 50ml;
D condenser, effective length of about 400mm, inlet with a No. 19 internal standard ground joint, outlet with a No. 29 external standard ground joint; absorption bottle, 500mL, the bottle mouth has a No. 29 internal standard ground joint, and the bottle side is connected with a double ball. E
1000mL
A-distillation flask; B-splash-proof bulb; C-dropping funnel, D-condenser; E-absorption flask Figure Distillation apparatus diagram
4.2.2 Iron stand and spring clamp for fixing the device. 4.2.3 Explosion-proof zeolite or explosion-proof tube (consisting of a 100mm×5mm glass rod connected to a 25mm polyethylene tube). 4.2.4 Mechanical oscillator.
4.3 Analysis steps
4.3.1 Sample
Weigh about 10g of sample, accurate to 0.001g, and transfer it into a 500mL volumetric flask. 4.3.2 Preparation of test solution
4.3.2.1 Water-soluble products
Add about 400 ml of 20°C water to the sample (4.3.1) and shake the volumetric flask continuously for 30 min using a mechanical shaker (4.2.4). 4.3.2.2 Products containing water-insoluble substances that may retain ammonia 108
GB/T3595—2000
Add 50 ml of water and 20 mL of hydrochloric acid solution (4.1.2) to the sample (4.3.1), mix the contents in the volumetric flask, let it stand until the release of carbon dioxide stops, add about 400 mL of water, and shake the volumetric flask continuously for 30 min using a mechanical shaker. Note: The above procedure is to extract all nitrogen in the nitrogen state, and the sample does not need to be completely dissolved. 4.3.3 Determination
4.3.3.1 Distillation
Dilute with water to the scale of the measuring flask and mix well. Dry filter into a beaker with medium-speed quantitative filter paper, discard the first 50mL of filtrate, and then use a pipette to transfer a portion of the filtrate into the distillation flask (4.2.1A). The filtrate should contain 25mg~100mg of ammonia nitrogen, preferably 75mg~100mg. Add about 350ml of water and a few explosion-proof zeolites or explosion-proof tubes (4.2.3) to the distillation flask. Use a single-line pipette to transfer 50.0mL of sulfuric acid standard titration solution (4.1.4) into the absorption bottle (4.2.1E), add water so that the solution can seal the connection between the double ball and the bottle, and add 4~5 drops of indicator solution (4.1.6). Apply silicone grease to the instrument interface, install the instrument according to the distillation device diagram, and ensure that all parts of the instrument are sealed. Inject 15mL of sodium hydroxide solution (4.1.3) into the distillation flask through the dropping funnel (4.2.1C). If 20mL of hydrochloric acid solution (4.1.2) has been added when dissolving the sample (see 4.3.2.2), 25mL of sodium hydroxide solution (4.1.3) should be added at this time. Note that 2mL of solution should be left in the dropping funnel and diluted with water to 15mL~20mL. Heat and distill until the amount of distillate collected in the absorption flask reaches 250mL. Move the absorption flask slightly away and use a wide range pH test paper (4.1.?) to test whether the subsequent distillate is neutral to ensure that all ammonia is completely evaporated. Stop heating, open the dropping funnel, remove the splash-proof bulb (4.2.1B), rinse the condenser (4.2.1D) with water, and collect the washing liquid in the absorption flask, and remove the absorption flask. 4.3.3.2 Titration
Mix the solution in the absorption bottle and back-titrate the excess sulfuric acid standard titration solution with sodium hydroxide standard titration solution (4.1.5) until the indicator turns gray-green.
4.3.4 Blank test
At the same time as the determination, except that no sample is added, the same analytical steps, reagents and dosages are carried out in parallel. 4.3.5 Verification test
Use freshly prepared ammonium sulfate containing 100 mg nitrogen (4.1.1) to regularly check the efficiency of the distillation apparatus and the accuracy of the determination method. The verification test should adopt the same conditions as the determination of the sample and blank test, and use the same indicator. 4.4 Expression of analysis results
4.4.1 Calculation
Nitrogen content, expressed as mass percentage X of nitrogen (N), is calculated according to formula (1): x(%) V-c×0. 014 01 × 100.m
Wherein:
c—concentration of sodium hydroxide standard titration solution, mol/L; V.—volume of sodium hydroxide standard titration solution consumed by the test sample, ml(1)
V2——volume of sodium hydroxide standard titration solution consumed by the blank test, ml; 0.01401——mass of nitrogen in grams equivalent to 1.00mL sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L];
m-mass of the test sample, g.
Take the arithmetic mean of the parallel determination results as the determination result. 4.4.2 Allowable Difference
The absolute difference between parallel determinations shall not exceed 0.06%; the absolute difference between determinations in different laboratories shall not exceed 0.08%. 109
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