Some standard content:
HG/T2767—1996
The indicators of superior and first-class products in this standard are equivalent to the specifications of sodium dihydrogen phosphate in the Japanese Industrial Standard JIS K1437:1956 (1988) "Sodium Phosphate (Sodium Orthophosphate)".
The main technical differences between this standard and the Japanese Industrial Standard are as follows: The products are divided into three grades according to the actual situation in my country. 1
2 The three indicators of sulfate, chloride and heavy metal required by users are added. 3 The main content indicators in the Japanese Industrial Standard are expressed in two ways: sodium dihydrogen phosphate dihydrate and phosphorus pentoxide. This standard uses sodium dihydrogen phosphate dihydrate to express the main content, and its superior product indicator parameters are better than those of the Japanese Industrial Standard. 4 The main content, water-insoluble matter content, sulfate content and heavy metal content are determined by the methods specified in the Chinese national standard GB/T1908-1980 "Food Additive Sodium Dihydrogen Phosphate". To make the test methods of the same product with different uses unified 5. The iron content, chloride content and arsenic content are determined by the methods specified in the general method standards of my country. This standard is proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of Tianjin Chemical Research Institute of the Ministry of Chemical Industry. Drafting units of this standard: Tianjin Chemical Research Institute of the Ministry of Chemical Industry, Taihu Dye Chemical Factory in Yixing, Jiangsu Province. The main drafters of this standard: Ding Kexin, Yao Jinjuan and Kong Xiangwei. 605
1 Scope
Chemical Industry Standards of the People's Republic of China
Industrial Sodium Dihydrogen Phosphate
HG/T2767—1996
This standard specifies the requirements, sampling, test methods, marking, packaging, transportation and storage of industrial sodium dihydrogen phosphate. This standard applies to industrial sodium dihydrogen phosphate produced by neutralization, crystallization and separation of industrial phosphoric acid and sodium hydroxide (or sodium carbonate). This product is mainly used for boiler water treatment, electroplating buffer, dye auxiliary, pigment precipitant, detergent, mica sheet bonding, baking powder manufacturing, etc.
Molecular formula: 2NaH2PO,·2H,0
Relative molecular mass: 156.01 (according to the 1991 international relative atomic mass) 2 Reference 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. GB191—1990 Pictorial symbols for packaging, storage and transportation
GB/T601--1988 Preparation of standard solutions for titration analysis (volume analysis) of chemical reagents GB/T602—1988 Preparation of standard solutions for determination of impurities in chemical reagents (negIS()6353-1:1982) GB/T603—1988 Preparation of preparations and products used in test methods for chemical reagents (negISO6353-1:1982) GB/T610.1—1988 General method for determination of arsenic in chemical reagents (arsenic spot method) GB/T1250—1989 Method for expressing and determining limit values GB 1908—1980
Food additive Sodium dihydrogen phosphate
GB/T3049—1986 General method for determination of iron content in chemical products-Phenanthroline spectrophotometric method (neqISO) 6685:1982)
GB/T3050—1982 General method for determination of chloride content in inorganic chemical products-Potentiometric titration method (neqISO62271982)
GB/T 6678-1986
GB/T 6682—1992
GB/T 8946--1988
3 Requirements
3.1 Appearance: white crystals.
General rules for sampling of chemical products
Specifications and test methods for water used in analytical laboratories (eqvISO3696:1987) Plastic woven bags
3.2 Industrial sodium dihydrogen phosphate shall meet the requirements of Table 1. Approved by the Ministry of Chemical Industry of the People's Republic of China on January 24, 1996 606
Implementation on January 1, 1997
Main content (as NaH,PO,·2H,O)
Water insoluble matter content
Iron (Fe) content
Arsenic (As) content
Alkalinity (as Naz ())
Sulfate (as S)) content
Chloride (as CI) content
Heavy metal (as Pb) content
4 Sampling
4.1 Each batch of products shall not exceed 30t.
HG/T 2767—1996
Requirements in Table 1
Superior products
18. 8 ~~20. 0
18.8~21. 0
Qualified products
4.2 Determine the number of sampling units in accordance with the provisions of 6.6 of GB/T6678. When sampling, insert the sampler obliquely from the top of the packaging bag to 3/4 of the depth of the material layer to take a sample. After mixing the collected samples, reduce them to no less than 500g according to the quartering method, and pack them into two clean and dry wide-door bottles with stoppers and seal them. Paste labels on the bottles, indicating the manufacturer name, product name, grade, batch number, sampling date and name of the sampler. One bottle is used as a laboratory sample, and the other bottle is kept for three months for reference. 4.3 If one of the test results does not meet the requirements of this standard, re-sampling should be carried out from twice the amount of packaging. If even one of the test results does not meet the requirements of this standard, the entire batch of products will be unqualified. 5 Test methods
5.1 All eight index items specified in this standard are type test items, of which the main content, water-insoluble content, iron content, alkalinity, sulfate content, and chloride content are routine test items and should be tested batch by batch. Under normal production conditions, type tests should be carried out at least once every three months.
5.2 The rounded value comparison method specified in 5.2 of GB/T1250 is used to determine whether the test results meet the standards. 5.3 The reagents and water used in this standard, unless otherwise specified, refer to analytical pure reagents and grade 3 water specified in GB/T6682. Unless otherwise specified, the standard titration solutions, impurity standard solutions, preparations and products used in the test shall be prepared in accordance with the provisions of GB/T601, GB/T602 and GB/T603.
5.4 Determination of main content
According to Chapter 10 of GB1908.
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.2%. 5.5 Determination of water-insoluble matter content
According to Chapter 14 of GB1908.
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.02%. 5.6 Determination of iron content
5.6.1 Summary of method
According to Chapter 2 of GB/T3049.
5.6.2 Reagents and materials
According to Chapter 3 of GB/T3049.
5.6.3 Instruments and equipment
According to Chapter 4 of GB/T3049.
5.6.4 Analysis steps
5.6.4.1 Drawing of working curve
HG/T 2767-1996
According to 5.3 of GB/T3049, use a 3cm absorption cell and the corresponding iron standard solution to draw the working curve. 5.6.4.2 Preparation of test solution
Weigh about 1.5g of sample (accurate to 0.01g), dissolve it in water, transfer it to a 100mL volumetric flask, dilute it to the mark with water, and shake it well. 5.6.4.3 Determination
Use a pipette to transfer 5 mL of the test solution and water (blank test solution) respectively, and place them in 100 mL beakers respectively. The following operations shall be in accordance with the provisions of 5.4 of GB/T3049, starting from "add water to 60 mL if necessary" to "measure the absorbance of the test solution and the reagent blank solution". 5.6.5 Expression of analysis results
The iron (Fe) content (X,) expressed as mass percentage is calculated according to formula (1): Xi
m-m2
m×100
0. 002 (ml -- m2)
Where: m1\—-The mass of iron found on the working curve based on the measured absorbance of the test solution, μg; m—The mass of iron found on the working curve based on the measured absorbance of the blank test solution, ug; m—The mass of the sample, g.
5.6.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.005%. 5.7 Determination of arsenic content
5.7.1 Summary of the method
According to Chapter 3 of GB/T610.1.
5.7.2 Reagents and materials
According to GB/T610.1 Chapter 4 and.
Arsenic standard solution: 1mL solution contains 1μgAs. (1)
Use a pipette to transfer 1mL of the arsenic standard solution prepared according to GB/T 602 into a 100mL volumetric flask, dilute to the mark with water, and shake well. The solution is prepared before use.
5.7.3 Instruments and equipment
According to Chapter 5 of GB/T610.1.
5.7.4 Analysis steps
Weigh 0.100g of the sample (accurate to 0.001g) and place it in a wide-mouth bottle. The following operations are measured according to the method specified in Chapter 6 of GB/T610.1.
Preparation of arsenic standard color spots: Use a pipette to transfer 5mL of the arsenic standard solution into a wide-mouth bottle and treat it in the same way as the sample. 5.8 Determination of alkalinity
5.8.1 Summary of the method
The test solution is acidic and is titrated with a standard sodium hydroxide solution. The alkalinity is calculated by the consumption of the standard sodium hydroxide solution.
5.8.2 Reagents and materials
5.8.2.1 Sodium chloride;
5.8.2.2 Standard sodium hydroxide solution: c(NaOH) about 0.5 mol/L; 5.8.2.3 Phenol indicator solution: 10 g/L.
5.8.3 Analysis steps
HG/T 2767—1996
Weigh about 2 g of the sample (accurate to 0.0002 g), place it in a 250 ml conical flask, add 50 ml of water to dissolve, and add about 5 g of sodium chloride. Keep the solution at (5-15)℃, add 2 drops of phenolphthalein indicator solution, and titrate with sodium hydroxide standard titration solution until the solution turns pink. Perform a blank test at the same time.
5.8.4 Expression of analysis results
The alkalinity (in Naz0) (X) expressed as mass percentage is calculated according to formula (2): Xx = (VV.): cX0. 030 99
9×100
Wherein: V——-the volume of sodium hydroxide standard titration solution consumed in titration, ml; V-the volume of sodium hydroxide standard titration solution consumed in blank titration. mL.; c-the actual concentration of sodium hydroxide standard titration solution, mol/L; m--the mass of the sample, g;
(2))
0.03099.-the mass of sodium oxide in grams equivalent to 1.00mL of sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L).
5.8.5 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.1%. 5.9 Determination of sulfate content
5.9.1 Method summary
In a slightly acidic medium, sulfate ions are precipitated with barium chloride and turbidity is compared with a standard suspension of barium sulfate. 5.9.2 Reagents and materials
5.9.2.1 Hydrochloric acid solution: 1+5;
5.9.2.2 Barium chloride solution: 100g/L;
5.9.2.3 Sulfate standard solution: 1mL solution contains 0.1mgSO4.5.9.3 Analysis steps
Weigh 0.200g of sample (accurate to 0.001g), place in a 50mL colorimetric tube, add 20mL water to dissolve, add 1mL hydrochloric acid solution, 2ml barium chloride solution. Add water to the scale, shake the hook, place in a (40～50)℃ water bath, compare after 10min, and its turbidity shall not be deeper than that of the standard turbidity solution.
The standard turbidity solution is 6.0mL (superior product) and 10.0mI (first-class product) of sulfate standard solution, placed in a 50mL colorimetric tube, and treated in the same way as the sample.
5.10 Determination of chloride content
5.10.1 Summary of the method
According to Chapter 2 of GB/T3050.
5.10.2 Reagents and materials
According to Chapter 4 of GB/T3050.
5.10.3 Instruments and equipment
According to Chapter 3 of GB/T3050.
5.10.4 Analysis steps
Weigh about 10g of the sample (accurate to 0.01g), dissolve it in water and transfer it to a 100mL volumetric flask, dilute it with water to the scale, and shake it well. Use a pipette to transfer 2ml of the test solution and place it in a 50ml beaker. Add 1 drop of bromophenol blue indicator solution, adjust the test solution to yellow with nitric acid solution, add ethanol so that the volume ratio of ethanol to the test solution is 3:1, and the total volume is not more than 40mL. Titrate with silver nitrate standard solution Lc (AgNO) = 0.01mol/L>. The following operations are in accordance with 4.7.3 of GB/T3050, starting from "putting in the electromagnetic stirrer", but do not add 4mL of silver nitrate standard solution again. Perform a blank test at the same time.
5.10.5 Expression of analysis results
According to Chapter 5 of GB/T3050.
5.10.6 Allowable difference
HG/T 2767-1996
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.01%. 5.11 Determination of heavy metal content
5.11.1 Summary of the method
Under weakly acidic conditions, the heavy metal ions in the sample react with hydrogen sulfide to generate brown-black color, which is compared with the standard colorimetric solution. 5.11.2 Reagents and materials
According to Chapter 15 of GB1908.
5.11.3 Analysis steps
Weigh 0.50g of sample (accurate to 0.01g), place in a 50mL colorimetric tube, add 20mL of water to dissolve, add 1 drop of phenolphthalein indicator solution, and adjust to light red with ammonia water. Add 0.5.mL of acetic acid solution, 10mL of saturated hydrogen sulfide water, dilute to scale with water, shake well, and place in a dark place for 10 minutes. Its color should not be darker than the standard colorimetric solution. The standard colorimetric solution is 2.5mL of lead standard solution (0.01mg/nl), which is treated in the same way as the sample. 6 Marking, packaging, transportation, storage
6.1. The packaging of industrial sodium dihydrogen phosphate should be firmly and clearly marked, including the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, and the number of this standard, as well as the "heat-afraid" mark and "wet-afraid" mark specified in GB191. 6.2 Each batch of industrial sodium dihydrogen phosphate shipped out of the factory should be accompanied by a quality certificate. The content includes the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, proof that the product quality complies with this standard, and the number of this standard. 6.3 Industrial sodium dihydrogen phosphate is double-packed. The inner packaging is a polyethylene plastic film bag with a thickness of (0.03~0.05) mm, and the outer packaging is a plastic woven bag. Its performance and inspection methods should comply with G The provisions of Type A and Type B in B/T8946. The net weight of each bag of this product is 25kg and 50kg.
6.4 The inner bag of the double-layer packaging of industrial sodium dihydrogen phosphate is tied manually with vinyl rope or other ropes of equivalent quality, or sealed with other equivalent methods; the outer bag is folded at a distance of not less than 30mm from the edge of the bag, and the mouth is sewn with vinyl thread or other thread of equivalent quality at a distance of not less than 15mm from the edge of the bag. The stitch length is 7mm~12mm, the stitches are neat and the stitch length is uniform. There is no leakage or skipping of seams. 6.5 Industrial sodium dihydrogen phosphate should be covered during transportation to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6.6 Industrial sodium dihydrogen phosphate should be stored in a cool and dry place to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6103 Analysis steps
HG/T 2767—1996
Weigh about 2g of sample (accurate to 0.0002g), place in a 250ml conical flask, add 50ml of water to dissolve, add about 5g of sodium chloride. Keep the solution at (5-15)℃, add 2 drops of phenolphthalein indicator solution, and titrate with sodium hydroxide standard titration solution until the solution turns pink. At the same time, perform a blank test.
5.8.4 Expression of analysis results
The alkalinity (in Naz0) (X) expressed as mass percentage is calculated according to formula (2): Xx = (VV.): cX0. 030 99
9×100
Wherein: V——-the volume of sodium hydroxide standard titration solution consumed in titration, ml; V-the volume of sodium hydroxide standard titration solution consumed in blank titration. mL.; c-the actual concentration of sodium hydroxide standard titration solution, mol/L; m--the mass of the sample, g;
(2))
0.03099.-the mass of sodium oxide in grams equivalent to 1.00mL of sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L).
5.8.5 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.1%. 5.9 Determination of sulfate content
5.9.1 Method summary
In a slightly acidic medium, sulfate ions are precipitated with barium chloride and turbidity is compared with a standard suspension of barium sulfate. 5.9.2 Reagents and materials
5.9.2.1 Hydrochloric acid solution: 1+5;
5.9.2.2 Barium chloride solution: 100g/L;
5.9.2.3 Sulfate standard solution: 1mL solution contains 0.1mgSO4.5.9.3 Analysis steps
Weigh 0.200g of sample (accurate to 0.001g), place in a 50mL colorimetric tube, add 20mL water to dissolve, add 1mL hydrochloric acid solution, 2ml barium chloride solution. Add water to the scale, shake the hook, place in a (40～50)℃ water bath, compare after 10min, and its turbidity shall not be deeper than that of the standard turbidity solution.
The standard turbidity solution is 6.0mL (superior product) and 10.0mI (first-class product) of sulfate standard solution, placed in a 50mL colorimetric tube, and treated in the same way as the sample.
5.10 Determination of chloride content
5.10.1 Summary of the method
According to Chapter 2 of GB/T3050.
5.10.2 Reagents and materials
According to Chapter 4 of GB/T3050.
5.10.3 Instruments and equipment
According to Chapter 3 of GB/T3050.
5.10.4 Analysis steps
Weigh about 10g of the sample (accurate to 0.01g), dissolve it in water and transfer it to a 100mL volumetric flask, dilute it with water to the scale, and shake it well. Use a pipette to transfer 2ml of the test solution and place it in a 50ml beaker. Add 1 drop of bromophenol blue indicator solution, adjust the test solution to yellow with nitric acid solution, add ethanol so that the volume ratio of ethanol to the test solution is 3:1, and the total volume is not more than 40mL. Titrate with silver nitrate standard solution Lc (AgNO) = 0.01mol/L>. The following operations are in accordance with 4.7.3 of GB/T3050, starting from "putting in the electromagnetic stirrer", but do not add 4mL of silver nitrate standard solution again. Perform a blank test at the same time.
5.10.5 Expression of analysis results
According to Chapter 5 of GB/T3050.
5.10.6 Allowable difference
HG/T 2767-1996
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.01%. 5.11 Determination of heavy metal content
5.11.1 Summary of the method
Under weakly acidic conditions, the heavy metal ions in the sample react with hydrogen sulfide to generate brown-black color, which is compared with the standard colorimetric solution. 5.11.2 Reagents and materials
According to Chapter 15 of GB1908.
5.11.3 Analysis steps
Weigh 0.50g of sample (accurate to 0.01g), place in a 50mL colorimetric tube, add 20mL of water to dissolve, add 1 drop of phenolphthalein indicator solution, and adjust to light red with ammonia water. Add 0.5.mL of acetic acid solution, 10mL of saturated hydrogen sulfide water, dilute to scale with water, shake well, and place in a dark place for 10 minutes. Its color should not be darker than the standard colorimetric solution. The standard colorimetric solution is 2.5mL of lead standard solution (0.01mg/nl), which is treated in the same way as the sample. 6 Marking, packaging, transportation, storage
6.1. The packaging of industrial sodium dihydrogen phosphate should be firmly and clearly marked, including the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, and the number of this standard, as well as the "heat-afraid" mark and "wet-afraid" mark specified in GB191. 6.2 Each batch of industrial sodium dihydrogen phosphate shipped out of the factory should be accompanied by a quality certificate. The content includes the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, proof that the product quality complies with this standard, and the number of this standard. 6.3 Industrial sodium dihydrogen phosphate is double-packed. The inner packaging is a polyethylene plastic film bag with a thickness of (0.03~0.05) mm, and the outer packaging is a plastic woven bag. Its performance and inspection methods should comply with G The provisions of Type A and Type B in B/T8946. The net weight of each bag of this product is 25kg and 50kg.
6.4 The inner bag of the double-layer packaging of industrial sodium dihydrogen phosphate is tied manually with vinyl rope or other ropes of equivalent quality, or sealed with other equivalent methods; the outer bag is folded at a distance of not less than 30mm from the edge of the bag, and the mouth is sewn with vinyl thread or other thread of equivalent quality at a distance of not less than 15mm from the edge of the bag. The stitch length is 7mm~12mm, the stitches are neat and the stitch length is uniform. There is no leakage or skipping of seams. 6.5 Industrial sodium dihydrogen phosphate should be covered during transportation to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6.6 Industrial sodium dihydrogen phosphate should be stored in a cool and dry place to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6103 Analysis steps
HG/T 2767—1996bzxZ.net
Weigh about 2g of sample (accurate to 0.0002g), place in a 250ml conical flask, add 50ml of water to dissolve, add about 5g of sodium chloride. Keep the solution at (5-15)℃, add 2 drops of phenolphthalein indicator solution, and titrate with sodium hydroxide standard titration solution until the solution turns pink. At the same time, perform a blank test.
5.8.4 Expression of analysis results
The alkalinity (in Naz0) (X) expressed as mass percentage is calculated according to formula (2): Xx = (VV.): cX0. 030 99
9×100
Wherein: V——-the volume of sodium hydroxide standard titration solution consumed in titration, ml; V-the volume of sodium hydroxide standard titration solution consumed in blank titration. mL.; c-the actual concentration of sodium hydroxide standard titration solution, mol/L; m--the mass of the sample, g;
(2))
0.03099.-the mass of sodium oxide in grams equivalent to 1.00mL of sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L).
5.8.5 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.1%. 5.9 Determination of sulfate content
5.9.1 Method summary
In a slightly acidic medium, sulfate ions are precipitated with barium chloride and turbidity is compared with a standard suspension of barium sulfate. 5.9.2 Reagents and materials
5.9.2.1 Hydrochloric acid solution: 1+5;
5.9.2.2 Barium chloride solution: 100g/L;
5.9.2.3 Sulfate standard solution: 1mL solution contains 0.1mgSO4.5.9.3 Analysis steps
Weigh 0.200g of sample (accurate to 0.001g), place in a 50mL colorimetric tube, add 20mL water to dissolve, add 1mL hydrochloric acid solution, 2ml barium chloride solution. Add water to the scale, shake the hook, place in a (40～50)℃ water bath, compare after 10min, and its turbidity shall not be deeper than that of the standard turbidity solution.
The standard turbidity solution is 6.0mL (superior product) and 10.0mI (first-class product) of sulfate standard solution, placed in a 50mL colorimetric tube, and treated in the same way as the sample.
5.10 Determination of chloride content
5.10.1 Summary of the method
According to Chapter 2 of GB/T3050.
5.10.2 Reagents and materials
According to Chapter 4 of GB/T3050.
5.10.3 Instruments and equipment
According to Chapter 3 of GB/T3050.
5.10.4 Analysis steps
Weigh about 10g of the sample (accurate to 0.01g), dissolve it in water and transfer it to a 100mL volumetric flask, dilute it with water to the scale, and shake it well. Use a pipette to transfer 2ml of the test solution and place it in a 50ml beaker. Add 1 drop of bromophenol blue indicator solution, adjust the test solution to yellow with nitric acid solution, add ethanol so that the volume ratio of ethanol to the test solution is 3:1, and the total volume is not more than 40mL. Titrate with silver nitrate standard solution Lc (AgNO) = 0.01mol/L>. The following operations are in accordance with 4.7.3 of GB/T3050, starting from "putting in the electromagnetic stirrer", but do not add 4mL of silver nitrate standard solution again. Perform a blank test at the same time.
5.10.5 Expression of analysis results
According to Chapter 5 of GB/T3050.
5.10.6 Allowable difference
HG/T 2767-1996
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.01%. 5.11 Determination of heavy metal content
5.11.1 Summary of the method
Under weakly acidic conditions, the heavy metal ions in the sample react with hydrogen sulfide to generate brown-black color, which is compared with the standard colorimetric solution. 5.11.2 Reagents and materials
According to Chapter 15 of GB1908.
5.11.3 Analysis steps
Weigh 0.50g of sample (accurate to 0.01g), place in a 50mL colorimetric tube, add 20mL of water to dissolve, add 1 drop of phenolphthalein indicator solution, and adjust to light red with ammonia water. Add 0.5.mL of acetic acid solution, 10mL of saturated hydrogen sulfide water, dilute to scale with water, shake well, and place in a dark place for 10 minutes. Its color should not be darker than the standard colorimetric solution. The standard colorimetric solution is 2.5mL of lead standard solution (0.01mg/nl), which is treated in the same way as the sample. 6 Marking, packaging, transportation, storage
6.1. The packaging of industrial sodium dihydrogen phosphate should be firmly and clearly marked, including the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, and the number of this standard, as well as the "heat-afraid" mark and "wet-afraid" mark specified in GB191. 6.2 Each batch of industrial sodium dihydrogen phosphate shipped out of the factory should be accompanied by a quality certificate. The content includes the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, proof that the product quality complies with this standard, and the number of this standard. 6.3 Industrial sodium dihydrogen phosphate is double-packed. The inner packaging is a polyethylene plastic film bag with a thickness of (0.03~0.05) mm, and the outer packaging is a plastic woven bag. Its performance and inspection methods should comply with G The provisions of Type A and Type B in B/T8946. The net weight of each bag of this product is 25kg and 50kg.
6.4 The inner bag of the double-layer packaging of industrial sodium dihydrogen phosphate is tied manually with vinyl rope or other ropes of equivalent quality, or sealed with other equivalent methods; the outer bag is folded at a distance of not less than 30mm from the edge of the bag, and the mouth is sewn with vinyl thread or other thread of equivalent quality at a distance of not less than 15mm from the edge of the bag. The stitch length is 7mm~12mm, the stitches are neat and the stitch length is uniform. There is no leakage or skipping of seams. 6.5 Industrial sodium dihydrogen phosphate should be covered during transportation to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6.6 Industrial sodium dihydrogen phosphate should be stored in a cool and dry place to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6104 Analysis steps
Weigh about 10g of sample (accurate to 0.01g), dissolve it in water and transfer it to a 100mL volumetric flask, dilute it to the mark with water and shake it well. Use a pipette to transfer 2mL of test solution to a 50mL beaker, add 1 drop of bromophenol blue indicator solution, adjust the test solution to yellow with nitric acid solution, add ethanol so that the volume ratio of ethanol to test solution is 3:1, and the total volume is not more than 40mL. Titrate with silver nitrate standard titration solution Lc (AgNO) = 0.01mol/L>, and the following operations shall be carried out according to 4.7.3 of GB/T3050 starting from "putting in the electromagnetic stirrer", but do not add 4mL of silver nitrate standard titration solution again. Perform a blank test at the same time.
5.10.5 Expression of analysis results
According to Chapter 5 of GB/T3050.
5.10.6 Allowable difference
HG/T 2767-1996
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.01%. 5.11 Determination of heavy metal content
5.11.1 Method summary
Under weak acidic conditions, the heavy metal ions in the sample react with hydrogen sulfide to produce brown-black, which is compared with the standard colorimetric solution. 5.11.2 Reagents and materials
According to Chapter 15 of GB1908.
5.11.3 Analysis steps
Weigh 0.50g of sample (accurate to 0.01g), place it in a 50mL colorimetric tube, add 20mL of water to dissolve, add 1 drop of phenolphthalein indicator solution, and adjust to light red with ammonia water. Add 0.5 mL of acetic acid solution and 10 mL of saturated hydrogen sulfide water, dilute to the scale with water, shake well, and place in a dark place for 10 minutes. The color should not be darker than the standard colorimetric solution. The standard colorimetric solution is 2.5 mL of lead standard solution (0.01 mg/nl), which is treated in the same way as the test sample. 6 Marking, packaging, transportation, storage
6.1. The packaging of industrial sodium dihydrogen phosphate should be firmly and clearly marked, including the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, and the number of this standard, as well as the "heat-afraid" mark and "wet-afraid" mark specified in GB191. 6.2 Each batch of industrial sodium dihydrogen phosphate shipped out of the factory should be accompanied by a quality certificate. The content includes the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, proof that the product quality complies with this standard, and the number of this standard. 6.3 Industrial sodium dihydrogen phosphate is double-packed. The inner packaging is a polyethylene plastic film bag with a thickness of (0.03~0.05) mm, and the outer packaging is a plastic woven bag. Its performance and inspection methods should comply with G The provisions of Type A and Type B in B/T8946. The net weight of each bag of this product is 25kg and 50kg.
6.4 The inner bag of the double-layer packaging of industrial sodium dihydrogen phosphate is tied manually with vinyl rope or other ropes of equivalent quality, or sealed with other equivalent methods; the outer bag is folded at a distance of not less than 30mm from the edge of the bag, and the mouth is sewn with vinyl thread or other thread of equivalent quality at a distance of not less than 15mm from the edge of the bag. The stitch length is 7mm~12mm, the stitches are neat and the stitch length is uniform. There is no leakage or skipping of seams. 6.5 Industrial sodium dihydrogen phosphate should be covered during transportation to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6.6 Industrial sodium dihydrogen phosphate should be stored in a cool and dry place to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6104 Analysis steps
Weigh about 10g of sample (accurate to 0.01g), dissolve it in water and transfer it to a 100mL volumetric flask, dilute it to the mark with water and shake it well. Use a pipette to transfer 2mL of test solution to a 50mL beaker, add 1 drop of bromophenol blue indicator solution, adjust the test solution to yellow with nitric acid solution, add ethanol so that the volume ratio of ethanol to test solution is 3:1, and the total volume is not more than 40mL. Titrate with silver nitrate standard titration solution Lc (AgNO) = 0.01mol/L>, and the following operations shall be carried out according to 4.7.3 of GB/T3050 starting from "putting in the electromagnetic stirrer", but do not add 4mL of silver nitrate standard titration solution again. Perform a blank test at the same time.
5.10.5 Expression of analysis results
According to Chapter 5 of GB/T3050.
5.10.6 Allowable difference
HG/T 2767-1996
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference of the parallel determination results shall not exceed 0.01%. 5.11 Determination of heavy metal content
5.11.1 Method summary
Under weak acidic conditions, the heavy metal ions in the sample react with hydrogen sulfide to produce brown-black, which is compared with the standard colorimetric solution. 5.11.2 Reagents and materials
According to Chapter 15 of GB1908.
5.11.3 Analysis steps
Weigh 0.50g of sample (accurate to 0.01g), place it in a 50mL colorimetric tube, add 20mL of water to dissolve, add 1 drop of phenolphthalein indicator solution, and adjust to light red with ammonia water. Add 0.5 mL of acetic acid solution and 10 mL of saturated hydrogen sulfide water, dilute to the scale with water, shake well, and place in a dark place for 10 minutes. The color should not be darker than the standard colorimetric solution. The standard colorimetric solution is 2.5 mL of lead standard solution (0.01 mg/nl), which is treated in the same way as the test sample. 6 Marking, packaging, transportation, storage
6.1. The packaging of industrial sodium dihydrogen phosphate should be firmly and clearly marked, including the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, and the number of this standard, as well as the "heat-afraid" mark and "wet-afraid" mark specified in GB191. 6.2 Each batch of industrial sodium dihydrogen phosphate shipped out of the factory should be accompanied by a quality certificate. The content includes the manufacturer's name, address, product name, trademark, grade, net weight, batch number or production date, proof that the product quality complies with this standard, and the number of this standard. 6.3 Industrial sodium dihydrogen phosphate is double-packed. The inner packaging is a polyethylene plastic film bag with a thickness of (0.03~0.05) mm, and the outer packaging is a plastic woven bag. Its performance and inspection methods should comply with G The provisions of Type A and Type B in B/T8946. The net weight of each bag of this product is 25kg and 50kg.
6.4 The inner bag of the double-layer packaging of industrial sodium dihydrogen phosphate is tied manually with vinyl rope or other ropes of equivalent quality, or sealed with other equivalent methods; the outer bag is folded at a distance of not less than 30mm from the edge of the bag, and the mouth is sewn with vinyl thread or other thread of equivalent quality at a distance of not less than 15mm from the edge of the bag. The stitch length is 7mm~12mm, the stitches are neat and the stitch length is uniform. There is no leakage or skipping of seams. 6.5 Industrial sodium dihydrogen phosphate should be covered during transportation to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 6.6 Industrial sodium dihydrogen phosphate should be stored in a cool and dry place to prevent rain and moisture. Prevent high temperature and exposure. It shall not be mixed with alkali. 610
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