Some standard content:
Chemical Industry Standard of the People's Republic of China
1 Subject Content and Scope of Application
HG/T 2326-92
This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of industrial zinc sulfate. This standard applies to zinc sulfate monohydrate and zinc sulfate heptahydrate produced by reacting zinc-containing raw materials with sulfuric acid. This product is mainly used in chemical industry, chemical fiber, mineral processing, metallurgy, electroplating and circulating cooling water treatment. Molecular formula: Zinc sulfate monohydrate: ZnSO.·H,O Zinc sulfate heptahydrate: ZnSO·7H,O
Relative molecular mass: Zinc sulfate monohydrate: 179.47 (according to the international relative atomic mass in 1989) Zinc sulfate heptahydrate: 287.56 (according to the international relative atomic mass in 1989) 2 Reference standards
GB 191
GB 601
GB 1250
GB3049
GB3050
GB3051
GB 6678
GB 6682
Packaging, storage and transportation pictorial symbols
Preparation of standard solutions for titration analysis (volumetric analysis) of chemical reagents Preparation of standard solutions for determination of impurities in chemical reagents Preparation of preparations and products used in test methods for chemical reagents Methods of indicating and determining limit values General method for determination of iron content in chemical products Spectrophotometric method with o-phenanthroline General method for determination of chloride content in inorganic chemical products Potentiometric titration General method for determination of chloride content in inorganic chemical products Mercuriometric method General rules for sampling of chemical products
Specifications for water for laboratories
GB 8946
3 Product classification
Plastic woven bag
Industrial zinc sulfate is divided into two categories: Class I and Class II. Class 3.11 is zinc sulfate monohydrate;
3.2 Class II is zinc sulfate heptahydrate.
4 Technical requirements
4.1 Appearance: white or slightly yellow crystals or powder. Industrial zinc sulfate should meet the requirements of the following table:
Approved by the Ministry of Chemical Industry of the People's Republic of China on June 1, 1992418
Implementation on September 1, 1992
(Calculated as Zn)
Main content (calculated as ZnS)H,O)
(Calculated as ZnSO, -7H,0 (in terms of)
Insoluble matter content
pH value (50g/L solution)
Chloride (in terms of CI) content
Lead (Ph) content
Iron (Fe) content
Manganese (Mn) content
Cadmium (Cd) content
Copper (Cu) content\
Note: 1) Inspection is required by the user.
5Test method
Superior product
HG/T2326—92
Qualified product
Superior product
%(m/m)
Qualified product
The reagents and water used in this standard, unless otherwise specified, refer to analytically pure reagents and grade 3 water specified in GB6682. Standard solutions, impurity standard solutions, preparations and products required in the test, unless otherwise specified, shall be prepared in accordance with the provisions of GB601, GB602 and GB603.
5.1 Determination of main content
5.1.1 Summary of method
Ammonium fluoride and potassium iodide are added to zinc sulfate solution to eliminate the interference of impurities such as iron. At a pH of about 5.5, dimethyl methacrylate is used as an indicator and titrated with disodium ethylenediaminetetraacetic acid standard titration solution. 5.1.2 Reagents and materials
5.1.2.1 Potassium iodide (GB1272).
5.1.2.2 Ammonium fluoride (GB1276) solution: 200g/L. 5.1.2.3 Sulfuric acid (GB625) solution: 1+1 solution. 5.1.2.4 Acetic acid (GB676)-sodium acetate (GB693) buffer solution: pH=5.5, weigh 200g sodium acetate, dissolve in water, add 10mL glacial acetic acid, dilute to 1000mL.
5.1.2.5 Disodium ethylenediaminetetraacetate (GB1401) standard titration solution: c (EDTA) is about 0.05mol/L. 5.1.2.5.1 Preparation
Weigh 20g disodium ethylenediaminetetraacetate, heat and dissolve in 1000mL water, cool, and shake to hook. 5.1.2.5.2 Calibration
Weigh 1g of reference zinc oxide burned to constant weight at 800℃, accurate to 0.0002g; moisten with a small amount of water, add 1+1 hydrochloric acid solution until completely dissolved, transfer to a 250mL volumetric flask, dilute to scale, and shake well. 419
HG/T 2326- 92
Use a pipette to transfer 25mL of the above solution, place it in a 250mL conical flask, add 2 drops of 1g/L p-nitrophenol indicator, adjust the solution to yellow with 1+1 ammonia water, and adjust the solution to colorless with 1+1 hydrochloric acid solution. Add 15mL of acetic acid-sodium acetate buffer solution and 3 drops of 2g/L xylenol orange indicator, and titrate with disodium ethylenediaminetetraacetic acid standard titration solution (5.1.2.5) until the solution changes from red to bright yellow. Perform a blank test at the same time.
5.1.2.5.3 Calculation
The concentration of the standard titration solution of disodium ethylenediaminetetraacetate is calculated according to formula (1): m×250
c=(V,=V)× 0.081 38
0.813 8(V,-V,)
wherein℃
5. 1. 2. 6
actual concentration of the standard titration solution of disodium ethylenediaminetetraacetate, mol/L; mass of zinc oxide, g;
volume of the disodium ethylenediaminetetraacetate solution to be standardized consumed in the titration, mL; volume of the disodium ethylenediaminetetraacetate solution to be standardized consumed in the blank test, mL; (1)
mass of zinc oxide equivalent to 1.00mL of the standard titration solution of disodium ethylenediaminetetraacetate [c(EDTA)-1.000mol/L), expressed in grams.
Xylenol orange indicator solution: 2g/L.
5.1.3 Analysis steps
Weigh an appropriate amount of sample (about 3g for Class I and about 5g for Class II), accurately to 0.0002g, place in a 250mL beaker, add 10 drops of sulfuric acid solution (5.1.2.3), transfer to a 250mL volumetric flask, dilute to scale with water, and shake well. Use a pipette to transfer 25mL of the test solution to a 250mL conical flask, add 50mL of water, 10mL of ammonium fluoride solution (5.1.2.2), and 0.5g of potassium iodide (5.1.2.1), mix well, add 15mL of acetic acid-sodium acetate buffer solution (5.1.2.4), 3 drops of xylenol orange indicator solution, and titrate with disodium ethylenediaminetetraacetic acid standard titration solution (5.1.2.5) until the solution changes from red to bright yellow. Perform a blank test at the same time.
5.1.4 Expression of analytical results
5.1.4.1 The zinc sulfate content (in terms of Zn) expressed as a mass percentage, X, is calculated according to formula (2): Xx 0. 065 39:-V) × 100
65. 39c. (V-V.)
Wherein: c—actual concentration of disodium ethylenediaminetetraacetic acid standard titration solution, mol/L; volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed in the titration, mL; V. Volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed in the blank test, mL, m
mass of the sample, g;
· (2)
mass of zinc equivalent to 1.00mL disodium ethylenediaminetetraacetic acid standard titration solution c (EDTA) = 1.000mol/L), expressed in grams.
5.1.4.2 The content X of monohydrate zinc sulfate (ZnSO·H,O) expressed as mass percentage is calculated according to formula (3): _ 0.1795c. (VV) × 100
m×250
_179.5c: (V - V.)
Wu Zhong: c
actual concentration of disodium ethylenediaminetetraacetic acid standard titration solution, mol/L; · (3)
HG/T2326--92
the volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed in a titration, mL; V. - Volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed in blank test, mL; m
- Mass of sample, g;
0.1795 --- Mass of zinc sulfate monohydrate expressed in grams equivalent to 1.00 mL disodium ethylenediaminetetraacetic acid standard titration solution c (EDTA) = 1.000 mol/1.).
5.1.4.3 The content X of zinc sulfate heptahydrate (ZnSO·7H,O) expressed in mass percentage is calculated according to formula (4): Xx = 0.287 6c - V) × 100
m×250
287. 6c · (V- V.)
Wu Zhong: c
actual concentration of disodium ethylenediaminetetraacetic acid standard titration solution, mol/L; -volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed in titration, mL; V
V. ——volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed in blank test, mL; m
-mass of sample, g;
（4）
0.2876——mass of zinc sulfate heptahydrate equivalent to 1.00mL disodium ethylenediaminetetraacetic acid standard titration solution [c(EDTA)=1.000mol/L], expressed in grams.
5.1.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result; the absolute difference of the parallel determination results: X, not more than 0.15%, X2, X, not more than 0.4%.
5. 2 Determination of insoluble content
5.2.1 Method summary
Dissolve the sample with water and a small amount of sulfuric acid, filter and wash the insoluble matter, and dry to constant weight. 5.2.2 Reagents and materials
5.2.2.1 Sulfuric acid (GB625) solution: 1+1 solution; 5.2.2.2 Barium chloride (GB652) solution: 100g/L. 5.2.3 Instruments and equipment
5.2.3.1 Crucible filter: The pore size of the filter plate is 5~~15μm. 5.2.4 Analysis steps
Weigh about 50g of sample, accurate to 0.01g, place in a 500mL beaker, add 300mL warm water and 2mL sulfuric acid solution to dissolve the sample, filter with a crucible filter that has been pre-conditioned at 105-110°C, wash with warm water until there is no sulfate ion (check with barium chloride solution), transfer to an oven and dry at 105-110°C to constant weight. 5.2.5 Expression of analysis results
The insoluble content X4 expressed as a mass percentage is calculated according to formula (5): m×100
Where: m
Mass of insoluble matter after drying,;
Mass of sample, g.
5.2.6 Allowable difference
·(5)
The arithmetic mean of the parallel determination results shall be taken as the determination result; the absolute difference of the parallel determination results: the superior and standard products shall not exceed 0.005%, and the qualified products shall not exceed 0.01%.
5.3 Determination of pH value
5.3.1 Summary of method
After dissolving the sample, measure the pH value with an acidometer. 421
5.3.2 Instruments and equipment
HG/T2326---92
5.3.2.1 Acidometer: The graduation value is 0.02 pH unit and is equipped with a glass measuring electrode and a saturated calomel reference electrode. 5.3.3 Analysis steps
Weigh about 5g of sample, accurate to 0.01g, place in a 150mL beaker, add 100mL of water to dissolve, and measure with an acidometer. 5.3.4 Allowable difference
Take the arithmetic mean of the parallel determination results as the determination result; the absolute difference of the parallel determination results shall not exceed 0.2pH, unit. 5.4 Determination of fluoride content
5.4.1 Multiplication method
5.4.1.1 Summary of the method
Same as Article 2 of GB3051.
5.4.1.2 Reagents and materials
5.4.1.2.1 Nitric acid (GB626) solution: 1+1.5; 5.4.1.2.2 Sodium hydroxide (GB620) solution: 40g/L. 5.4.1.2.3 Mercuric nitrate standard titration solution: c[Hg(NO.)2H,O) is about 0.05mol/L, prepare and calibrate 0.05mol/L standard titration solution according to Article 4.9 of GB3051;
5.4.1.2.4 Bromophenol blue (HG3-1244) indicator solution: 1g/L; 5.4.1.2.5 Diphenylazocarbohydrazide indicator solution: 5g/L. 5.4.1.3 Instruments and equipment
5.4.1.3.1 Microburette: the graduation value is 0.01 or 0.02mL. 5.4.1.4 Analysis steps
Weigh about 5g of the sample, accurate to 0.01g, place it in a 250mL conical flask, and add 100mL of water to dissolve. Add 2 to 3 drops of bromophenol blue indicator solution (5.4.1.2.4), add nitric acid (5.4.1.2.1) or sodium hydroxide solution (5.4.1.2.2) until the test solution turns blue, then add nitric acid solution (5.4.1.2.1) until it turns from blue to yellow, and add 1mL in excess. Add 1mL of diphenylazocarbonylhydrazide indicator solution (5.4.1.2.5), and titrate with mercuric nitrate standard titration solution (5.4.1.2.3) until the test solution turns from yellow to purple-red. Perform a blank test at the same time.
Retain the mercury-containing waste liquid after titration and treat it according to the provisions of Appendix D of GB3051. 5.4.1.5 Expression of analytical results
The chloride content (in terms of Cl) expressed as mass percentage is calculated according to formula (6): X, -V) *× 0.035 45 ×100
3.545c(V - Vo)
Wherein: C is the actual concentration of the standard mercuric nitrate titration solution, mol/L; V is the volume of the standard mercuric nitrate titration solution consumed in the titration, mL; V is the volume of the standard mercuric nitrate titration solution consumed in the blank test, mL; m is the mass of the sample, g;
0.03545 is the mass of chlorine expressed with 1.00 mL of the standard mercuric nitrate titration solution/c.
5.4.1.6 Allowable difference
. (6)
Hg(NO,)2H,O]=1.000mol/L), the arithmetic mean of the parallel determination results is taken as the determination result in grams. The absolute difference of the parallel determination results shall not exceed 0.02%. 5.4.2 Potentiometric titration
5.4.2.1 Method summary
Same as Article 2 of GB3050.
5.4.2.2 Reagents and materials
5.4.2.2.1 Nitric acid (GB626) solution: 1+1. HG/T 2326-- 92
5.4.2.2.2 Sodium hydroxide (GB629) solution: 40g/L. 5.4.2.2.3 Sodium fluoride (GB1253) standard solution: c (NaCI) = 0.05 mol/L. Weigh 2.9225 g of standard sodium chloride that has been dried to constant weight at 500-600°C, accurate to 0.0002 g, place in a beaker, add water to dissolve, transfer to a 1000 mL volumetric flask, dilute with water to the scale, and shake well. 5.4.2.2.4 Silver nitrate (GB670) standard titration solution: c (AgNO3) about 0.05 mol/L. Weigh about 8.75 g of silver nitrate, dissolve in 1000 mL of water, shake well, and store the solution in a brown bottle. Use a pipette to transfer 5mL of sodium chloride standard solution into a 100mL beaker, add an electromagnetic stirrer, place the beaker on an electromagnetic stirrer, start the stirrer, add 2 drops of bromophenol blue indicator solution (5.4.2.2.5), add nitric acid or sodium hydroxide solution until the test solution turns yellow, insert the measuring electrode (5.4.2.3.3) and the reference electrode (5.4.2.3.2) into the solution, connect the electrodes to the potentiometer, adjust the zero point of the potentiometer, and record the starting potential value. Titrate with silver nitrate standard titration solution. First add 4.00mL, then add 0.10mL gradually, record the total volume and corresponding potential value E after each addition of silver nitrate standard titration solution, and calculate the continuously increasing potential values △, E and △, E. The maximum value of A, E is the endpoint of the titration. Record another potential value E after the endpoint. The recording format is shown in Appendix C of GB3050. The volume of the silver nitrate standard titration solution consumed by the titration to the endpoint is calculated according to formula (7): .V
VV. +
Wherein: V. - — the volume of the silver nitrate standard titration solution added before the potential increment A,E reaches the maximum value, mL; V, — the volume of the silver nitrate standard titration solution added for the last time before the potential increment △,E reaches the maximum value, mL; 6 — the last positive value of △,E;
B — the sum of the absolute values of the last positive value and the first negative value of △,E (see the example in Appendix C of GB3050 for details). The concentration c of the silver nitrate standard titration solution is calculated according to formula (8): C
Wherein: c. — the concentration of the sodium chloride standard solution, mol/L; c2V
V2-. — the volume of the sodium chloride standard solution removed during titration, mL; V — the volume of the silver nitrate to be calibrated solution consumed by titration, ml. 5.4.2.2.5 Bromophenol blue (HG3-1244) indicator solution: 1 g/L. 5.4.2.3 Instruments and equipment
5.4.2.3.1 Potentiometer: accuracy is 2mV/grid, range is 500~+500mV;.(7)
·(8)
5.4.2.3.2 Reference electrode: double liquid junction saturated calomel electrode, filled with saturated potassium chloride solution. During titration, the outer sleeve is filled with saturated potassium nitrate solution and connected to the calomel electrode;
5.4.2.3.3 Measuring electrode: silver electrode or silver sulfide coated electrode (preparation method see Appendix A of GB3050); 5.4.2.3.4 Microburette: graduation value is 0.01 or 0.02mL. 5.4.2.4 Analysis steps
Weigh an appropriate amount of sample (2g for superior products, 1g for first-class products), accurate to 0.01g, place in a 100mL beaker, add 40mL of water to dissolve, put in an electromagnetic stirrer, place the beaker on an electromagnetic stirrer, start the stirrer, add 2 drops of bromophenol blue indicator solution, and add nitric acid or sodium hydroxide solution until the test solution just turns yellow. The following operations are carried out in accordance with the provisions of 5.4.2.2.4, starting from "inserting the measuring electrode and the reference electrode into the solution" and ending with "recording a potential value E after the end point". However, do not add 4mL of silver nitrate standard titration solution again. Perform a blank test at the same time.
5.4.2.5 Expression of analysis results
Chloride content (in terms of CI) expressed as mass percentage X. Calculate according to formula (9): 423
HG/T 2326-- 92
Vo): c× 0.035 45 × 100
3.545c(V-Vo)
-actual concentration of standard silver nitrate titration solution, mol/L-volume of standard silver nitrate titration solution consumed in titration, mL; volume of standard silver nitrate titration solution consumed in blank test, mL; mass of sample, g;
the mass of chlorine in grams equivalent to 1.00mL standard silver nitrate titration solution [c(AgNO)=1.000mol/L.
5.4.2.6 Allowable difference
Take the arithmetic mean of the parallel determination results as the determination result; the absolute difference of the parallel determination results shall not exceed 0.02%. 5.5 Determination of lead content
5.5.1 Method summary
In dilute nitric acid medium, use air-acetylene flame at the wavelength of 283.3nm of atomic absorption spectrophotometer and adopt standard addition method.
5.5.2 Reagents and materials
5.5.2.1 Nitric acid (GB626) solution: 1+1; 5.5.2.2 Lead standard solution: 1mL solution contains 0.1mg lead. 5.5.3 Instruments and equipment
5.5.3.1 Atomic absorption spectrophotometer;
5.5.3.2 Lead hollow cathode lamp.
5.5.4 Instrument working conditions
5.5.4.1 Wavelength: 283.3nm;
5.5.4.2 Flame: air-acetylene.
5.5.5 Analysis steps
Weigh about 30g of sample, accurate to 0.01g, dissolve in 50mL of water, add 5ml of nitric acid solution, transfer to a 250mL volumetric flask after dissolution, dilute to scale with water, and shake well.
Use a pipette to transfer 25mL of test solution to 5 100mL volumetric flasks, then use a pipette to add 0, 1, 2, 4, and 6mL of lead standard solution, dilute to scale with water, and shake well. According to the provisions of Article 5.5.4, adjust the instrument to the optimal working conditions, adjust to zero with water, and measure the absorbance. Draw a working curve with the mass of lead as the horizontal axis and the corresponding absorbance as the vertical axis. The mass of lead in the test solution is obtained by extending the curve in the opposite direction and the intersection with the horizontal axis.
5.5.6 Expression of analysis results
The lead (Pb) content X expressed as a mass percentage is calculated according to formula (10): mi
m×1 000× 100
Wu Zhong: m -
-the mass of lead in the test solution found from the working curve, mg; -the mass of the sample, g.
5.5.7 Allowable difference
(10)
The arithmetic mean of the parallel determination results is taken as the determination result; the absolute difference of the parallel determination results: the superior product is not more than 0.001%; the inferior product and qualified product is not more than 0.003%.
5.6 Determination of iron content
5.6.1 Summary of the method
Same as Article 2 of GB3049.
5.6.2 Reagents and materials
Same as Article 3 of GB3049 and
HG/T 2326 -- 92
5.6.2.1 Mixed solution of disodium ethylenediaminetetraacetate (GB1401) and triammonium citrate (HG3-516): weigh 100g disodium ethylenediaminetetraacetate and 122g triammonium citrate, and dissolve them in 1000mL water. 5.6.3 Instruments and equipment
5.6.3.1 Spectrophotometer: with an absorption cell with a thickness of 1cm. 5.6.4 Analysis steps
5.6.4.1 Drawing of working curve
See Article 5.3 of GB3049. Use an absorption cell with a thickness of 1cm and the corresponding amount of iron standard solution to draw the working curve. 5.6.4.2 Determination
Weigh about 10g of sample, accurate to 0.01g, dissolve and transfer to a 250mL volumetric flask, add water to the scale, and shake well. Use a pipette to transfer an appropriate amount of test solution (25mL for superior products; 10mL for first-class products and qualified products) to a 100mL volumetric flask, and add an appropriate amount of water to another 100mL volumetric flask as a blank. At the same time, add 2.5mL of ascorbic acid solution and an appropriate amount of ethylenediaminetetraacetic acid disodium-ammonium citrate trihydrate mixed solution (40mL for superior products; 20mL for first-class products and qualified products), adjust the pH to 5.8-6.3 with 2+3 ammonia water (precision pH test paper test), add 5mL of o-phenanthroline solution, dilute with water to the scale, and shake well. After standing for 30 minutes, measure the absorbance with water as a reference. 5.6.5 Expression of analysis results
Iron (Fe) content X expressed as mass percentage. Calculate according to formula (11): Xg =
5×100
m×1000
0.1(mi-m.)
Wherein: m1-the mass of iron found from the working curve according to the measured absorbance of the test solution, mg; m.-the mass of iron found from the working curve according to the measured absorbance of the blank test solution, mg; m-the mass of the sample contained in the transferred test solution, g. 5.6.6 Allowable difference
(11)
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results is: not more than 0.001% for superior products; not more than 0.005% for inferior products and qualified products.
5.7 Determination of manganese content
5.7.1 Spectrophotometric method
5.7.1.1 Summary of the method
In a strong acidic medium in the presence of phosphoric acid, potassium periodate is used to oxidize the divalent manganese ions in the test solution into purple-red permanganate ions. At the maximum absorption wavelength (525nm), the absorbance is measured by a spectrophotometer. 5.7.1.2 Reagents and materials
5.7.1.2.1 Phosphoric acid (GB 1282);
5.7.1.2.2 Potassium periodate (HG3--1158); 5.7.1.2.3 Sulfuric acid (GB625);
5.7.1.2.4 Manganese standard solution: 1mL of solution contains 0.1mg manganese (Mn). 5.7.1.3 Instruments and equipment
5.7.1.3.1 Spectrophotometer: with an absorption cell of 1 cm thickness. 5.7.1.4 Analysis steps
5.7.1.4.11. Plotting the curve
HG/T2326-92
Use a pipette to take 0.1, 2.4, 6, 8, 10 ml of manganese standard solution and place them in a 300 ml beaker respectively, add water to about 40 ml, add 2.5 ml of sulfuric acid, 10 ml of phosphoric acid and 0.5 g of potassium periodate respectively, heat and boil until the purple-red color of permanganate appears, and then boil slightly for 5 minutes. After cooling, transfer all of them to a 100 ml volumetric flask respectively, dilute with water to the scale, and shake well. Use a 1 cm absorption cell, measure the absorbance at a wavelength of 525 nm, with water as the reference, and plot the working curve. 5.7.1.4.2 Determination of sample
Weigh about 1g of sample, accurate to 0.01g. Place in a 250mL beaker, add 40mL of water to dissolve, and take another 40mL of water in another beaker as a blank. Heat the test solution and blank test solution to boiling, and filter if necessary. The following operations are as described in 5.7.1.4.1, starting from "add 2.5mL of sulfuric acid..." to "measure absorbance". 5.7.1.5 Expression of analysis results
Content X of manganese (Mn) expressed as mass percentage. Calculated according to formula (12): m - mo
=m×1000
0. 1(mJ - mo)
Wherein: m, the mass of manganese found from the working curve according to the measured absorbance of the test solution, mg; m, the mass of manganese found from the working curve according to the measured absorbance of the blank test solution, mg; m.
The mass of the sample, mg.
5.7.1.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result; the absolute difference of the parallel determination results shall not exceed 0.005%. 5.7.2 Atomic absorption spectrometry (arbitration method) 5.7.2.1 Method summary
-( 12 )
In dilute nitric acid medium, at the wavelength of 279.5nm of the atomic absorption spectrophotometer, use air-acetylene flame and adopt the working curve method to determine.
5.7.2.2 Reagents and materials
5.7.2.2.1 Nitric acid (GB626) solution: 1+1; 5.7.2.2.2 Lanthanum nitrate solution: 50g/L. Weigh 5g of lanthanum nitrate, dissolve it in 10mL of nitric acid solution, and dilute it to 100mL with water; 5.7.2.2.3 Manganese standard solution: 1mL of solution contains 0.1mg manganese (Mn). 5.7.2.3 Instruments and equipment
5.7.2.3.1 Atomic absorption spectrophotometer; 5.7.2.3.2 Manganese hollow cathode lamp.
5.7.2.4 Instrument working conditions
5.7.2.4.1 Wavelength: 279.5nm;
5.7.2.4.2 Flame: air-acetylene.
5.7.2.5 Analysis steps
Weigh about 0.5g of sample, accurate to 0.0002g, and place it in a 200mL beaker. Add 20mL of water and 5mL of nitric acid solution. After dissolving, transfer it to a 100mL volumetric flask, add 5mL of lanthanum nitrate solution, dilute to scale with water, shake well, and use a pipette to transfer 0, 0.5, 1, 2, 3, 5, 7mL of manganese standard solution to a series of 100mL volumetric flasks, respectively, add 5mL of nitric acid solution and 5mL of lanthanum nitrate solution, dilute to scale with water, and shake well. According to the provisions of 5.7.2.4, adjust the instrument to the best working conditions, adjust to zero with water, and measure the absorbance of the test solution and the standard series solution. At the same time, a blank test is performed.
Use the mass of manganese in the standard series solution as the horizontal axis and the corresponding absorbance as the vertical axis to draw a working curve. Editor's note: 1) The original version is "potassium persulfate", which is changed to "potassium periodate" in this version. 126
5.7.2.6 Expression of analysis results
HG/T2326-92
The manganese (Mn) content X1 expressed as a mass percentage. Calculate according to formula (13): mi mg
m×1000
0. 1(mi - mo)
Where: mi
The mass of manganese found from the working curve based on the absorbance of the tested solution, mg; -The mass of manganese found from the working curve based on the measured absorbance of the blank test solution, mg; The mass of the sample, g.
5.7.2.7 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 0.005%. 5.8 Determination of content
5.8.1 Atomic absorption spectrometry (arbitration method) 5.8.1.1 Summary of method
(13)
In dilute nitric acid medium, at the wavelength of 228.8nm of the atomic absorption spectrophotometer, use air-acetylene flame and adopt the standard curve method for determination.
5.8.1.2 Reagents and materials
5.8.1.2.1 Nitric acid (GB626) solution: 1+1; 5.8.1.2.2 Cadmium standard solution: 1mL solution contains 0.1mg cadmium (Cd). 5.8.1.3 Instruments and equipment
5.8.1.3.1 Atomic absorption spectrophotometer; 5.8.1.3.2 Cadmium hollow cathode lamp.
5.8.1.4 Instrument working conditions
5.8.1.4.1 Wavelength: 228.8nm;
5.8.1.4.2 Flame: air-acetylene.
5.8.1.5 Analysis steps
Weigh about 5g of sample, accurate to 0.01g, dissolve in 30mL of water, add 5mL of nitric acid solution. After dissolution, transfer to a 100mL volumetric flask, dilute to scale with water, and shake well.
In a series of 100mL volumetric flasks, use a pipette to transfer 0, 1, 2, 3, 4, 5, 6mL of standard solution, add 5mL of nitric acid solution to each, dilute to scale with water, and shake well. According to the provisions of 5.8.1.4, adjust the instrument to the best working conditions, adjust to zero with water, and measure the absorbance of the test solution and the standard series solution. Perform a blank test at the same time.
Use the mass of cadmium in the standard series solution as the abscissa and the corresponding absorbance as the ordinate to draw a working curve. 5.8.1.6 Expression of analysis results
The cadmium (Cd) content X1 expressed as mass percentage is calculated according to formula (14): Xu =
mi-mo
m × 1 000
0. 1(m, mo)
—The mass of cadmium found from the working curve according to the absorbance of the tested test solution, mg; Where: m,
The mass of cadmium found from the working curve according to the measured absorbance of the blank test solution, mg; ma
The mass of the sample, g.
5.8.1.7 Allowable difference
(14)
The arithmetic mean of the parallel determination results shall be taken as the determination result; the absolute difference of the parallel determination results shall be: not more than 0.001% for superior products; not more than 0.003% for first-class 427
products and qualified products.
5.8.2 Polarographic method
5.8.2.1 Method summary
HG/T 2326—92
In ammoniacal ammonium chloride solution, deoxygenate with sodium sulfite and determine by polarography. 5.8.2.2 Reagents and materials
5.8.2.2.1 Nitric acid (GB626) solution: 1+1; 5.8.2.2.2 Ammonium hydroxide (GB631); 5.8.2.2.3 Sodium nitrite (HG3-1078); 5.8.2.2.4 Ammonium chloride (GB658);
5.8.2.2.5 Animal glue solution: 5g/L
5.8.2.2.6 Cadmium standard solution: 1mL solution contains 0.1mg cadmium (Cd). 5.8.2.3 Instruments and equipment
5.8.2.3.1 Polarograph.
5.8.2.4 Analysis steps
Weigh about 10g of sample, accurate to 0.01g, place in a 250mL beaker, add 30mL water, 5mL nitric acid solution, heat to a slight boil for 5min, add 2g ammonium chloride after cooling, add ammonium hydroxide solution until the generated zinc hydroxide precipitate is completely dissolved and 10mL excess. Transfer to a 100mL volumetric flask, add 4ml. animal glue solution and 1g sodium sulfite, dilute with water to the scale, shake well. Leave for 10min, and measure its wave height with a polarograph.
Standard comparison solution: Use a pipette to transfer 10mL of cadmium standard solution into a 100mL volumetric flask, add 2g ammonium chloride, 20mL ammonium hydroxide, 4mL animal glue solution and 1g sodium sulfite, dilute with water to the scale, shake well. Pour out part of the standard comparison solution and measure it using the same polarographic branch as the sample. Measure its wave height. 5.8.2.5 Expression of analysis results
The cadmium (Cd) content X12 expressed as mass percentage is calculated according to formula (15): h·mo
Xia =h, mX1000 × 100
Wherein: h,-
wave height of test solution, mm; bzxZ.net
wave height of standard reference solution, mm;
mass of cadmium contained in standard reference solution, mg; -mass of sample, g.
5.8.2.6 Allowable difference
(15)
The arithmetic mean of the parallel determination results is taken as the determination result; the absolute difference of the parallel determination results: for superior products, not more than 0.001%; for first-class products and qualified products, not more than 0.003%.
5.9 Determination of copper content
5.9.1 Method summary
In a solution with a pH of 5.7 to 9.2, copper ions react with copper reagent (sodium diethyl dithiocarbamate) to form a yellow colloidal suspension, which is extracted with organic reagents such as ethyl acetate and then subjected to colorimetric determination. 5.9.2 Reagents and materials
5.9.2.1 Nitric acid (GB626) solution: 1+1; 5.9.2.2 Ammonia water (GB631): 1+1 solution; 5.9.2.3 Disodium ethylenetriaminetetraacetic acid (GB1401) solution: 50g/L solution; 5.9.2.4 Potassium sodium tartrate (GB1288) solution: 100g/L; 428
5.9.2.5 Ethyl acetate (HG 3-—1226); HG/T2326—92
5.9.2.6 Sodium diethyldithiocarbamate (copper reagent) (HG3-962) solution: 1g/L; 5.9.2.7 Ammonium chloride (GB658) saturated solution; 5.9.2.8 Copper standard solution: 1mL solution contains 0.01mg copper (Cu). Use a pipette to transfer 10mL of the copper standard solution prepared according to GB602 and dilute to 100ml. Use only on the same day. 5.9.3 Instruments and equipment
5.9.3.1 Spectrophotometer: with an absorption cell of 3 cm thickness. 5.9.4 Analysis steps
5.9.4.1 Drawing of working curve
Use a pipette to transfer 0, 1, 2, 3, 4, and 5 mL of copper standard solution into a 125 mL separatory funnel, add 20 mL of ammonium chloride solution, 2 mL of disodium ethylenediaminetetraacetic acid solution, and 2 mL of potassium sodium tartrate solution, and shake well. Use ammonia water to adjust the pH of the test solution to 8 (pH test paper test). Add 2 mL of copper reagent, accurately add 10.0 mL of ethyl acetate, cover the bottle cap tightly, and shake for 1 minute. After the solution is separated, take the organic layer solution, use a 3 cm absorption cell, and measure the absorbance at a wavelength of 435 nm with water as the reference. Draw a working curve with the mass of copper as the horizontal axis and the corresponding absorbance as the vertical axis. 5.9.4.2 Determination of sample
Weigh about 5g of sample, accurate to 0.01g, place in a 250mL beaker, add 30mL of water and 5mL of nitric acid solution, heat to dissolve. After cooling, transfer to a 100mL volumetric flask, dilute to scale with water, and shake well. Use a pipette to transfer 20mL of test solution into a 125mL separatory funnel, and at the same time take 20mL of water into another separatory funnel as a blank. The following operations are the same as those in 5.9.4.1, starting from "adding 20mL of ammonium chloride solution" to "measuring absorbance". 5.9.5 Expression of analysis results
The copper (Cu) content X13 expressed as mass percentage is calculated according to formula (16): mi-mo
Xis =mx100 × 100
0. 1(m, - m.)
Wherein: m, — the mass of copper found from the working curve based on the measured absorbance of the test solution, mg; - the mass of copper found from the working curve based on the measured absorbance of the blank test solution, mg; mo
m—the mass of the sample in the transferred test solution, g. 5.9.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result; the absolute difference of the parallel determination results shall not exceed 0.0005%. 6 Inspection rules
(16)
6.1 Industrial zinc sulfate shall be inspected by the quality supervision and inspection department of the manufacturer in accordance with the provisions of this standard. The manufacturer shall ensure that all products leaving the factory meet the requirements of this standard.
Each batch of products leaving the factory shall be accompanied by a quality certificate, which shall include: manufacturer name, product name, category, grade, net weight, batch number or production date, proof that the product quality meets this standard and the number of this standard. 6.2 The user has the right to inspect and accept the industrial zinc sulfate received in accordance with the provisions of this standard. 6.3 Each batch of products shall not exceed 60t.
6.4 Determine the number of sampling units in accordance with Article 6.6 of GB6678. When sampling, insert the sampler vertically from the center of the bag to 3/4 of the depth of the material layer to take samples. Mix the collected samples, reduce them to no less than 500g by quartering method, and pack them into two clean, dry wide-mouth bottles with stoppers and seal them. Stick labels on the bottles, indicating the manufacturer name, product name, category, grade, batch number, sampling date and the name of the sampler. One bottle is for inspection and the other bottle is kept for three months for reference.
6.5 If one of the indicators in the test results does not meet the requirements of this standard, samples should be taken from twice the amount of packaging units for re-verification.
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