GB/T 3260.6-2000 Chemical analysis method for tin - Determination of arsenic content
Some standard content:
GB/T3260.6 2000
This standard is a revision of GB/T3260.6·1982 "Chemical analysis method of tin - determination of arsenic by indirect photometric method using ferro-o-phenoline". This standard complies with: bZxz.net
GB/T1.1·1993
Guidelines for standardization work Unit 1: Drafting and expression of standards Part 1: Basic provisions for standard writing
GB/T1.4 1988 Guidelines for standardization work Provisions for the writing of chemical analysis methods GB/T1467-1978 General principles and general provisions for chemical analysis methods of metallurgical products GB/T7729 1987 General principles for spectrophotometry of chemical analysis of metallurgical products GB/T17433—1998 Basic terminology for chemical analysis of metallurgical products This standard replaces GB/T3260.6-1982 from the date of implementation. This standard was proposed by the National Nonferrous Metals Industry Week. This standard is under the jurisdiction of China Nonferrous Metals Industry Standard Metrology and Quality Research Institute. This standard was drafted by Yunnan Tin Company and Liuzhou Huaxi Group Co., Ltd. This standard was drafted by Yunnan Tin Co., Ltd. Smelting Branch. The main drafters of this standard method are Yin Gang, Yang Jun and Li Zhihong. 76
1 Scope
National Standard of the People's Republic of China
Chemical analysis method of tinDetermination of arsenic contentThis standard specifies the method for determination of arsenic content in Guangxi tin: This standard is applicable to the determination of arsenic content in tin. Determination range: 0.00020%~0.12%2 Summary of the method
GB/T 3260. 6-2000
Replaces GB/T 3260.6-7G82
The sample is decomposed with sulfuric acid and hydrogen peroxide. In sulfuric acid medium, zinc particles are used to reduce the molybdenum to hydrogen gas and separate it from the matrix. The gas is absorbed by iodine solution. Under sulfuric acid acidity of c (1/2HSO,) = 0.7 ~ 0.9 mol / L, polyvinyl alcohol is used as a stabilizer. Arsenic 1 heteropoly acid and porphyrin green form a green ion complex, and its absorbance is measured at a wavelength of 635nm on a spectrophotometer. 3 Reagents
3.1 Arsenic-free zinc particles (3 ~ 7mm).
3.2 Sulfuric acid (pl. 84 g / mL).
3.3 Hydrogen peroxide (30%).
3.4 Sulfuric acid (1 + 1).
3.5 Sulfuric acid 15.0% (V / V).
3.6 Hydrochloric acid (1 + 1).
3.7 Hydrochloric acid (1 + 99).
3.8. Stannous chloride solution (400 g/L): Weigh 40 g of stannous chloride (SnCl2·2H.O) in a 200 ml beaker, add about 80 ml of hydrochloric acid (3.6), cover with a beaker, slightly heat until the solution is completely clear, cool to room temperature, then dilute to 100 mL with hydrochloric acid (3.6), and mix with 3.9 tartaric acid solution (300 g/L).
3.10 Iodine absorption solution (2g/1.): weigh 2g iodine and 4g potassium iodide in a measuring cup, add a little water to dissolve, dilute with water to 11, mix 3.11 Sodium sulfite solution (100g/L): weigh 1g anhydrous sodium sulfite and dissolve in 10mL water, transfer to a dropper bottle (as a preparation) 3.12 Ammonium molybdate solution (15g/L): accurately weigh 7.50g ammonium molybdate [(N)MoO2·4H20] in 400ml beaker, add water to slightly heat to dissolve, cool and dilute with water to 500ml, transfer to a plastic bottle, mix. 3.13 Ammonium molybdate sulfuric acid mixture: accurately measure equal volumes of ammonium molybdate solution (3.12) and sulfuric acid (3.5) in a plastic bottle, mix well (prepare daily).
3.14 Polyvinyl alcohol (PVA-124, degree of polymerization 2400~~2500) solution (10g/L): weigh 1g polyvinyl alcohol in a beaker: 100mL water, heat to dissolve, cool and dilute to 100ml with water, mix well. Use a funnel with cotton to dry filter before use, 3.15 Malachite green (biochrome BS, molecular formula: Ca2Cl2 molecular weight: 364.90) solution (1.5g/L): weigh 0.30))g malachite green and dissolve in 80mL ethanol (1+1), dilute to 200ml with water, mix well. Use a funnel and cotton to filter. 3.16 Standard stock solution: weigh 0.1320g of arsenic trioxide (standard reagent) previously dried at 105°C to constant weight in a 10ml beaker. Add 10mL of sodium hydroxide solution (200g/L) to dissolve, add 5mL of sulfuric acid (3.4), 0.5ml of hydrogen peroxide, heat and boil for 10min, cool, transfer to a 1000mL volumetric flask with water and dilute to scale, mix. This solution contains 100ug 3.17 Arsenic standard solution: transfer 20ml of arsenic standard stock solution, place in a 500mL volumetric flask, dilute to scale with water and mix. This solution contains 4μg of arsenic in 1ml.
3.18 Arsenic standard solution: Pipette 10mL of arsenic standard storage solution into a 500mL volumetric flask, dilute to the mark with water and mix well. This solution contains 2μg of arsenic per ml.
4 Equipment and instruments
Arsenic hydrogen generation and absorption device (see Figure 1). 120~130
1 Arsenic hydrogen gas generation bottle (150mL conical flask) 2-Rubber stopper; 3-Gas guide tube; 4-Latex tube: 5Absorption tube (25mL colorimetric tube) Figure 1 Arsenic hydrogen generation and absorption device
5 Analysis steps
5.1 Test materials
Weigh the sample according to Table 1, accurate to 0.00018. Table 1
Monument content, %
0. 000 20~ 0. 002 4
>0. 002 4- 0. 004 0
≥0.0040~0.0060
≥0. 006 0~ 0. 012
0. 012 ~ 0. 024
0. 024~ 0. 040
0. 040~- 0. 060
-0. 060-~0. 12
Sample·
The measurement was carried out twice independently and the average value was taken. 5.2 Blank test
Blank test with the sample
5.3 Determination
Prepare the test solution volume, mL
Take the test solution volume, ml.
5.3.1 Place the sample (5.1) in a 150mL conical flask (when the arsenic content is ≤0.012%) or a 100mL beaker +r (when the arsenic content is 78
GB/T3260.6-2000
>0.012%). Add 2.0mL hydrogen peroxide and 7.0mL sulfuric acid (3.2), mix well, decompose slightly on an electric furnace, add moisture to drive away large bubbles, continue strong heat evaporation for 4 to 6 minutes to make sulfuric acid emit thick white smoke, remove and cool. Add 25ml. water, mix well, and cool. Note: When the arsenic content is greater than 0.012%, use hydrochloric acid (3.7) to transfer the test solution in the beaker into a 50ml volumetric flask, cool and dilute to zero, mix, take 5ml of the test solution and put it into a 150ml conical flask, add 10ml of sulfuric acid (3.4), add 15ml of water, mix well, and start from 5.3.2. 5.3.2 adds 2ml of stannous chloride solution, mix well, add 5ml of tartaric acid solution, mix well, add 7g of arsenic-free zinc granules, and immediately connect the absorption device. The outlet end of the airway should be close to the bottom of the absorption tube. First add 10ml of iodine absorption liquid into the absorption tube to absorb the escaped hydrogen peroxide gas. After 25 minutes of reaction, remove the airway and purge the tube wall with a small amount of water. Note: If the antimony content in the test solution is greater than 400ug, 4ml of stannous chloride solution should be added to suppress the interference of antimony. 5.3.3 Add 4 drops of sodium sulfite solution to the absorption tube, shake to reduce the iodine solution to colorless, add 8.0mL of molybdic acid-sulfuric acid mixture, 1mL of polyvinyl alcohol solution, mix well, add 2.0mL of malachite green solution, dilute to scale with water, mix well, and immediately heat in a water bath at 60°C + 10°C for 8 minutes. Take out and cool with cold water.
5.3.4 Pipette part of the solution, use 1cm or 2cm absorption according to the arsenic content, and measure its absorbance at a wavelength of 635nm on a spectrophotometer with the blank test solution accompanying the sample as a reference. Find the corresponding amount from the working curve. 5.41. Draw the curve
5.4.1 Pipette 0, 1.0, 1.5, 2.0, 2.5, 3.0ml of arsenic standard solution (3.17 or 3.18). Place them in two groups of 150ml generation bottles respectively. Add 10mL of sulfuric acid (3.4). Dilute with water to 30mL and mix well. The following is carried out according to 5.3.2~5.3.4. 5.4.2 Under the same conditions as the test sample, measure the absorbance of the standard solution with the reagent blank as the reference. Draw the working curve with the rolling degree as the horizontal axis and the absorbance as the vertical axis.
Note: Each bottle of zinc particles needs to calibrate its own curve. 6 Expression of analysis results
Calculate the percentage of arsenic according to formula (1):
As(%) = ml -V. X 10-s
Where: m—-the amount of arsenic found from the working curve, ug; Va—-the total volume of the test solution, mL;
V,-the volume of the test solution taken.mI.
moThe mass of the test sample·g.
The result is expressed to three decimal places. If the content is less than 0.010%, it shall be expressed to four decimal places; if it is less than 0.0010%, it shall be expressed to five decimal places.
7 Allowable Difference
The difference between the analysis results of laboratories shall not be greater than the allowable difference listed in Table 2. Table 2
Arsenic content
0. 000 20- 0. 000 50
0. 000 50~0. 001 0
2 0. 001 0~ 0. 003 0
>0. 003 0~0. 006 0
Allowable difference
C. 000 30
Arsenic content
0. 006 0-- 0. 010
>0. 010~0. 030
20.030~0.060
>0.060~0.12
Allowable difference
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