This standard specifies the method for determining the lead content in copper and copper alloys. This standard is applicable to the determination of lead content in copper and copper alloys, with a determination range of 0.001 5% to 5.00%. GB/T 5121.3-1996 Chemical analysis method for copper and copper alloys Determination of zinc content GB/T5121.3-1996 Standard download decompression password: www.bzxz.net

1 Scope
National Standard of the People's Republic of China
Chemical analysis method for copper and copper alloys
Determination of lead content
Copper and copper alloys—Determination of lead content This standard specifies the method for determination of lead content in copper and copper alloys. This standard is applicable to the determination of lead content in copper and copper alloys, with a determination range of 0.0015% to 5.00%. Reference standards GB/T5121.3-1996 Replaces GB121.3 5122.39 GB 6520.11 GB 8002.4 GB 8002.5 GB 8550.5 GB 8550.10 The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. The versions shown are valid when this standard is published. All standards will be revised. All parties using this standard should explore the possibility of using the latest version of the following standards: GB1.4--88 Standardization Guidelines for the Preparation of Chemical Analysis Methods GB1467--78 General Principles and General Provisions for Chemical Analysis Methods for Metallurgical Products GB7728--87 General Principles for Chemical Analysis of Metallurgical Products Flame Atomic Absorption Spectrometry 3 Method Summary
The sample is dissolved in nitric acid or mixed acid. When the lead content is greater than 0.04%, the atomic absorption determination is carried out directly without separation; when the lead content is not greater than 0.04%, strontium nitrate and hydroxide are used to coprecipitate lead and separate it from the matrix elements such as copper, tin, and nickel. In an acidic medium, use an air acetylene flame to measure the absorbance of lead at a wavelength of 283.3nm on an atomic absorption spectrometer. 4 Reagents
4.1 Ammonium carbonate.
4.2 Sulfuric acid (pl.84g/mL)
4.3 Hydrofluoric acid (ol.13 g/ml.).
Ammonia water (p0.9g/mL).
Nitric acid (1+1).
Hydrochloric acid (1+1).
Hydrochloric acid (1+100).
Sulfuric acid (1+100).
Mixed acid: Add 320ml nitric acid (pl.42g/ml) and 120ml hydrochloric acid (pl.19g/ml.) to 560ml water and mix well. 4.9
Boric acid saturated solution.
Ammonium fluoride solution (200g/L).
Strontium nitrate solution (30g/.).
Iron solution (8g/L): weigh 57.8g ferric nitrate LFc (NO,): ·9HO dissolved in 1000ml. nitric acid (1+100) 4 mix well Washing solution: weigh 10g ammonium carbonate (4.1) dissolved in 500ml water, add 20ml ammonia water (4.4) and mix 5 Lead standard solution: weigh 0.2500g pure lead, put it in a 250ml beaker. Add 10ml. water, 20ml. nitric acid (4.5), cover 4.15
Approved by the State Administration of Technical Supervision in 1996-1104
Implementation in 199704-01
GB/T5121.3.- 1996
Heat the watch glass at low temperature until it is completely dissolved, boil to remove nitrogen oxides, and cool. Transfer to a 1000mL volumetric flask, dilute to the scale with water, and mix. This solution contains 250μg lead per 1ml.
5 Instruments
Original absorption spectrometer with lead hollow cathode lamp. Under the best working conditions of the instrument, any instrument that can meet the following indicators can be used: Sensitivity: In a solution consistent with the matrix of the sample solution, the characteristic concentration of lead should not exceed 0.47μg/ml. Precision: When the absorbance is measured 10 times with the highest concentration standard solution, its standard deviation should not exceed 1.0% of the average absorbance; when the absorbance is measured 10 times with the lowest concentration standard solution (not the "zero" concentration solution), its standard deviation should not exceed 0.5% of the average absorbance of the highest concentration standard solution.
Linearity of working curve: Divide the working curve into five sections according to concentration, and the ratio of the absorbance difference of the highest section to the absorbance difference of the lowest section should not be less than 0.7.
See Appendix A (Suggested Appendix) for instrument working conditions. 6 Analysis steps
6.1 Test sample
Weigh the sample according to Table 1, accurate to 0.0001g. Table 1
Content, %
0. 001 5~0. 005 0
>0. 005 0~0. 010
>0. 010-~0. 040
>0. 040~0. 10
>0. 10~0. 20
>0. 20~0. 40Www.bzxZ.net
0. 40~1.00
1. 00~2. 00
>2. 00~5. 00
Acid content, mL.
Carry out two independent determinations and take the average value. 6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
6.3.1 Sample treatment
6.3.1.1 Copper and processed copper fluoride with lead content not more than 0.04% Amount, mL
Amount of mixed acid, mL
Volume of test solution.ml.
6.3.1.1.1 Place the sample (6.1) in a 400mL beaker, add 50~70ml. nitric acid, and heat at low temperature until it is completely dissolved. Boil to remove nitrogen oxides.
6.3.1.1.2 Add 10mL of iron solution, dilute with water to about 200mL, slowly add nitrogen water under stirring until the solution turns dark blue, add 20ml excess, add 10g of ammonium carbonate, heat the solution to a slight boil for 5min, and place it in a water bath at 70~80℃ for 1h. 210
GB/T5121.3—1996
6.3.1.1.3 Filter the precipitate with filter paper, wash the beaker and filter paper with hot washing liquid until the filter paper is no longer blue, then wash with warm water for 10 times, and discard the filtrate. Wash the precipitate into the original beaker with water, dissolve the remaining precipitate on the filter paper with 10mL hot hydrochloric acid (4.6), wash with hot hydrochloric acid (4.7) until the filter paper is colorless, add the washing liquid into the original beaker, heat and evaporate until the solution is almost dry, cool slightly, add 4mL hydrochloric acid (4.6), heat to dissolve and cool. Transfer to a 25mL volumetric flask, dilute to scale with water, and mix well. 6.3.1.2 Copper alloy with lead content less than 0.04% 6.3.1.2.1 Place the sample (6.1) in a 300mL beaker, add nitric acid and ammonium fluoride solution according to Table 1, cover with a watch glass, and heat at low temperature until the solution is completely dissolved after the violent reaction stops. Boil to remove nitrogen oxides, and dilute with water to a volume of about 100)ml. 6.3.1.2.2 Add 8mL sulfuric acid (4.2), heat the solution to a slight boil, wash the watch glass and the wall of the cup with water, slowly add 8ml strontium nitrate solution while stirring until a precipitate appears, continue stirring for 2 minutes, and let it stand for 1 hour. 6.3.1.2.3 Filter the precipitate with slow filter paper, wash the beaker and precipitate with sulfuric acid (4.8) 3 times each, then wash with water 3 times, and discard the filtrate. Spread out the filter paper, wash the precipitate into the original beaker with water, rinse the filter paper with 30mL nitric acid, and add the washing liquid into the original beaker. Heat the solution to a boil and stir to dissolve the precipitate. The following is carried out according to 6.3.1.1.2 to 6.3.1.1.3. However, add ammonia water until the ferric hydroxide precipitate is completely precipitated and the excess is 20 ml. When filtering, wash the beaker and the precipitate with hot washing liquid 3 times each. 6.3.1.3 Copper alloy with lead content greater than 0.04% 6.3.1.3.1 Place the sample (6.1) in a 150mL beaker, add mixed acid according to Table 1 (for samples with silicon as the main component, add 0.9 ml of hydrofluoric acid) and heat until completely dissolved, boil, and cool. 6.3.1.3.2 Transfer to a volumetric flask according to Table 1, dilute with water to the scale, and mix well (for samples with silicon as the main component, add 30 ml of saturated boric acid solution).
6.3.2 Measurement
Use air-acetylene flame at the atomic absorption spectrometer wavelength of 283.3nm, and at the same time as the standard solution series, adjust with water, measure the absorbance of the test solution, subtract the absorbance of the blank solution accompanying the sample, and find the corresponding lead concentration from the working curve. 6.4 Drawing of working curve
6.4.1 Preparation of standard series
6.4.1.1 Lead content not more than 0.04%: transfer 0, 2.00, 4.00, 6.00, 8.00, 10.00mL of lead standard solution into a 100ml volumetric flask, add 15ml of hydrochloric acid (4.6) and 40mL of iron solution respectively, dilute with water to the scale, and mix. 6.4.1.2 Lead content greater than 0.04%: weigh 6 portions of pure copper equal to the sample, and place them in 150ml.In a beaker, add the mixed acid according to Table 1, heat to dissolve, boil, and cool. Transfer to a 100mL volumetric flask, add 0, 2.00, 4.00, 6.00, 8.00, and 10.00ml of lead standard solution, dilute to scale with water, and mix well. 6.4.2 Draw the working curve
Under the same conditions as the test solution, measure the absorbance of the standard solution and subtract the absorbance of the "zero" concentration solution in the standard solution series.
7 Expression of analysis results
Calculate the percentage of lead according to formula (1):
Pb(%) = V× 10-°
Where: c--lead concentration found from the working curve, ug/mL; V--total volume of test solution, mL;
m.--mass of the test material, g.
The result is expressed to two decimal places. If the lead content is less than 0.10%, it shall be expressed to 3 decimal places; if it is less than 0.010%, it shall be expressed to 4 decimal places.
8 Allowable difference
GB/T5121, 3-1996
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 2 Table 2
1.0015~0.0040
20. 004 0~-0. 010
0.010~0.025
0.0250.060
>0. 060~0. 15
0.15~~0.40
0. 40~1. 00
1. 00~2. 00
>2. 00~~5. 00
GB/T51213--1996
Appendix A
(Suggestive Appendix)
Instrument Working Conditions
The working conditions for determining the amount of lead using the Z-8000 atomic absorption spectrometer are shown in Table A1. Table A1
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