This standard specifies the method for determining the copper content in copper and copper alloys. This standard is applicable to the determination of copper content in copper and copper alloys. The determination range is 50.00% to 99.00%. GB/T 5121.1-1996 Chemical analysis method for copper and copper alloys Determination of copper content GB/T5121.1-1996 Standard download decompression password: www.bzxz.net

GB/T 5121.1~-5121.23--1996
In this series of standards, "Determination of Copper Content" method 2, "Determination of Iron Content" method 1, "Determination of Tin Content" method 2, and "Determination of Manganese Content" method 1 and "Determination of Content" are equivalent to [ISO1553:1976 "Determination of Copper Content in Steel with a Content of Not Less Than 99.90% Pure Copper - Electrolytic Method" ISO1812:1976 "Determination of Iron Content in Copper and Copper Alloys - 1.10 Nitrogen Phenanthrene Spectrophotometric Method" 1S)3111:1973 "Copper Alloys...Determination of Alloying Element Tin - Titration Method" 1S25431973 "Copper and Copper Alloys - Determination of Manganese Content - Potassium Periodate Spectrophotometric Method", 1S ()5960:1984 "Copper Alloys - Determination of Manganese Content - Flame The original absorption spectroscopy method is used as follows: a) "Determination of Copper Content" Method 2: The determination range is greater than 99.90% ~ 99.98%, IS01553: 1976 is not less than 99.9%; b) "Determination of Iron Content" Method 1: The determination range is 0.0015% ~ 0.50%. IS0) 1812: 1976 is not greater than (.1 series (m/m): c) "Determination of Tin Content" Method 2: The determination range is 0.50% ~ 10.00%. IS0) 3111: 1975 is 0.5%13: d) "Determination of Manganese" Method 1: The determination range is 0.030% ~ 2.50%, the precision is determined by selecting t levels according to GB6379 in 1993 and the results of the common test of eight laboratories were obtained. The measurement range of IS02543:1973 is less than 6% (m/m), and there is no provision for precision. The measurement range of ISO2543:1973 is less than 6% (m/m), and there is no provision for precision. The measurement range of ISO2543:1973 is 0.50%~1.50%. The measurement range of ISO5960:1984 is 0.0005%~2.0%. This series of standards changes the unreasonable standard system structure of the original standard that sets the analysis method standard based on the grade of copper and copper alloys, and establishes a scientific standard system structure based on the measurement of light elements. The former includes 9 standards for chemical analysis methods of copper, brass, silicon bronze and silicon brass, tin copper, white, aluminum bronze, chromium bronze, cadmium bronze, and beryllium bronze. A total of 21 elements and 125 analysis methods are measured: the latter includes 23 standards for chemical analysis methods of copper and copper alloys, a total of 24 elements and 33 analysis methods are measured, and its system has been in line with international standards. The scope of application of this series of standards includes the determination of chemical composition content of all 88 grades of copper and copper alloy smelting and processing products and casting products of the same grade specified in GB46682, GB5231--85, GB5232---85, GB523335 and GB523485, among which the determination methods of copper, iron, zinc, aluminum, manganese, tin, nickel, carbon, sulfur, lead, chromium, beryllium, titanium, oxygen, cadmium, phosphorus, silicon, arsenic, antimony and bismuth are revised; the determination method 3 (gravimetric method) of silicon content and the determination method of cobalt content are the corresponding methods in the original GB6520--86 and GB8550-87 standards respectively, which have been revised after editorial modification. Newly confirmed method; the determination method of silver, magnesium and zirconium content is a newly formulated method. The "Determination of Oxygen Content" method in this series of standards (pulse heated gas melting infrared absorption method) is limited to the national conditions that most production units and major users lack oxygen measuring instruments. The original YS/T335-94 (i.e. YB731-70) "Metallographic Examination Method for Oxygen Content of Oxygen-Free Copper for Vacuum Devices" is valid at the same time as the new standard. After the oxygen measuring instruments are widely used, the original oxygen content measurement standard will be abolished. From the date of entry into force of this series of standards, it will replace GB5121--85, GB5122--85, G6520--86, GB800287GB8550-87. At the same time, the original industry standards YS/T316--94 (i.e. YB55-64), YS/T326-94 (i.e. YB59865), YS/T327--94 (i.e. YB599---65), and YS/T328--94 (i.e. YB600--65) are invalidated. In the appendices of this series of standards, except for Appendix A of "Determination of Manganese Content", "Determination of Phosphorus Content", and "Determination of Silicon Content", the appendices A of other element content determination methods are all suggestive appendices. This series of standards was proposed by China Nonferrous Metals Industry Corporation. This series of standards was drafted by Luoyang Copper Processing), Shenyang Nonferrous Metals Processing Plant, and the Standard Design Institute of China Nonferrous Metals Industry Corporation.
The main responsible drafters of this series of standards are: Zhang Delai, Chen Derun, and Qin Yan. The drafting units and drafters of this series of standards are shown in the following table: 193
GB/T 5121.1~5121.23—1996
Sub-standard
Determination of copper content
Determination of phosphorus content
Determination of lead content
Determination of carbon and sulfur content
Determination of nickel content
Determination of bismuth content
Determination of arsenic content
Determination of oxygen content
Determination of iron content
Determination of tin content
Determination of zinc content
Determination of antimony content
Determination of aluminum content
Determination of manganese content
Determination of cobalt content
Determination of chromium content
Determination of beryllium content
Determination of magnesium content
Determination of silver content
Determination of zirconium content
Determination of titanium content
Determination of cadmium content
Determination of silicon content
Drafting unit
Luoyang Copper Processing Factory
Luoyang Copper Processing Factory
Luoyang Copper Processing Factory
Shenyang Nonferrous Metal Processing Factory
Shanghai Copper Tube General Factory
Zhejiang Metallurgical Research Institute
Beijing General Research Institute of Nonferrous Metals
Shenyang Nonferrous Metal Processing Factory
Luoyang Copper Processing Factory
Luoyang Copper Processing Factory
Baiyin Nonferrous Metals Company Northwest Copper Processing Factory Shenyang Nonferrous Metals Processing Factory
Shanghai Copper Tube General Factory
Shenyang Nonferrous Metals Processing Plant
Shenyang Nonferrous Metal Processing Plant
Shenyang Nonferrous Metal Processing Plant
Baiyin Nonferrous Metal Company Northwest Copper Processing Plant Aerospace Corporation 621st Institute
Shenyang Nonferrous Metal Processing Plant
Shenyang Nonferrous Metal Processing Plant
Beijing Research Institute of Mining and Metallurgy
Luoyang Copper Processing Plant
Luoyang Copper Processing Plant
Drafters
Xia Qingzhu, Ji Dehou
Wang Tongyu, Xia Qingzhu
Sun Yujia
Guan Jinguang
Qian Huping
Zhou Jizhan, Kong Shuilong, Jiang Shaojuan
Wang Kegang
Li Sufeng
Zhang Delai
Yang Daixin, Tang Xiaosu
Li Jihe, Ji Chunfang
Wang Jiancheng, Yang Haidong, Yi Shuqing
Xie Jingshan
Chen Derun, Gao Song
Chen Derun
Chen Derun
Yang Luoyuan
Huang Shumao, Jiang Xiuyu
Li Sufeng
Guangyang Haidong, Wang Jiancheng
Zhou Yihua
Yuan Huaibao
Deng Wanmei
Song Shunmao
1 Scope
National Standard of the People's Republic of China
Chemical analysis method of copper and copper alloys
Determination of copper content
Copper and copper alloys-Determination of copper content Part I Method 1 Electrolysis-Atomic Absorption Spectrometry This standard specifies the method for determining the copper content in copper and copper alloys. This standard is applicable to the determination of copper content in copper and copper alloys. The determination range is 50.00% to 99.00%. 2 Referenced standards
GB/T 5121.11996
Replaces G35121.1
GR 5122.1
GB 6520. 12
GB 8002.1
GB 8550. 1
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. GB1.4-88 Guidelines for Standardization Work Provisions 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
After the sample is dissolved in nitric acid and hydrofluoric acid, the nitrogen oxides are reduced with hydrogen peroxide, lead is added to reduce the loss of platinum on the anode, and copper is electrolyzed to precipitate on the platinum cathode, dried, and weighed. The amount of copper remaining in the electrolyte is determined by atomic absorption spectrometry. 4 Reagents
4.1 Anhydrous ethanol.
4.2 Hydrofluoric acid (pl.13g/mL).
4.3 Nitric acid (1+1).
4.4 Hydrogen peroxide (1+9).
4.5 Ammonium chloride solution (0.02g/L).
4.6 Lead nitrate solution (10g/L).
4.7 Copper standard stock solution: Weigh 1.0000g pure copper, place in a 250mL beaker, add 40mL nitric acid (4.3), cover with 1 beaker. Heat until completely dissolved, boil to remove nitrogen oxides, wash beaker and beaker with water, cool. Transfer to a 1000ml volumetric flask. Dilute to full scale with water, mix. This solution contains 1mg copper in 1mL. 4.8 Copper standard solution: Transfer 10.00mL copper standard stock solution, place in a 500ml volumetric flask, dilute to scale with water, mix. This solution contains 20μg copper in 1mL.
5 Instruments
5.1 Electrolyzer equipped with automatic stirring device and precision DC ammeter and voltmeter. Approved by the State Administration of Technical Supervision in 1996-1104
Implementation on April 1, 1997
GB/T 5121.1-1996
5.2 Platinum cathode: platinum wire with a diameter of about 0.2 mm is woven into a mesh with a mesh size of about 36 m per square centimeter. It is made into a mesh※circular shape. See Figure 1.
5.3 Platinum anode: spiral shape. See Figure 2
Figure 1 Platinum cathode
5.4 Atomic absorption spectrometer, with copper hollow cathode lamp. Under the best working conditions of the instrument, those that can meet the following indicators can be used. Figure 2 Platinum electrode
Sensitivity: In a solution consistent with the matrix of the sample solution, the characteristic concentration of copper should not be greater than (0.0121g/ml. Precision: The standard deviation of measuring the absorbance 10 times with the highest concentration standard solution should not exceed 1.0 of the average absorbance ※: The standard deviation of measuring the absorbance 10 times with the lowest concentration standard solution (not the "zero" standard solution) should not exceed 0.5% of the average absorbance of the highest concentration standard solution.
Linear curve: The working curve is divided into 5 sections according to the concentration. 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.
For instrument working conditions, see Appendix A (Suggested Appendix). 6 Analysis steps
6.1 Test material
Weigh 2.000g of sample to an accuracy of 0.0001g. Perform the determination independently and take the average value. 6.2 Blank test
Perform a blank test with the test material (electrolysis is not required). 6.3 Determination
GB/T 5121. 1--1996
6.3.1 Place the sample (6.1) in a 250mL polytetrafluoroethylene or polypropylene beaker, add 2ml hydrofluoric acid and 30ml nitric acid. Cover the beaker. When the reaction is almost finished, heat at no more than 80°C until the sample is completely dissolved. Add 25mL hydrogen peroxide and 3ml lead nitrate solution. Wash the beaker and the wall of the beaker with ammonium chloride solution and dilute the volume to about 150ml. 6.3.2 Install the platinum anode and the accurately weighed platinum cathode on the electrolyzer so that the net is completely immersed in the solution. Cover the beaker with a split polytetrafluoroethylene or polyolefin.
6.3.3 Perform electrolysis with a current density of 1.0A/dm while stirring. Electrolyze to copper When the color fades, wash the surface of the beaker, the cup wall and the electrode rod with water, and continue electrolysis for 30 minutes. If copper is precipitated on the newly immersed electrode, it means that the electrolysis is complete. 6.3.4 Without cutting off the current, slowly lift the electrode or lower the beaker, immediately rinse the electrode alternately with two cups of water, quickly remove the electrode, and immerse it in a cup of anhydrous ethanol in turn. Immediately put it in a 105°C constant temperature drying oven to dry for 3 to 5 minutes, take it out and place it in a desiccator + cool it to room temperature and weigh it.
6.3.5 Transfer the solution after electrolysis of copper (6.3.4) and the first cup of water for washing the electrode (6.3.4) into two 300ml beakers A, cover with surface resistor, evaporate to a volume of about 80ml, and cool. Transfer the combined solution into a 200ml volumetric flask, dilute to scale with water, mix and observe the residual copper content is greater than 0.0005g, transfer 25.00mL of solution (6.3.5), place it in a 100ml volumetric flask, dilute to scale with water and mix. 6.3.6 Use air-acetylene flame on the atomic absorption spectrometer, at a wavelength of 324.7nm, and adjust the absorbance of the test solution with water at zero at the same time as the standard solution series. Subtract the absorbance of the blank solution accompanying the sample from the measured absorbance, and calculate the corresponding copper concentration from the working curve. 6.4I Plotting the curve
6.4.1 Transfer 0, 2.50.5.00, 7.50.10.00, 12.50ml of copper standard solution to a group of 100ml volumetric flasks, add 5ml of nitric acid respectively, dilute to scale with water, and mix. 6.4.2 Under the same conditions as the sample dissolution wave determination, measure the absorbance of the standard solution series, subtract the absorbance of the "winter" concentration solution in the standard solution series, and draw a working curve with copper concentration as the horizontal axis and absorbance as the vertical axis. 7 Expression of analysis results
Calculate the percentage of copper according to formula (1):
Cu(%) [(m=m) + : V. . V, × 10-me
where: ml——total mass of platinum cathode and deposited copper, gm2-mass of platinum cathode, g
c-copper concentration obtained from the working curve, μg/mL; V-total dilution volume of residual copper solution after electrolysis, mL; V.--dilution volume after taking part of the residual copper solution, mi.; V,-volume of the residual copper solution taken partly, mL.mm--mass of the sample, g.
The obtained result is expressed to two decimal places.
8 Allowable difference
The difference between the analysis results of laboratories should not exceed 0.15%. ma·V
Part II Method 2 Electrolysis-spectrophotometry
9 Scope
This standard specifies the determination of copper content in copper and processed copper. This standard is applicable to the determination of copper content in copper and processed copper. Determination range: >99.00%~~99.98%)
10 Referenced standards
GB/T5121.7 1996
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions 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 GB7729-87 General Principles for Spectrophotometric Methods for Chemical Analysis of Metallurgical Products 11 Summary of the Method
The sample is dissolved in a mixed acid, and after adjusting the volume of the solution, electrolysis is performed at a low current. After the electrolysis is terminated, the platinum cathode is washed with water and anhydrous ethanol, dried, cooled, and weighed. The electrolyzed solution is measured by spectrophotometry to determine the residual copper content, and after correction, the total amount of copper is obtained. 12 Reagents
12.1 Anhydrous ethanol.
12.2 Nitric acid (1+1).
12.3 Ammonia water (1+1).
12.4 Mixed acid: 7 units of nitric acid (pl.42 g/mL), 10 units of sulfuric acid (pl.84 g/mL) and 25 units of water, mix and cool.
12.5 Mixed acid: Take 42 mL of mixed acid (12.4) in a 500 mL volumetric flask, dilute to the mark with water, and mix. 12.6 Ammonium citrate solution: (500 g/L). 12.7 Dicyclohexanone oxalyl dihydrochloride (BCO) (1 g/L): Weigh 0.5 g of BCO in a 300 mL beaker, add 50 mL of ethanol and 200 ml of warm water to dissolve, then transfer to a 500 ml volumetric flask, dilute to the mark with water, and mix. 12.8 Copper standard stock solution: Weigh 0.1000g pure copper into a 150mL beaker, add 10mL nitric acid (12.2), heat at low temperature until completely dissolved, boil to remove nitrogen oxides, wash Table III and the beaker wall with water, and cool. Transfer to a 1000mL volumetric flask, dilute to scale with water, and mix well. This solution contains 100μg copper in 1mL. 12.9 Copper standard solution: Pipette 10.100mL copper standard stock solution is placed in a 100mL volumetric flask, diluted to the mark with water, and mixed. 1mL of this solution contains 10μg copper.
12.10 Neutral red ethanol solution: (1g/L). 13 Instruments
13.1 Electrolyzer equipped with automatic stirring device and precision ammeter and voltmeter. 13.2 Electric constant temperature drying oven.
13.3 Platinum cathode: Use platinum wire with a diameter of about 0.2mm to weave a mesh with a mesh of about 36μm per square centimeter to make a mesh circular shape. See Figure 1 in Method 1.
13.4 Platinum anode: spiral. See Figure 2 in Method 1. 13.5 Spectrophotometer.
14 Sample
If the sample has been oxidized, weigh the required amount of sample and place it in a beaker, add 100ml of glacial acetic acid (1+4), heat and boil for 2-3 minutes, discard the solution, rinse the sample with water until it has no acid smell, wash it twice with anhydrous ethanol, take it out, and immediately cover it in an electric constant temperature drying oven at about 105°C to dry for 3-5 minutes after the anhydrous ethanol evaporates, take it out, and place it in a desiccator for later use. 198
15 Analysis steps
15.1 Sample
GB/T 5121. 1-- 1996
Weigh 5.005-5.007g of sample, accurate to 0.0001g. Perform two independent measurements and take the average value. 15.2 Determination
15.2.1 After weighing the sample, place the platinum cathode and weigh the total amount of the sample and the platinum cathode. Take out the platinum cathode and put it in a desiccator. Place the sample (15.1) in a 250mL tall beaker, cover it with Table III, slowly add 42ml along the beaker mouth, and cool the mixed acid (12.4) until the reaction almost stops. TF
15.2.2 Heat the beaker (15.2.1) at 80~~90℃ until the sample is completely dissolved. Continue heating for 1.5~2h to drive off nitrogen oxides. Remove and cool slightly. Wash the beaker wall and surface with water and dilute the solution to a volume of about 150ml. Put in a magnetic stirring bar and place the beaker on the electrolyzer tray! Turn on the stirring device, stir the solution evenly and then stop stirring. 15.2.3 Install the platinum cathode and platinum anode on the electrolyzer and place them in the solution, so that the platinum electrode is close to the bottom of the beaker, and cover the tall beaker with two and a half pieces of Table I.
15.2.4 Carry out electrolysis at a current density of about 0.6A/dm2 on the cathode surface until the solution becomes colorless (about 17 hours), wash the two half-sheets of Table III, the cup wall and the electrode rod with water, reduce the current density to 0.3A/dm2 and continue electrolysis until the electrode rod newly submerged in water no longer deposits copper.
15.2.5 Without cutting off the power supply, quickly remove the tall beaker and replace it with a tall beaker containing about 180mL of water, and continue electrolysis for 15 minutes. 15.2.6 Immediately extract the platinum cathode and pour it into another 250ml beaker filled with water, move it up and down 3 times, turn off the power supply, remove the electrode and place it in a beaker containing anhydrous ethanol, and immediately place it in a 105℃ electric constant temperature drying oven to dry for 3 to 5 minutes, remove it and cool it to room temperature in a desiccator.
15.2.7 Weigh the platinum cathode after electrolytic deposition with the original balance. 15.2.8 Determine the amount of residual copper in the solution after electrolysis as follows. 15.2.8.1 Blank test
Pipette the same amount of mixed acid (12.4) as the sample solution into a 50-mL volumetric flask and perform a blank test along with the sample. 15.2.8.2 Place the electrolyte after electrolysis and a cup of water from the electrolysis for 15 min into a 500-mL volumetric flask, dilute to scale with water, and mix. 15.2.8.3 Pipette 10.00-20.00 mL into a 50-mL volumetric flask, add 2 mL of ammonium citrate solution, dilute to about 200 mL with water, add 2-3 drops of neutral red solution, and neutralize with nitrogen-water solution until the red color fades and an excess of 1.0 mL is added. Add 8.0 ml of dicyclohexanone oxalyl distilled water solution, dilute to scale with water, mix well, and let stand for 20 minutes. 15.2.8.4 Transfer part of the solution into a 2 cm absorption III, and measure the absorbance at a wavelength of 600 nm using the blank solution accompanying the sample as a reference. Find the corresponding copper content from the working curve. 15.2.9 Drawing of working curve
15.2.9.1 Take 6 portions of 20.0ml mixed acid (12.5) and place them in a group of 50mL volumetric flasks. Add 0.1.00, 2.00.3.00.4.00, and 5.00mL of copper standard solution respectively. The following shall be carried out according to the "addition of ammonium citrate solution" in 15.2.8.3. 15.2.9.2 Transfer part of the solution into a 2cm absorption blood, use the reagent blank as a reference, measure the absorbance at a wavelength of 600nm on a spectrophotometer, and draw a working curve with the copper content as the horizontal axis and the absorbance as the vertical axis. 16 Expression of analysis results
Calculate the percentage of copper according to formula (2):
Cu(%)
-- m-m2 + ma - VoX 10
mo·Vi
Wu Zhong: m~total mass of sample and platinum cathode, g; m.---total mass of platinum cathode and deposited copper after electrolysis·g; <100
5121.1- 1996
The amount of copper found on the working curve, ug; Vu—the total volume of the residual copper solution diluted after electrolysis, ml.; V—the volume of the residual copper solution taken, ml.; mg--the mass of the sample, g.
The result is expressed to two decimal places.
Allowable difference
The difference in analysis results between laboratories should not exceed 0.02%. 200
GB/T5121.1--1996
Appendix A
(Suggestive Appendix)
Instrument working conditions
The working conditions for measuring copper using WFZ-11) atomic absorption spectrophotometer are shown in Table A1. Table A18 Determine the amount of residual copper in the solution after electrolysis as follows. 15.2.8.1 Blank test
Pipette the same amount of mixed acid (12.4) as the sample solution into a 50mL volumetric flask and perform a blank test together with the sample. 15.2.8.2 Place the electrolyte after electrolysis and a cup of water from the electrolysis for 15 minutes into a 500mL volumetric flask, dilute to scale with water, and mix well. 15.2.8.3 Pipette 10.00~20.00mL into a 50mL volumetric flask, add 2mL of ammonium citrate solution, dilute to about 200mL with water, add 2~3 drops of neutral red solution, and neutralize with nitrogen water solution until the red color fades and an excess of 1.0mL is added. Add 8.0 ml of dicyclohexanone oxalyl distilled water solution, dilute to scale with water, mix well, and let stand for 20 minutes. 15.2.8.4 Transfer part of the solution into a 2 cm absorption III, and measure the absorbance at a wavelength of 600 nm using the blank solution accompanying the sample as a reference. Find the corresponding copper content from the working curve. 15.2.9 Drawing of working curve
15.2.9.1 Take 6 portions of 20.0ml mixed acid (12.5) and place them in a group of 50mL volumetric flasks. Add 0.1.00, 2.00.3.00.4.00, and 5.00mL of copper standard solution respectively. The following shall be carried out according to the "addition of ammonium citrate solution" in 15.2.8.3. 15.2.9.2 Transfer part of the solution into a 2cm absorption blood, use the reagent blank as a reference, measure the absorbance at a wavelength of 600nm on a spectrophotometer, and draw a working curve with the copper content as the horizontal axis and the absorbance as the vertical axis. 16 Expression of analysis results
Calculate the percentage of copper according to formula (2):
Cu(%)
-- m-m2 + ma - VoX 10
mo·Vi
Wu Zhong: m~total mass of sample and platinum cathode, g; m.---total mass of platinum cathode and deposited copper after electrolysis·g; <100
5121.1- 1996
The amount of copper found on the working curve, ug; Vu—the total volume of the residual copper solution diluted after electrolysis, ml.; V—the volume of the residual copper solution taken, ml.; mg--the mass of the sample, g.
The result is expressed to two decimal places.
Allowable difference
The difference in analysis results between laboratories should not exceed 0.02%. 200
GB/T5121.1--1996
Appendix A
(Suggestive Appendix)
Instrument working conditions
The working conditions for measuring copper using WFZ-11) atomic absorption spectrophotometer are shown in Table A1. Table A18 Determine the amount of residual copper in the solution after electrolysis as follows. 15.2.8.1 Blank test wwW.bzxz.Net
Pipette the same amount of mixed acid (12.4) as the sample solution into a 50mL volumetric flask and perform a blank test together with the sample. 15.2.8.2 Place the electrolyte after electrolysis and a cup of water from the electrolysis for 15 minutes into a 500mL volumetric flask, dilute to scale with water, and mix well. 15.2.8.3 Pipette 10.00~20.00mL into a 50mL volumetric flask, add 2mL of ammonium citrate solution, dilute to about 200mL with water, add 2~3 drops of neutral red solution, and neutralize with nitrogen water solution until the red color fades and an excess of 1.0mL is added. Add 8.0 ml of dicyclohexanone oxalyl distilled water solution, dilute to scale with water, mix well, and let stand for 20 minutes. 15.2.8.4 Transfer part of the solution into a 2 cm absorption III, and measure the absorbance at a wavelength of 600 nm using the blank solution accompanying the sample as a reference. Find the corresponding copper content from the working curve. 15.2.9 Drawing of working curve
15.2.9.1 Take 6 portions of 20.0ml mixed acid (12.5) and place them in a group of 50mL volumetric flasks. Add 0.1.00, 2.00.3.00.4.00, and 5.00mL of copper standard solution respectively. The following shall be carried out according to the "addition of ammonium citrate solution" in 15.2.8.3. 15.2.9.2 Transfer part of the solution into a 2cm absorption blood, use the reagent blank as a reference, measure the absorbance at a wavelength of 600nm on a spectrophotometer, and draw a working curve with the copper content as the horizontal axis and the absorbance as the vertical axis. 16 Expression of analysis results
Calculate the percentage of copper according to formula (2):
Cu(%)
-- m-m2 + ma - VoX 10
mo·Vi
Wu Zhong: m~total mass of sample and platinum cathode, g; m.---total mass of platinum cathode and deposited copper after electrolysis·g; <100
5121.1- 1996
The amount of copper found on the working curve, ug; Vu—the total volume of the residual copper solution diluted after electrolysis, ml.; V—the volume of the residual copper solution taken, ml.; mg--the mass of the sample, g.
The result is expressed to two decimal places.
Allowable difference
The difference in analysis results between laboratories should not exceed 0.02%. 200
GB/T5121.1--1996
Appendix A
(Suggestive Appendix)
Instrument working conditions
The working conditions for measuring copper using WFZ-11) atomic absorption spectrophotometer are shown in Table A1. Table A1
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