GB/T 15064.8-1994 Test method for graphite emulsion of picture tubes - Test method for iron and copper content
Some standard content:
National Standard of the People's Republic of China
Test method for graphite emulsion of kinescope
Test method for iron and copper contents
Method for iron and copper contents of colloidal graphite for kinescope Subject content and scope of application
This standard specifies the test method for determining the iron and copper contents of colloidal graphite for kinescope. This standard is applicable to the determination of the iron and copper contents of black-bottom graphite emulsion of color picture tubes. GB/T 15064.8—94
This standard lists two methods for determining copper content: the new cuproline-methyl orange extraction photometry and the atomic absorption spectrophotometry. 2 Reference standards
GB/T15064.1 Test methods for graphite emulsions of picture tubes Test methods for solid content, volatile matter, ash content and pH value 3 Determination of iron by sulfosalicylic acid complexometric titration
3.1 Method summary
At pH 1.8-2.5, use sulfosalicylic acid as an indicator and titrate iron with disodium ethylenediaminetetraacetate (EDTA) standard solution. 3.2 Reagents
3.2.1 Hydrochloric acid (superior purity): 50% (V/V), 2% (V/V). 3.2.2 Ammonia water: 50% (V/V).
3.2.3 EDTA standard solution: 0.005 mol/L. 3.2.3.1 Preparation: Weigh 1.8 g of disodium ethylenediaminetetraacetate and dissolve it in a small amount of water, transfer it into a 1000 mL volumetric flask, dilute it to the mark with water and shake it well.
3.2.3.2 Calibration: According to the calibration method specified in Article 17 of GB601, the weight of the standard zinc oxide is 0.1g. The titer Tee (mg/mL) of EDTA for iron is calculated according to formula (1): Tre = MX 55. 85
Wherein: M---
-Concentration of the calibrated EDTA standard solution, mol/L. 55.85-
Number of grams of Fe per gram molecule, g/mol;
55.85-——The mass of iron equivalent to 1.00mol EDTA standard solution (Cc(EDTA)=1.00mol/L), mg3.2.4 Sodium sulfosalicylate indicator solution: 100g/L. 3.3 Instruments and equipment
a. High temperature electric furnace: working temperature 700℃; b. Balance: sensitivity 0.0001g;
c. Electric heater.
3.4 Test specimen: Prepare the test specimen in accordance with the provisions of Chapter 3 of GB/T15064.8-94. 3.5 Preparation of test solution
Approved by the State Administration of Technical Supervision on April 18, 1994 (1)
Implemented on December 1, 1994
GB/T 15064.8-94
Weigh about 3~~5g sample (accurate to 0.0001g), put it in a 100mL beaker, add 20mL of 50% hydrochloric acid, and boil it slightly on an electric heater for about 30min. Filter it with quantitative filter paper into a 50mL volumetric flask, scrub the beaker with 2% hydrochloric acid and wash the filter residue 6~8 times, then wash it with water 4~5 times, move the filter paper and filter residue into platinum together, place the crucible cover obliquely on the crucible, fully ash it on an electric heater, move it into a high-temperature electric furnace that has been heated to 700℃, half-open the furnace door, burn it for 30~40min, take it out, cool it slightly, add 3mL of 50% hydrochloric acid, steam it until it becomes a paste, then add 10mL of 2% hydrochloric acid, heat it to a slight boil for about 5min, filter it into the original volumetric flask, combine it with the original filtrate, wash the crucible and filter residue 6~8 times with 2% hydrochloric acid, dilute it to the scale of the volumetric flask with water, shake it well and set it aside. 3.6 Analysis steps
Accurately pipette 50mL of the test solution prepared in 10.1.5 into a 200mL beaker, dilute with water to about 50mL, add 6-8 drops of sodium sulfosalicylate indicator, add 50% ammonia water to adjust the pH value of the solution to 1.5-2.0 (check with precision pH test paper), heat the solution to 60-70℃, and titrate with EDTA standard solution until the solution changes from purple to yellow. The titration speed should not be too fast and must be fully stirred. 3.7 Result calculation
3.7.1 Iron content X, (ppm) is calculated according to formula (2): Xi- To.
Where: TreEDTA standard solution titration degree for iron, mg/mL; V--the volume of standard solution consumed during titration, mLm1--the mass of the sample, g.
3.7.2 Take the arithmetic mean of the results of two parallel samples as the test result. The difference between the two measured values shall not exceed 150ppm in the same laboratory and 300ppm in different laboratories. Otherwise, the third sample shall be measured and the test result shall be calculated based on the two measured values that do not exceed the difference.
4 Determination of copper by neocuproine-methyl orange extraction spectrophotometry 4.1 Method summary
Under the condition of pH 6-9.5, sodium sulfite is used to reduce copper to monovalent copper. Monovalent copper and neocuproine form a ternary complex in the presence of methyl orange and are extracted by chloroform. The maximum absorption is at 420nm and the complex is very stable. When the masking agent potassium sodium tartrate is present, other elements do not affect the determination of copper, especially allowing the presence of a large amount of divalent and trivalent metal elements such as iron, calcium, and magnesium. 4.2 Reagents
4.2.1 Chloroform.
4.2.2 Neocuproline (2,9-dimethyl-1,10-phenanthroline) ethanol solution: 1.5g/L. 4.2.3 Methyl orange solution: 0.4g/L.
4.2.4 Anhydrous sodium sulfite solution: 100g/L. Purification method: Transfer 300mL of anhydrous sodium sulfite solution into a 500mL separatory funnel, add 1 drop of phenol red solution, add ammonia solution to neutralize until slightly red, add 10mL of neocuproline ethanol solution, and extract with 10mL of chloroform each time until the organic layer is colorless, discard the organic layer, and transfer the aqueous phase into a reagent bottle for later use. 4.2.5 Potassium sodium tartrate solution: 500g/L. Purification method: transfer 300mL potassium sodium tartrate solution into a 500mL separatory funnel, add 20mL anhydrous sodium sulfite solution, add 10mL new cuprous solution, shake well, let stand for 5min, add 10mL chloroform each time to extract until the organic layer is colorless. Discard the organic layer and transfer the aqueous phase into a reagent bottle for later use.
4.2.6 Ammonia solution: 50% (V/V)
Purification method: add ammonia water and 2g sodium hydroxide to the bottom of a large dryer, place a 500mL plastic beaker containing 300mL distilled water on the porcelain plate of the dryer, and cover the dryer. Take out the beaker after 6-7 days and transfer the solution in the beaker into a plastic bottle for later use. 4.2.7 Copper standard solution: Weigh 1.0000g of pure copper (99.99%), dissolve it in a small amount of dilute nitric acid in a beaker, heat and evaporate to dryness, add 3mL of hydrochloric acid (density 1.19) and a few milliliters of water and boil, transfer to a 1000mL volumetric flask after cooling, dilute to the mark with water, shake and set aside. 320
4.2.8 Phenol red solution: 2.5g/L.
GB/T15064.8-94
Weigh 0.25g of phenol red reagent, add 5mL of 5g/L sodium hydroxide solution to dissolve, and dilute to 100mL with water. 4.3 Instruments and equipment
Spectrophotometer.
4.4 Analysis steps
4.4.1 Draw a standard curve
Put 0, 1.0, 2.0, 3.0, 4.0, 5.0mL of copper standard solution (equivalent to 0, 1.0, 2.0, 3.0, 4.0, 5.0ug copper, respectively) in a 60mL separatory funnel, dilute to about 10mL with water, add 5mL of potassium sodium tartrate solution, and shake well. Add 1 drop of phenol red solution and adjust with ammonia solution until the solution is slightly red (pH value is about 7). Add 5mL of anhydrous sodium sulfite solution and shake well. Accurately add 1mL of new cuprous solution, shake well, and let it stand for 10min. Accurately add 1.0mL of methyl orange solution and shake well. Accurately add 10.0mL of chloroform, extract for 1min, let stand for stratification, and then input the organic layer into a dried colorimetric tube. On a spectrophotometer, use the reagent blank as a reference and 1cm of colorimetric blood to measure the absorbance at a wavelength of 420nm. Use the measured absorbance as the ordinate and the corresponding concentration as the abscissa to draw a standard curve. 4.4.2 Sample determination
Take 10.0mL of the test solution prepared in 3.5, place it in a 60mL separatory funnel, add 5mL of potassium sodium tartrate solution, and shake well. Follow the steps for drawing a standard curve and measure the absorbance. The corresponding copper content is obtained from the standard curve. 4.5 Calculation of results
4.5.1 Calculate the copper content X2 (ppm) according to formula (3): X
Wherein: c——the copper content in the solution to be tested obtained from the standard curve, ugm2——the mass of the sample, g;
V,—the volume of the sample solution, mL; V2—the volume of the entire sample solution, mL. · (3)
4.5.2 Take the arithmetic mean of the results of the two parallel samples as the test result. The difference between the two measured values shall not exceed 0.4ppm. Otherwise, the third sample shall be measured and the test result shall be calculated based on the two measured values that do not exceed the tolerance. 5 Atomic absorption spectrophotometry
5.1 Instruments and equipment
Atomic absorption spectrophotometer (flame type: air-acetylene). 5.2 Reagents
5.2.1 Copper standard solution: Prepare according to the provisions of 4.2.7. 5.2.2 Preparation of standard solution series for determination Take 0, 2.0, 4.0, 6.0, 8.0mL of copper standard solution (equivalent to 0, 2.0, 4.0, 6.0, 8.0μg copper, respectively) in a 50mL volumetric flask, dilute to the scale with water, and shake well.
5.3 Analysis stepswww.bzxz.net
Adjust the instrument according to the selected instrument working conditions. After the hollow cathode lamp is preheated for 20 minutes, ignite the flame. After normal combustion, adjust the air and acetylene flow rates, and adjust the zero point with water spray. Then spray with the standard solution series and the sample solution prepared in 3.5, respectively, and read the corresponding absorbance. The same solution is measured twice, and the standard curve is drawn by the difference between the average absorbance of the standard solution and the blank absorbance and the standard solution concentration series. According to the difference between the absorbance of the sample solution and the blank absorbance, the copper content in the sample solution can be directly checked on the curve. 5.4 Result calculation
5.4.1 Copper content X: (ppm) Calculate according to formula (4): 321
Wu Zhong: ci—
-Copper content in sample solution,;
coCopper content in blank solution, ug;
-Mass of sample, g.
5.4.2 Calculate the test results in accordance with 4.5.2. Additional Notes:
GB/T 15064. 8 -- 94
This standard is proposed by the State Administration of Building Materials Industry. This standard is under the jurisdiction of Shandong Nanshu Graphite Mine. This standard was drafted by Shandong Nanshu Graphite Mine and Weiyang Non-metallic Mineral Research Institute of the State Administration of Building Materials. The main drafters of this standard are Liu Huidong, Wei Zaijin, Zhang Youyuan and Liu Youhong. 322
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