SJ/T 10940-1996 Analysis of chromium oxide in color picture tube glass SJ/T10940-1996 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Analysis of chromium oxide (Cr2Os) in color picture tube glass
GB9474.5-88
Reduced to SJ/T10940-96
This standard specifies the analysis method of chromium oxide, which is applicable to the analysis of chromium oxide in electronic glass such as color picture tubes and black and white picture tube glass shells. This method should be analyzed in accordance with the provisions of GB9000.1 "General Principles of Chemical Analysis Methods for Electronic Glass". 1 Method Summary
The sample is decomposed by hydrofluoric acid-sulfuric acid, the residue is dissolved with dilute sulfuric acid, and the sulfate precipitate is separated by filtration. The chromium is oxidized with potassium permanganate to a hexavalent state, and diphenylcarbazide is used to develop the color and the determination is carried out on a spectrophotometer. 2 Reagents and solutions
2.1 Hydrofluoric acid 40%;
2.2 Sulfuric acid 1#1,
2.3 Potassium permanganate solution 5%;
2.4 Urea solution 20%;
2.5 Sodium sulfite solution 10%www.bzxz.net
2.6 Sodium nitrite solution 10%;
2.7 Ammonium ferric sulfate solution containing Felmg/ml
Accurately weigh 0.864g of ammonium ferric sulfate, add 50ml water and 5ml 1:1 sulfuric acid, dissolve it and transfer it into a 100ml volumetric flask, dilute it to the scale with water, shake it well and set aside.
2.8 Diphenylcarbohydrazide [CisHuN,O] 0.2% ethanol solution (prepare it when using). 2.9 Chromium oxide standard solution contains Cr0g100μg/ml Accurately weigh 0.1936g of potassium dichromate (reference reagent) in a beaker, add water to dissolve, transfer to a 1000ml volumetric flask, dilute to scale with water, and shake well.
2.10 Chromium oxide standard dilution solution contains Cr20s5ug/ml Pipette 25ml of chromium oxide standard solution (2.9) into a 500ml volumetric flask, dilute to scale with water, and shake well. 3 Analysis steps
3.1 Accurately weigh 1.00g of sample in platinum evaporating blood, moisten with a small amount of water, add 15ml of hydrofluoric acid, 5ml of sulfuric acid (1:1), and 5~6 drops of sodium sulfite solution. Heat to decompose. Evaporate until white sulfuric acid smoke begins to appear and stop heating immediately. After cooling, add 15ml of hydrofluoric acid, continue heating for 3min until white sulfuric acid smoke appears, remove the platinum blood and cool. Note: Cr:O, easy to volatilize and lose during evaporation, so it cannot be evaporated, and the sulfuric acid tube smoke time should be strictly controlled. 3.2 Add about 40ml of water and 4ml of sulfuric acid (1:1), cover with a watch glass and heat in a water bath for about 30min to dissolve the salts. If there is precipitation, filter it with slow filter paper, wash it with water 7 to 8 times, and discard the precipitation. Collect the filtrate and washing liquid in a 200ml beaker. If there is no precipitation, transfer the solution directly to the beaker.
Approved by the Ministry of Electronics Industry of the People's Republic of China on April 29, 1988TTTKKAca
Implementation on December 1, 1988
GB9474.5—88
3.3 Add 4ml of ammonium ferric sulfate solution, dilute it with water to about 70ml, add 2ml of potassium permanganate solution while boiling, and continue to boil until the solution volume is about 60ml.
3.4 ​​Cool. Add 10ml of urea solution, and add sodium nitrite solution dropwise while stirring until the purple color of potassium permanganate just disappears. 3.5 Transfer this solution into a 100ml volumetric flask and add 2ml of diphenylcarbazide ethanol solution. Dilute with water to the mark and shake well. 3.6 After standing for 5min, use 2cm colorimetric blood and reagent blank as reference to measure the absorbance at a wavelength of 540nm. 3.7 Drawing of standard curve
Put 0, 1, 2, 3, 4, 5ml of chromium oxide standard dilution in 2.10 into a 200ml beaker, add water to about 30ml, add 4ml of sulfuric acid (1:1), and shake well. The following analysis steps are carried out according to 3.3 to 3.6 to draw the working curve of chromium oxide content. 4 Calculation
According to the absorbance of the chromium trioxide sample solution, find out the amount equivalent to chromium oxide from the standard curve. Calculate the content of chromium trioxide according to the following formula.
Cr:0% =X× 10-
Wherein: X—the amount of Cr2Os found from the standard curve, ug, W——the sample weight, 8.
Additional remarks:
This standard was drafted by Factory 4400 of the Ministry of Electronics Industry and the Institute of Standardization. 2
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