This standard specifies the determination of aluminum in high-purity quartz sand. This standard is applicable to the analysis of various grades of high-purity quartz sand. SJ 3228.8-1989 Determination of aluminum in high-purity quartz sand SJ3228.8-1989 Standard download decompression password: www.bzxz.net
This standard specifies the determination of aluminum in high-purity quartz sand. This standard is applicable to the analysis of various grades of high-purity quartz sand.

Standard of the Ministry of Machinery and Electronics Industry of the People's Republic of China Determination of aluminum in high-purity quartz sand
1 Subject content and scope of application
1.1 Subject content
This standard specifies the determination of aluminum in high-purity quartz sand. 1.2 Scope of application
This standard is applicable to the analysis of high-purity quartz sand of various grades. 2 Reference standards
SJ3228.2-89www.bzxz.net
9 General rules for analysis of high-purity quartz sand.
3 Method summary
SJ3228.8-89
Aluminum and chrome cyanine R generate a red-purple complex in an acetic acid buffer solution with a pH of 3.86. When the pH value is low, aluminum develops color faster, but the reagent blank layer is darker. When the pH value is high, aluminum color development is unstable. This method adopts the method of developing color at a lower pH value, and then adding a buffer solution to increase the pH value of the solution, which can achieve good results. 4 Reagents
4.1 Chromic acid R solution: weigh 0.375g chromic acid R into a 100ml beaker, add 25g sodium chloride, 25g ammonium nitrate and 2ml nitric acid. After stirring, dissolve and dilute with water to a 500ml volumetric flask and store in a brown bottle. 4.2 Ammonium acetate buffer solution: take 320g ammonium acetate, add 700-800ml water, adjust the pH to 6 with glacial acetic acid (measured with a pH meter),
4.3 Methyl orange solution: 0.1%,
4.4 Copper iron reagent solution: 5%
4.5 Ethyl acetate
4.6 Aluminum standard solution: 0.01mgm1-1.
5 Analysis steps
Accurately weigh 1g of the sample after drying at 110℃, place it in the lining of the high-pressure crucible, moisten it with water, add 6ml of hydrofluoric acid, 2ml of 1:1 hydrochloric acid, shake it gently, cover the lining, put it in a stainless steel sleeve, tighten the lid, and place it in a constant temperature drying oven at 145℃ to dissolve for 2h. After cooling to room temperature, open the lid, gently push out the lining, place it on a 120℃ hot plate to evaporate to dryness, add 2ml of 1:1 hydrochloric acid, transfer it to a 60ml separatory funnel, and add 5% copper iron reagent. Make the iron precipitate completely (this reagent can be omitted if there is no precipitation), add 5ml of ethyl acetate (chloroform can also be used), and shake for 5min. After stratification, move the water tank to another separatory funnel, wash the organic phase with a small amount of water and discard it, combine the aqueous phase, and extract it twice with ethyl acetate (5 ml each time), boil it for 3-5 minutes, and cool it. Move it to a 100ml volumetric flask, add 1 drop of methyl orange indicator, adjust the indicator to yellow with 1:1 ammonia water, and then add 1:1 hydrochloric acid. When the indicator turns red, dilute it to 25ml with water, add 5ml of chrome cyanine R solution with a pipette, let it stand for 5 minutes, then add 10ml of ammonium acetate buffer solution with a pipette, dilute it to the scale with water and shake it well for colorimetric determination. (If using a photoelectric colorimeter, use a 1cm colorimetric tank at a wavelength of 530nm). At the same time, make a reagent blank and a series of standard sample solutions for comparison under the same conditions. 6 Calculation
A1 (%) =
m·1000
Wherein, V-volume of standard solution consumed. m, C—concentration of aluminum standard solution. mg·ml-1, m sample weight. g.
Additional remarks:
This standard was proposed by the Electronic Standardization Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the 18th Research Institute of the Ministry of Machinery and Electronics Industry and Hubei Guangshui Quartz Powder Factory. The main drafters of this standard: Qin Guozhen, Sheng Jianguo. 2
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