GB/T 5195.7-1985 Chemical analysis method of fluorite - Molybdenum blue-rhodamine B spectrophotometric method for determination of phosphorus content GB/T5195.7-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis methods of fluorsparbzxZ.net
Molybdenum blue - rhodamine B photometric method for the determination of phosphorus contentMethods for chemical analysis of fluorsparThe molybdenum blue - rhodamine B photometricmethod for the determination of phosphorus contentThis standard is applicable to the determination of phosphorus content in fluorspar. Determination range: 0.0003～0.0050%. This standard complies with GB1467--78 "General Principles and General Provisions of Standards for Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
UDC549.454
:543-42
GB5195.7—85
The sample is decomposed with hydrofluoric acid, arsenic is removed with hydrobromic acid, ascorbic acid-hydroxylamine hydrochloride is used as a reducing agent, ammonium molybdate is added at 1N hydrochloric acid acidity to form phosphorus blue, and then rhodamine B is added to form a ternary complex. Measure its absorbance at a wavelength of 585nm on a spectrophotometer. 2 Reagents
2.1 Hydrochloric acid (specific gravity 1.19).
2.2 Hydrochloric acid (1→1).
2.3 Hydrofluoric acid (specific gravity 1.15): high-grade pure. 2.4 Hydrobromic acid (specific gravity 1.38): high-grade pure. 2.5 Perchloric acid (specific gravity 1.67): high-grade pure. 2.6 Ammonium molybdate solution (4%): Weigh 4g of ammonium molybdate [(NH4). Mo024·4H20], place in a beaker, add appropriate amount of water, heat to dissolve, cool, dilute to 100ml with water, mix, and filter. 2.7 Polyvinyl alcohol (average degree of polymerization is 2400-2500) solution (0.5%): Weigh 0.5g polyvinyl alcohol, place in a beaker, add appropriate amount of hot water to boil and dissolve, dilute with water to 100ml after cooling, mix well, and filter. 2.8 Rhodamine B solution (0.02%): Weigh 0.05g rhodamine B, place in a beaker, add appropriate amount of water to dissolve, dilute with water to 250ml, and mix. Store in a brown bottle. 2.9 Mixed reducing agent: Ascorbic acid solution (5%) and hydroxylamine hydrochloride solution (5%), mix by (2+1) volume. 2.10 Phosphorus standard stock solution: Weigh 0.4394g of potassium hydrogen phosphate (reference reagent) that has been dried at 105-110℃ for 2h and cooled to room temperature in a desiccator, place it in a 200ml beaker, add appropriate amount of water to dissolve, transfer to a 1000ml volumetric flask, dilute to volume with water, and mix. This solution contains 0.1mg phosphorus per ml. 2.11 Phosphorus standard solution: Transfer 10.00ml of phosphorus standard stock solution (2.10) to a 1000ml volumetric flask, dilute to volume with water, and mix. This solution contains 0.001mg phosphorus per ml. 3 Instruments
Spectrophotometer.
4 Samples
4.1 The sample should pass through a 240 mesh.
4.2 The sample should be dried at 105±1℃+ for 2h and cooled to room temperature in a desiccator. Issued by the National Bureau of Standards on May 18, 1985
Implemented on March 1, 1986
5 Analysis steps
5.1 Determination quantity
GB 5195.7-85
When analyzing, a portion of the sample should be weighed for determination and the average value should be taken. 5.2 Sample quantity
Weigh 0.2000g of sample.
5.3 Blank test
Carry out a blank test with the sample.
5.4 Determination
5.4.1 Place the sample (5.2) in a 35ml polytetrafluoroethylene or platinum crucible. 5.4.2 Add 4ml hydrofluoric acid (2.3), dissolve and evaporate at low temperature and heat until it is close to 40°C, add 2ml hydrofluoric acid (2.3), continue to evaporate until it is close to dryness, and cool slightly.
5.4.3 Add 3ml hydrochloric acid (2.1) and 0.5ml hydrobromic acid (2.4), heat and evaporate until almost dry, cool slightly, add 2ml perchloric acid (2.5), heat and evaporate until almost dry, remove, and cool slightly. 5.4.4 Add 5.0ml hydrochloric acid (2.2), heat until the salts are dissolved, cool to room temperature, transfer to a 50ml volumetric bottle! Dilute with water to the mark and mix.
5.4.5 Take two portions of 20.00ml test solution (5.4.4), place them in 50ml volumetric flasks respectively, add 5.0ml hydrochloric acid (2.2) to each portion, one portion as the color developing solution and the other as the reference solution. 5.4.6 Colorimetric solution: Add 2 ml polyvinyl alcohol solution (2.7) and 3 ml mixed reducing agent (2.9), dilute with water to a volume of about 35 ml, mix well, add 4 ml ammonium molybdate solution (2.6) while shaking, rinse the bottleneck with water, add 5.0 ml rhodamine B (2.8), heat in a boiling water bath for 6 minutes, take out, cool to room temperature with running water, dilute with water to the scale, and mix well. Transfer to a 2 cm colorimetric IIIt. Use reference solution (5.4.7) as a reference and measure its absorbance at a wavelength of 585 nm on a spectrophotometer. Find the corresponding phosphorus amount from the working curve. 5.4.7 Reference solution: Follow 5.4.6, but do not add ammonium molybdate solution, but add 4 ml water instead. 5.5L Plotting of the curve
Pipette 0.000.50, 1.00, 2.00, 3.00, 4.00, 5.00 ml of phosphorus standard solution (2.11) and place them in 50 ml volumetric flasks respectively. Add 7.0 ml of hydrochloric acid (2.2). The following is carried out according to 5.4.6. Use the reagent blank (without adding phosphorus standard solution in this clause) as internal reference and measure its absorbance at a wavelength of 585 nm on a spectrophotometer. Plot the curve with phosphorus content as the horizontal axis and absorbance as the vertical axis. 6 Calculation of analysis results
Calculate the percentage of phosphorus according to the following formula:
Wherein: mi-
(ml=m2) Vα× 100
-phosphorus amount found on the working curve, g; phosphorus amount found on the bottom curve along with the sample as blank, g; total volume of test solution, ml;
volume of the solution taken, ml;
sample volume, g.
7 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. 16 yuan
Additional instructions:
0.0003~0.0005
0.0005~0.0010
0.0010~0.0030
0.0030~0.0050
GB5195.7—85
This standard is proposed by Zhongtun Nonferrous Metals Industry Corporation. This standard is drafted by Zhejiang Fluorite Mining Company. This standard is drafted by Zhejiang Metallurgical Research Institute.
The main drafters of this standard are Dong Lijuan and Wang Fengmei. From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB322-65 "Chemical Analysis Method of Fluorite" will be invalid. 16t
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