This standard specifies the determination of phosphorus content by molybdenum blue spectrophotometry. This standard is applicable to the determination of phosphorus content in limestone products for chemical use, with a determination range of 0.001% to 0.2%. GB/T 15057.9-1994 Determination of phosphorus content in limestone for chemical use by molybdenum blue spectrophotometry GB/T15057.9-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of phosphorus content in limestone for chemical industry
Molybdenum blue spectrophotometric method
Limestone for chemical industry-Determinatiom of phosphorus content---Molybdenum blue spectrophotometric method Subject content and scope of application
This standard specifies the determination of phosphorus content by molybdenum blue spectrophotometric method. GB/T 15057.9---94
This standard is applicable to the determination of phosphorus content in limestone products for chemical industry, with a determination range of 0.001% to 0.2%. 2 Reference standards
GB6682 Specifications and test methods for water used in analytical laboratories GB/T9721 General rules for molecular absorption spectrophotometry of chemical reagents (ultraviolet and visible light parts) 3 Summary of the method
The sample is decomposed with nitric acid and perchloric acid, and the generated phosphomolybdic heteropoly acid is reduced to phosphomolybdic blue in a hydrochloric acid medium with ascorbic acid as a reducing agent. Measure the absorbance at a wavelength of 680 or 780 mm on a spectrophotometer. 4 Reagents and solutions
The water used in this standard shall comply with the specifications of Grade III water in GB6682. The listed reagents, unless otherwise specified, are analytically pure reagents. 4.1 Nitric acid (GB 626).
4.2 Perfluoric acid (GB623).
4.3 Aminobromic acid (GB 621).
4.4 Hydrochloric acid (GB622): 1+2 solution.
4.5 Hydrochloric acid: 1+6 solution.
4.6 Sodium hydroxide (GB629): 200 g/L bath solution. 4.7 Ammonium hydroxide E(NH)MoOz-4HzO (GB657): 20 g/L solution. 4.8 Ascorbic acid: 20 g/L solution (prepare before use). ：4.9 Phosphorus standard solution: 100μg/mL. Weigh 0.4394g potassium dihydrogen phosphate (high purity reagent) that has been dried at 105℃ and cooled to room temperature and place it in a 100mL beaker. Dissolve it in water and transfer it to a 1000mL volumetric flask. Add water to the mark and shake well. This solution contains 100gg phosphorus in 1mL.
4.10 Phosphorus standard solution: 10ug/mL. Take 50.00ml. Phosphorus standard solution (4.9), place it in a 500mL volumetric flask, dilute it to the mark with water and shake well. This solution contains 10μg phosphorus in 1mL. 4.11 p-Nitrophenol catalyst: 2/L ethanol (GB679) solution. Approved by the State Administration of Technical Supervision on May 5, 1994. Implementation on February 1, 1995. 5. Instruments. GB/T 15057.9-94. Spectrophotometer: It should comply with the provisions of GB/T9721. 6. Samples. Laboratory samples should pass through a 125um test sieve (GB6003), dry at 105-110℃ for more than 2h, and cool to room temperature in a desiccator. 7. Analysis steps. 7.1 Weigh about 1g of sample to an accuracy of 0.0001g and place it in a 150mL beaker. Perform a blank test at the same time. 7.2 Moisten and shake with a little water. Cover the surface blood and slowly add 8mL of nitric acid (4.1) along the mouth of the beaker. After the violent reaction stops, rinse the watch glass and the beaker wall with water. Then add 5mL perchloric acid (4.2) and 1mL hydrobromic acid (4.3). Note: For samples without arsenic, it is not necessary to add hydrobromic acid. 7.3 Cover the surface blood and remove a part of it. Heat and evaporate it on a low-temperature electric hot plate until white perchloric acid smoke is emitted, until about 1mL of the solution is left, remove it and cool it.
Note: It cannot be evaporated to dryness to avoid the formation of calcium phosphate precipitation. 7.4 Rinse the surface blood and the wall of the beaker with hot water to a volume of 15~30mL, heat to dissolve the salts, remove it and cool it. Transfer it to the corresponding volumetric flask as specified in Table 1, dilute it to the scale with water, and shake it well. 7.5 Dry filter it with medium-speed filter paper. Pipette the test solution as specified in Table 1 and place it in a 50mL volumetric flask. Table 1
Phosphorus content, %
0.001~0.010
>0. 01 ~0. 05
>0. 05~0. 10
>0.10~0.20
Volume of dilution flask, mLwwW.bzxz.Net
Volume of test solution absorbed, mL
Absorption cell, cm
Measurement wavelength, nm
7.6Add water to 20mL, add 1 drop of p-nitrophenol indicator solution (4.11), and use sodium hydroxide solution (4.6) and hydrochloric acid solution (4.5) to adjust the solution from yellow to colorless. Add 6.0mL hydrochloric acid solution (4.4), 4.0mL ammonium molybdate solution (4.7), and 2.0mL ascorbic acid solution (4.8) (shake well after adding each reagent). Rinse the bottleneck of the volume with a small amount of water, place it in a boiling water bath and heat it for 5 minutes, remove it, and cool it to room temperature with running water. Dilute it with water to the scale and shake it well.
7.7 Select the corresponding absorption cell and wavelength according to Table 1, use the blank test solution as a reference, and measure the absorbance on the spectrophotometer. 8 Drawing of the working curve
Measure 0.00, 1.00, 1.50, 2.00, 4.00, 6.008.00, 10.00mL of phosphorus standard solution (4.10) and place them in a group of 50mL volumetric flasks respectively. The following steps are carried out according to 7.6 and 7.7, in which the reagent blank is used as a reference to measure the absorbance. Draw the working curve with the phosphorus amount as the horizontal axis and the corresponding absorbance as the vertical axis. Note: The range of the working curve should be selected according to the phosphorus content in the sample. 9Description of analysis results
The phosphorus (P) content (α) expressed as a mass percentage is calculated as follows:210
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Wherein: m-
GB/T15057.9-94
mi×10-6
The phosphorus content found from the working curve, ug; V, the volume of the sample solution absorbed, mL,
VThe total volume of the sample solution, mL;
m——The mass of the sample, g.
10Allowance difference
The arithmetic mean of the parallel analysis results is taken as the final analysis result. The absolute difference of the parallel analysis results should not be greater than the allowable difference listed in Table 2.
Additional Notes:
Phosphorus (P) content
0. 001 0~ 0. 005 0
>0. 005 0~ 0. 020 0
>0. 020~0. 070
>0. 070~0. 200
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. Table 2
This standard was drafted by the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Wang Heping and Li Donghao. Allowed to raise
This standard refers to the Japanese Industrial Standard JISM8850-1982 "Limestone Analysis Method". Standard Authorization Search Network A
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