GB/T 14501.4-1993 Determination of silicon in uranium hexafluoride - Spectrophotometric method
Some standard content:
National Standard of the People's Republic of China
Determination of silicon in uranium hexafluoride
Spectrophotometric method
Spectrophotometric determination of silicon in uranium hexafluoride1 Subject content and scope of application
GB/T14501.4--93
This standard specifies the method principle, instrument, reagent, analysis steps, result calculation and method precision for the spectrophotometric determination of silicon in uranium hexafluoride. bzxz.net
This standard is applicable to the determination of silicon in uranium hexafluoride. When the sample volume is 0.7g of uranium hexafluoride hydrolyzate, the determination range is 4-20pg/g uranium.
2g of tungsten and 50ug of tungsten do not interfere with the determination of silicon. The interference of phosphorus is eliminated with oxalic acid; the interference of fluorine is eliminated with boric acid. 2 Principle of the method
Within a certain acidity range, ammonium molybdate and silicate form silico-molybdenum complex ions, which are reduced to silico-molybdenum blue complexes by a mixture of 1-amino-2-naphthalene-4-sulfonic acid, sodium sulfite, and sodium metabisulfite, and spectrophotometric determination is performed at a wavelength of 710 nm. 3 Instruments and equipment
3.1 Polyethylene bottle: 100 mL, with scale. 3.2 Polyethylene cup, 250 mL.
3.3 Polyethylene pipettes: 1, 2, and 5 mL, qualified by metrological identification. 3.4 Porous water bath.
3.5 Platinum III: 100 mL.
3.6 Platinum crucible: 50 mL.
3.7 Analytical balance: sensitivity 0.1 mg.
3.8 Spectrophotometer: with 5 cm colorimetric. 4 Reagents
Unless otherwise specified, all reagents used are high-grade pure reagents, and all analytical water is deionized water (resistivity greater than 2×10°0cm). 4.1 Ammonium hydroxide: Purified. Distill 500mL of ammonium hydroxide (25%28%, analytical grade) into 300mL of water in a plastic bottle with a branch tube, and determine its concentration
4.2 Ammonium hydroxide solution: Prepare with ammonium hydroxide (4.1), c(NH,OH)=8mol/L. 4.3 Ammonium molybdate solution: 100g/L. Dissolve 100g of ammonium molybdate [(NH). MoO2:4H,0, analytical grade) in 500mL of hot water (water temperature not exceeding 60℃), and dilute to 1L with water. 4.4 Boric acid solution: 50g/L. Dissolve 25g of boric acid (HBO,) in water, and dilute to 500mL with water. 4.5 Oxalic acid solution: 50g/L. Dissolve 25g oxalic acid (H, C.02H,0) in water, dilute to 500mL with water4.6 Hydrochloric acid solution: c(HCI) = 6mol/L. 4.7 Hydrochloric acid solution: c(HCI) = 1mol/L. Approved by the State Bureau of Technical Supervision on June 19, 1993, implemented on April 1, 1994
GB/T14501.4-93
4.8 Sulfuric acid solution: c(1/2H,SO) = 6mol/L. 4.9 Sulfuric acid solution: c(1/2H,SO,) = 18mol/L4.10 Mixed reduction solution: Dissolve 0.1g 1-amino-2-naphthol-4-sulfonic acid (analytical grade), 1.0g sodium sulfite (Na2SO3. analytical grade), 10.0g sodium metabisulfite (NazS.Os, analytical grade) in water, dilute to 100mL with water. Note: All reagent solutions are stored in plastic bottles. All plastic bottles are added with 20-30 mL of 1+1 hydrofluoric acid and placed in a boiling water bath to heat and remove silicon, and then cleaned with water.
4.11 Silicon standard solution: Accurately weigh 0.2674 g of silicon dioxide (99.99%) in platinum (3.6), add 2.5 g of anhydrous sodium carbonate, mix well, cover with platinum, put in a muffle furnace and heat to 950°C, keep constant temperature for 20 minutes, take out, cool and leach with hot water. The leachate is transferred to a 500 mL volumetric flask, diluted with water to the scale, shake well, and transferred to a dry polyethylene bottle. Transfer 10.0 mL of the above solution to a 1 L volumetric flask, dilute with water to the scale, shake well, and store in a dry polyethylene bottle. This solution contains 2.5 μg of silicon in 1 mL. Note: The silicon contained in the silicon solution stored in the polyethylene bottle is unstable, and a new silicon standard solution should be prepared every month. 5 Analysis steps
5.1 Draw a standard curve
5.1.1 Add silicon standard solution (4.11) with silicon content of 0, 2.5, 5.07.5, 10.0, and 12.5 μg to six polyethylene bottles (3.1) respectively.
5.1.2 Add 1.2 mL of sulfuric acid solution (4.9) and dilute to 25 mL with water. 5.1.3 Place the polyethylene bottle in a water bath and heat to 75-80°C. 5.1.4 Remove the polyethylene bottle from the water bath and immediately add 6 mL of ammonium molybdate solution (4.3), add 0.5 mL of hydrochloric acid solution (4.6), shake well, and let stand for 10 minutes.
5.1.5 Add 10 mL of oxalic acid solution (4.5), stir well, and let stand for 2 minutes. 5.1.6 Add 2 mL of mixed reducing solution (4.10), shake well, add 3.5 mL of hydrochloric acid solution (4.6), shake well. 5.1.7 Transfer the solution to a 50 mL volumetric flask, dilute to the mark with hydrochloric acid solution (4.7), shake well. 5.1.8 Transfer part of the solution to a 5 cm cuvette, measure the absorbance at a wavelength of 710 nm using the reagent blank solution as a reference. 5.1.9 Draw a standard curve based on the amount of silicon versus the corresponding absorbance. 5.2 Sample analysis
5.2.1 Weigh 30 g of uranium hexafluoride and place it in a polyethylene cup (3.2) and hydrolyze it with 80 mL of water. 5.2.2 Transfer the uranium hexafluoride hydrolyzate to a polyethylene bottle (3.1), dilute to 100 mL with water, and calibrate the uranium concentration. 5.2.3 Use a polyethylene pipette to transfer 0.7 g of uranium hexafluoride hydrolyzate into a polyethylene bottle (3.1), add 1 mL of sulfuric acid (4.8) and 20 mL of boric acid solution (4.4) and shake well. At the same time, add 1 mL of sulfuric acid solution (4.8) and 20 mL of boric acid solution (4.4) into another polyethylene bottle as a reagent blank solution.
5.2.4 Place the sample solution and reagent blank solution in a water bath at 70-75°C and heat for 20 min. 5.2.5 Remove the polyethylene bottle from the water bath, add 1.2 mL of sulfuric acid solution (4.9), and dilute the solution to 25 mL with water. 5.2.6 Place the polyethylene bottle in a water bath and heat to 75-80°C. 5.2.7 Remove the polyethylene bottle from the water bath and immediately add 6 mL of ammonium molybdate solution (4.3). 5.2.8 Use a vinyl pipette to add 1.5mL and 1.0mL of ammonium hydroxide solution (4.2) to the sample solution and reagent blank solution respectively, shake well, and let stand for 10 minutes. The following operations are carried out according to 5.1.5 to 5.1.8. 5.2.9 Calculate the silicon content from the standard curve based on the measured absorbance. 6 Calculate the results of the analysis according to the following formula:
GB/T14501.4-93
Wherein, C——Silicon content in uranium hexafluoride sample, ug/g uranium; M——Silicon content found from the standard curve, ugC, —Concentration of sodium hexafluoride in hydrolyzate, g/mL; V is the volume of sodium hexafluoride hydrolyzate taken, mL. 7 Precision
When the confidence level is 95%, the relative standard deviation of 10pg silicon is ±8%. Additional remarks:
This standard is proposed by China National Nuclear Corporation. This standard was drafted by the State-owned August 14 Factory. The main drafters of this standard are Deng Zaocheng, Yu Shuyun and Xiao Zhengyi. This standard is equivalent to the American Society for Testing and Materials standard ASTMC761-88 "Standard Analysis Method for Uranium Hexafluoride". 17
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