YS/T 273.5-2006 English PDF (YST273.5-2006)

This Part specifies the method for the determination of sodium content in cryolite. This Part applies to the determination of sodium content in cryolite. Determination range: 20%~35%. 2 Method summary After the test portion is dissolved with sulfuric acid, it is heated to remove fluorine, and the precipitate is dissolved with hydrochloric acid and water; the sodium content of the test solution is determined at the wavelength of 589.0 nm or 589.6 nm of an atomic absorption spectrometer by the use of an air-acetylene fuel-lean flame. 3 Reagents 3.1 Sulfuric acid (?? 1.84 g/mL). 3.2 Hydrochloric acid (?? 1.19 g/mL). 3.3 Sodium standard solution: Weigh 3.089 g of anhydrous sodium sulfate that has been dried at 120 ??C and cooled in a desiccator, place it in a 250 mL beaker, and add 100 mL of water to dissolve; then, add 10 mL of hydrochloric acid (3.2), transfer the solution to a 1000 mL volumetric flask, dilute to volume with water, mix well, and transfer it to a polyethylene bottle. 1 mL of this solution contains 1.000 mg of sodium. 4 Apparatus 4.1 Platinum dish: The diameter is 80 mm, and the height is 35 mm. 4.2 Atomic absorption spectrometer: It is equipped with a sodium hollow cathode lamp. Any instrument that can meet the following indicators under the best working conditions can be used. YS/T 273.5-2006 www.ChineseStandard.net ? Buy True-PDF ? A and quot;delivery Page 6 of 8 -- Characteristic concentration: In a solution consistent with the matrix of the measured sample, the characteristic concentration of sodium shall not be