YS/T 273.12-2006 English PDF (YST273.12-2006)

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YS/T 273.12-2006: Chemical analysis methods and physical properties of cryolite. Part 12: The atomic absorption spectrophotometric method for the determination of calcium oxide content
YS/T 273.12-2006
YS
NONFERROUS METAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 71.100.10
H 21
Chemical analysis methods and physical properties of
cryolite - Part 12: The atomic absorption
spectrophotometric method for the determination of calcium
oxide content
ISSUED ON: MAY 25, 2006
IMPLEMENTED ON: DECEMBER 1, 2006
Issued by: National Development and Reform Commission of PRC
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Method summary ... 5
3 Reagents ... 5
4 Instruments and apparatuses ... 6
5 Test sample ... 6
6 Analytical procedure ... 7
7 Calculation of analysis result ... 8
8 Precision ... 8
9 Quality assurance and control ... 9
Chemical analysis methods and physical properties of
cryolite – Part 12: The atomic absorption
spectrophotometric method for the determination of calcium
oxide content
1 Scope
This Part specifies the method for determination of calcium oxide content in cryolite.
This Part applies to the determination of calcium oxide in cryolite. Determination range
(mass fraction): ≤1.25%.
2 Method summary
Use perchloric acid to de-fluorinate the test portion; heat until the smoke of perchloric
acid has evaporated, then use hydrochloric acid and water to dissolve it. In the presence
of lanthanum chloride, measure the calcium content using an air-acetylene fuel-rich
flame at the wavelength of 422.7 nm of the atomic absorption spectrometer.
3 Reagents
3.1 Perchloric acid (ρ1.67 g/mL).
3.2 Hydrochloric acid (1+1): guaranteed reagent.
3.3 Sodium solution (7.5 mg/mL): Transfer 9.5 g of high-purity sodium chloride and
use water to dissolve it in a 500 mL volumetric flask.
3.4 Sodium solution (1.5 mg/mL): Transfer 20 mL of sodium solution (3.3) into a 100
mL volumetric flask; use water to dilute to the mark; mix well.
3.5 Lanthanum chloride solution (200 g/L): Take 100 g of LaCl3·nH2O; use water to
dilute it in a 500 mL volumetric flask.
3.6 Aluminum solution (4 mg/mL): Weigh 4.00 g of pickled high-purity aluminum;
place it in a 500 mL beaker; cover the watch plate; add a total of 120 mL of hydrochloric
acid (3.2) in batches; add a drop of mercury to help dissolution; after the violent reaction
stops, slowly heat until it is completely dissolved; cool; transfer the solution to a 1 000
mL volumetric flask; use water to dilute to the mark; mix well.
3.7 Aluminum solution (0.8 mg/mL): Pipette 20 mL of aluminum solution (3.6) into a
100 mL volumetric flask; use water to dilute to the mark; mix well.
3.8 Calcium standard stock solution: Weigh 1.248 6 g of calcium carbonate that has
been previously dried at 105 °C; place it in a 250 mL beaker; cover it with a watch plate;
add 50 mL of water; then add 10 mL of hydrochloric acid (3.2); heat slightly; after the
reaction is complete, cool; transfer to a 500 mL volumetric flask; use water to dilute to
the mark; mix well. 1 mL of this solution contains 1.00 mg of calcium.
3.9 Calcium standard solution: Pipette 25.00 mL of calcium standard stock solution (3.8)
into a 500 mL volumetric flask; use water to dilute to the mark; mix well. 1 mL of this
solution contains 0.05 mg of calcium.
4 Instruments and apparatuses
Atomic absorption spectrometer, hollow cathode lamp with calcium.
Under the best working conditions of the instrument, anything that can achieve the
following indicators can be used:
- Characteristic concentration: In a solution consistent with the matrix of the
measured sample, the characteristic concentration of calcium shall not be greater
than 0.24 ug/mL.
- Precision: Use the standard solution of the highest concentration to measure the
absorbance for 10 times, where the standard deviation shall not exceed 1.0% of the
average absorbance. Use the standard solution of the lowest concentration (not the
“zero” concentration standard solution) to measure the absorbance for 10 times,
where the standard deviation shall not exceed 0.5% of the average absorbance of
the standard solution of the highest concentration.
- Linearity of working curve: Divide the working curve into five segments according
to the concentration, and the ratio of the absorbance difference of the highest
segment to the absorbance difference of the lowest segment shall not be less than
0.7.
5 Test sample
The test sample shall comply with the requirements of 3.3 in YS/T 273.13.