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

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YS/T 273.5-2006: Chemical analysis methods and physical properties of cryolite. Part 5: Determination of sodium by flame atomic absorption spectrometric method
YS/T 273.5-2006
YS
NONFERROUS METAL INDUSTRY STANDARD
OF THE PEOPLE'S REPUBLIC OF CHINA
ICS 71.100.10
H 21
Replacing YS/T 273.5-1994
Chemical analysis methods and physical properties of
cryolite - Part 5: Determination of sodium by flame atomic
absorption spectrometric method
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 Apparatus ... 5
5 Sample ... 6
6 Analysis procedure ... 6
7 Calculation of analysis results ... 7
8 Precision ... 8
9 Quality assurance and control ... 8
Foreword
YS/T 273 "Chemical analysis methods and physical properties of cryolite" is divided
into 13 parts:
-- Part 1: Determination of moisture content - Gravimetric method;
-- Part 2: Determination of ignition loss;
-- Part 3: Determination of fluoride content;
-- Part 4: Determination of aluminum content - EDTA titration method;
-- Part 5: Determination of sodium by flame atomic absorption spectrometric
method;
-- Part 6: Determination of silica content by the molybdenum blue photometric;
-- Part 7: Determination of iron content by orthophenantholine photometric method;
-- Part 8: Determination of sulfate content - Barium sulfate gravimetric method;
-- Part 9: Determination of phosphorus pentoxide content - Molybdenum blue
photometric method;
-- Part 10: Determination of alumina content by gravimetric method;
-- Part 11: Determination of sulphur content by X-ray fluorescence spectrometric
method;
-- Part 12: The atomic absorption spectrophotometric method for the determination
of calcium oxide content;
-- Part 13: Preparation and storage of test samples.
This Part is Part 5.
This part is a revision of YS/T 273.5-1994. In addition to editorial modification, two
chapters on Precision AND Quality Assurance and Control have been added. Other
changes include:
-- The measuring wavelength of the instrument is changed from the most sensitive
589.0 nm to the hypo-sensitive 589.6 nm;
-- The length of the working curve is shortened, and the concentration of the highest
concentration standard solution in the working curve is reduced from 10.0
μg/mL to 5.00 μg/mL;
Chemical analysis methods and physical properties of
cryolite - Part 5: Determination of sodium by flame atomic
absorption spectrometric method
1 Scope
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 (ρ 1.84 g/mL).
3.2 Hydrochloric acid (ρ 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.
-- Characteristic concentration: In a solution consistent with the matrix of the
measured sample, the characteristic concentration of sodium shall not be greater
than 0.07 ug/mL.
-- Precision: Use the standard solution with the highest concentration to measure
the absorbance 10 times, and the standard deviation shall not exceed 1.0% of
the average absorbance; use the standard solution with the lowest concentration
(not the "zero" concentration standard solution) to measure the absorbance 10
times, and the standard deviation shall not exceed 0.5% of the average
absorbance of the highest concentration standard solution.
-- Working curve linearity: Divide the working curve into 5 equal segments
according to concentration, and the ratio of the absorbance difference in the
highest segment to the absorbance difference in the lowest segment is not less
than 0.85.
5 Sample
The sample shall comply with the requirements of 3.3 in YS/T 273.13.
6 Analysis procedure
6.1 Test portion
Weigh 0.5 g of test sample (5), accurate to 0.0001 g.
6.2 Number of determinations
Two determinations shall be carried out independently and the average value shall be
taken.
6.3 Blank test
Do a blank test along with the sample test.
6.4 Determination
6.4.1 Place the test portion (6.1) in the platinum dish (4.1), add 5 mL of sulfuric acid
(3.1), and slowly dissolve it in a sand bath (15 min~20 min) to remove fluorine; then,
heat it to evaporate until the thick smoke emits; remove the test portion and cool it to
room temperature; add 3 mL of hydrochloric acid (3.2) and 30 mL of water, and heat in
a low-temperature sand bath until all salts are dissolved. After cooling, transfer the
solution to a 500 mL volumetric flask, dilute to volume with water, and mix well.
6.4.2 According to Table 1, take the test solution (6.4.1), place it in a 500 mL volumetric