GB/T 20975.9-2020Methods for chemical analysis of aluminium and aluminium alloys—Part 9:Determination of lithium content—Flame atomic absorption spectrometry (English PDF)

Foreword

GB/T 20975 "Methods for Chemical Analysis of Aluminum and Aluminum Alloys" is divided into 37 parts.

---Part 1: Determination of mercury content;

---Part 2: Determination of arsenic content;

---Part 3: Determination of copper content;

---Part 4: Determination of iron content;

---Part 5: Determination of silicon content;

---Part 6: Determination of cadmium content;

---Part 7: Determination of manganese content;

---Part 8: Determination of zinc content;

---Part 9: Determination of lithium content by flame atomic absorption spectrometry;

---Part 10: Determination of tin content;

---Part 11: Determination of lead content;

---Part 12: Determination of titanium content;

---Part 13: Determination of vanadium content;

---Part 14: Determination of nickel content;

---Part 15: Determination of boron content;

---Part 16: Determination of magnesium content;

---Part 17: Determination of strontium content;

---Part 18: Determination of chromium content;

---Part 19: Determination of Zirconium Content;

---Part 20: Determination of Gallium Content Butyl Rhodamine B Spectrophotometry;

---Part 21: Determination of calcium content;

---Part 22: Determination of beryllium content;

---Part 23: Determination of antimony content;

---Part 24: Determination of total rare earth content;

---Part 25: Determination of element content by inductively coupled plasma atomic emission spectrometry;

---Part 26: Determination of carbon content by infrared absorption method;

---Part 27: Determination of cerium, lanthanum and scandium content by inductively coupled plasma atomic emission spectrometry;

---Part 28: Determination of cobalt content by flame atomic absorption spectrometry;

---Part 29: Determination of molybdenum content thiocyanate spectrophotometric method;

---Part 30: Determination of hydrogen content by heating extraction thermal conductivity method;

---Part 31: Determination of phosphorus content molybdenum blue spectrophotometric method;

---Part 32: Determination of Bismuth Content;

---Part 33: Determination of potassium content by flame atomic absorption spectrometry;

---Part 34: Determination of sodium content by flame atomic absorption spectrometry;

---Part 35: Determination of Tungsten Content Thiocyanate Spectrophotometric Method;

---Part 36: Determination of silver content by flame atomic absorption spectrometry;

--- Part 37: Determination of Niobium Content.

This part is Part 9 of GB/T 20975.

This section was drafted in accordance with the rules given in GB/T 1.1-2009.

This part replaces GB/T 20975.9-2008 "Methods for Chemical Analysis of Aluminum and Aluminum Alloys Part 9: Determination of Lithium Content Flame Origin Compared with GB/T 20975.9-2008, the main technical changes except for editorial changes are as follows.

--- Added standard use safety warnings;

---Modified the measurement range from 0.002%~3.00% to 0.0020%~12.00% (see Chapter 1, 2008 edition Chapter 1);

--- Added "Normative Reference Documents" (see Chapter 2);

--- Added "Terms and Definitions" (see Chapter 3);

---Added the requirements for reagents and water used in analysis (see Chapter 5);

---Modified the sample solution preparation steps (see 8.4.3, 6.4.3 of the 2008 edition);

---Modified the preparation steps of the standard curve (see 8.5.1, 6.5.1 of the 2008 edition);

---Modified "Precision" (see Chapter 10, Chapter 8 of the 2008 edition);

--- Deleted "quality control and assurance" (see Chapter 9 of the 2008 edition);

--- Added "Test Report" (see Chapter 11).

1 Scope

This part of GB/T 20975 specifies the flame atomic absorption spectrometry to determine the lithium content in aluminum and aluminum alloys.

This section applies to the arbitration determination of lithium content in aluminum and aluminum alloys, the measurement range. 0.0020% to 12.00%.

2 Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this document. For undated references, the latest version (including all amendments) applies to this document.

GB/T 8005.2 Terminology of Aluminum and Aluminum Alloy Part 2: Chemical Analysis

GB/T 8170-2008 Numerical rounding rules and the expression and determination of limit values

3 Terms and definitions

The terms and definitions defined in GB/T 8005.2 apply to this document.

4 Method summary

The sample is dissolved in hydrochloric acid, hydrogen peroxide and nitric acid, at a wavelength of 670.8nm in a flame atomic absorption spectrometer, with air-acetylene lean The flame measures the absorbance of lithium to determine the lithium content.

5 Reagents

Unless otherwise stated, only reagents and laboratory secondary water confirmed to be analytically pure are used in the analysis.

5.1 Pure aluminum (wAl>=99.99%, wLi<=0.0005%).

5.2 Nitric acid (rho=1.42g/mL).

5.3 Hydrofluoric acid (rho=1.14g/mL).

5.4 Hydrogen peroxide (rho=1.10g/mL).

5.5 Hydrochloric acid (1 1).

5.6 Nitric acid (1 9).

5.7 Sulfuric acid (1 1).

5.8 Aluminum solution A (20mg/mL). Weigh 20.00g pure aluminum (5.1) into a 1000mL beaker, and add a total of 600mL salt in batches Acid (5.5), cover with a watch glass, after the violent reaction stops, add a few drops of hydrogen peroxide (5.4), slowly heat until completely dissolved, and steam until the salt is out Now, cool slightly, add 600mL nitric acid (5.6), heat until the salt is completely dissolved, and cool to room temperature. Transfer the solution into a 1000mL volumetric flask, Dilute to the mark with water and mix well.

5.9 Aluminum solution B (1mg/mL). Pipette 25.0mL aluminum solution A (5.8) in a 500mL volumetric flask, dilute to the mark with water, and mix.

5.10 Lithium standard storage solution. use a certified standard solution for preparation first. Or weigh 5.3228g lithium carbonate [w(Li2CO3)>=99.99%] In a 500mL beaker, cover with a watch glass, slowly add 125mL nitric acid (5.6), heat until completely dissolved, boil for a few minutes, and cool to room temperature. Transfer the solution to a 1000mL volumetric flask, dilute to the mark with water, and mix. This solution 1mL contains 1.0mg lithium.

5.11 Lithium standard solution. Pipette 10.00mL lithium standard stock solution (5.10) into a 1000mL volumetric flask, dilute to the mark with water, and mix. uniform. This solution 1mL contains 10µg lithium.

6 Instruments

Atomic absorption spectrometer with lithium hollow cathode lamp. The instrument should meet the following conditions.

---Characteristic concentration. In a solution consistent with the matrix of the measurement sample solution, the characteristic concentration of lithium should not be greater than 0.018µg/mL;

---Precision. Use the highest concentration of standard solution to measure the absorbance 10 times, and the standard deviation should not exceed 1.0% of the average absorbance; Use the lowest concentration standard solution (not the "zero" concentration solution) to measure the absorbance 10 times, and the standard deviation should not exceed the highest concentration 0.5% of the average absorbance of the standard solution;

---Linear working curve. Divide the working curve into five equal sections according to the concentration, the difference between the absorbance difference of the highest section and the absorbance difference of the lowest section The ratio should not be less than 0.70.

7 Sample

Process the sample into chips with a thickness of not more than 1mm.

8 Analysis steps

9 Test data processing

The lithium content is calculated as the lithium mass fraction wLi, calculated according to formula (1).

When the lithium mass fraction is less than 1.00%, the calculation result retains two significant digits; when the lithium mass fraction is >=1.00%, the calculation result is expressed to the smallest Count the last two digits. The rounding of values shall be implemented in 3.2 and 3.3 of GB/T 8170-2008.

10 Precision

11 Test report

The test report should give at least the following aspects.

a) Number and name of this part;

b) All necessary information about identification of samples, laboratory, analysis date, report date, etc.;

c) Express the test results in an appropriate form;

d) Abnormal phenomena during the test;

e) Signatures of review and approval personnel.