UDC 669.14/.15.543.06.
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
中華人民共和國(guó)國(guó)家標(biāo)準(zhǔn)
GB 223.54-87
Methods for Chemical Analysis of Iron, Steel and Alloy
the Flame Atomic Absorption Spectrophotometric Method for the Determination of Nickel Content
鋼鐵及合金化學(xué)分析方法
火焰原子吸收分光光度法測(cè)定鎳量
Issued on: April 3, 1987 Implemented on: March 1, 1988
Issued by the Ministry of Metallurgical Industry
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
中華人民共和國(guó)國(guó)家標(biāo)準(zhǔn)
GB 223.53-87
Methods for Chemical Analysis of Iron, Steel and Alloy
the Flame Atomic Absorption Spectrophotometric Method for the Determination of Nickel Content
鋼鐵及合金化學(xué)分析方法
火焰原子吸收分光光度法測(cè)定鎳量
This Standard is applicable to the determination of nickel content in cast iron, carbon steel and low alloy steel. The determination range: 0.005~0.50%.
This Standard complies with "General Rules and Regulations of the Chemical Analysis Methods for Products of Metallurgical Industries" (GB 1467-78).
1 Principle
Decompose the test sample with suitable mixed acid; add perchloric acid; evaporate to smoke; dissolve the salt with water; spray the sample solution into air-acetylene flame; take nickel hollow cathode lamp as light source; measure the absorbance at 232.0 nm wavelength of atomic absorption spectrophotometer.
In order to eliminate the effects of matrix, iron with the same quantity as that of the sample solution shall be added when plotting the calibration graph.
2 Reagents
2.1 Perchloric acid (ρ 1.67g/ml).
2.2 Mixed acid of hydrochloric acid-nitric acid: mix one portion of hydrochloric acid (ρ 1.19g/ml), one portion of nitric acid (ρ 1.42g/ml) and two portion of water. Prepare just before use.
2.3 Mixed acid of nitric acid-perchloric acid: mix 100ml of nitric acid (ρ1.42 g/ml) and 800ml of perchloric acid (2.1), dilute to 1L with water and mix.
2.4 Pure iron solution: weigh 10g of pure iron (nickel content < 0.0005 %); place in a 800 ml beaker; add 100ml of mixed acid (2.2) of hydrochloric acid-nitric acid; heat to complete dissolution; add 120 ml of perchloric acid (2.1); evaporate to white smoke of perchloric acid occur and maintain for 1min; cool down; add 100ml of water; heat to dissolve the salt; cool down and transfer to a 250ml volumetric flask; dilute to the mark with water and mix.
2.5 Nickel standard solution
2.5.1 Weigh 1.0000g of metallic nickel (> 99.9 %); place in a 250ml beaker; add 50ml of nitric acid (1+1); heat to dissolve; cool down to room temperature; transfer in a 1000ml volumetric flask; dilute to the mark with water and mix; 1ml of this solution contains 1.0 mg of nickel.
2.5.2 Take 10.00 ml of nickel standard solution (2.5.1); place in a 100ml volumetric flask; dilute to the mark with water and mix; 1ml of this solution contains 100 μg of nickel.
3 Apparatus
Atomic absorption spectrophotometer, equipped with an air-acetylene burner and a nickel hollow cathode lamp; air-acetylene shall be pure enough (free of water, oil and nickel) to give a steady clear fuel-lean flame.
The atomic fluorescence spectrophotometer used shall reach the following indexes:
3.1 Minimum requirements on precision: absorbance shall be measured with the calibration solution of maximum concentration for ten times, and the standard deviation shall not exceed 1.0% of the mean absorbance.
Measure the absorbance for 10 times with the calibration solution of the minimum concentration (not the zero calibration solution), and the standard deviation adopted shall not exceed 0.5 % the mean absorbance of the calibration solution of the maximum concentration.
3.2 Characteristic concentration: the characteristic concentration of nickel shall be less than 0.10 μg nickel/ml (wavelength 232.0 nm) in the solution with the same matrix as the sample solution for final measurement.
3.3 Detection limit: the detection limit of nickel shall be less than 0.15 μg nickel/ml (wavelength 232.0 nm) in the solution with the same matrix as the sample solution for final measurement.
3.4 Linear of calibration graph: the ratio of the slope (expressed as variable quantity) of upper part of calibration graph within the range of 20 % concentration to the slope of lower part of calibration graph within the range of 20 % concentration shall not be less than 0.7.
4 Analytical Procedures
4.1 Sample mass
Weigh 1.0000 g of test sample.
4.2 Blank test
Carry out blank tests along with the tests on test samples.
4.3 Determination
4.3.1 Place the sample (4.1) in a 400ml beaker; add 15 ml of mixed acid (2.3) of nitric acid-perchloric acid; cover with a watch glass; heat at low temperature to dissolve; evaporate until white smoke of perchloric acid occur and maintain for 1 min; cool down; add 15 ml of water; dissolve the salts at subfebrile temperature; cool down to room temperature; transfer into a 100ml volumetric flask; dilute to the mark with water and mix. In case such precipitates as graphite, silicic acid, tungstic acid, etc. separate out from test solution, dry filtering must be conducted.
Note: (1) as for the test sample difficult to dissolve in mixed acid (2.3) of nitric acid-perchloric acid, mixed acid (2.2) of hydrochloric acid-nitric acid may be adopted for dissolving; then add 12 ml of perchloric acid (2.1); evaporate to smoke and maintain for 1 min; the rest operations shall be conducted according to the corresponding procedures specified in (4.3.1).
(2) if the nickel content in the sample solution exceeds 1.0 %, the sample solution shall be diluted: take 20ml of sample solution (4.3.1), place in a 100ml volumetric flask; dilute to the mark with water and mix. Dilute the blank solution with the same procedures.
4.3.2 Set the air-acetylene flame to zero with water and measure the absorbance of the sample solution at 232.0 nm wavelength on atomic absorption spectrophotometer; find out the nickel concentration (μg/ml) on the calibration graph according to the absorbance of the sample solution and the absorbance of the accompanied test sample blank solution.
4.4 Plotting the calibration graph
4.4.1 Nickel content < 0.10%
Add 25ml of pure iron solution (2.4) into eight 100ml volumetric flasks respectively; then add 0.00 ml, 0.50 ml, 1.00 ml, 2.00 ml, 4.00 ml, 6.00 ml, 8.00 ml and 10.00 ml of nickel standard solution (2.5.2) respectively; dilute to the mark with water and mix.
4.4.2 Nickel content: 0.10~0.50 %
Add 5ml of pure iron solution (2.4) into seven 100ml volumetric flasks respectively; then add 0.00 ml, 1.00 ml, 2.00 ml, 4.00 ml, 6.00 ml, 8.00 ml and 10.00 ml of nickel standard solution (2.5.1) respectively; dilute to the mark with water and mix.
4.4.3 Set the air-acetylene flame to zero with water and measure the absorbance of solution (4.4.1) or solution (4.4.2) at 232.0 nm wavelength on the atomic absorption spectrophotometer.
The net absorbance of solution in nickel calibration graph series may be obtained by subducting the absorbance of solution with 0 in concentration from the absorbance of each solution in calibration graph series; plot the calibration graph by taking the nickel concentration as the lateral coordinates and the net absorbance as the vertical coordinates.
5 Calculation of Analysis Results
Percentage content of nickel shall be calculated according to the following formula:
Ni (%) = ×100
Where,
C2—Nickel concentration of the sample solution found on the calibration graph, μg/ml;
C1—Nickel concentration of the accompanied test sample blank solution found on the calibration graph, μg/ml;
f—Dilution ratio. In case the nickel content is less than or equal to 0.10 %, adopt f=1; in case the nickel content is greater than 0.1 %, adopt f=5;
V—Volume of tested sample solution, ml;
m—Sample mass, g.
6 Precision
Precision Table
Level (%) (m/m) Repeatability (r) Reproducibility (R)
0.005~0.50 lgr =-1.5732+0.6021lgm lgR=-1.1569+0.6799lgm
Repeatability is the maximum difference value of the two independent test results for the same sample with the same apparatus by the same operator in the same laboratory with normal and correct operation of this method at a probability of 95%.
Reproducibility refers to the maximum difference value of two independent results of single tests carried out at a probability of 95% with this method and normal and proper operation by two operators in different laboratories for the identical samples.
If the difference between the results obtained from the two independent tests exceeds the corresponding repeatability and reproducibility values, the two results are considered as suspicious.
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Additional Explanations:
This Standard was proposed by the Ministry of Metallurgical Industry.
This Standard is under the jurisdiction of Technology Department of Central Iron and Steel Research Institute, Ministry of Metallurgical Industry.
Central Iron and Steel Research Institute, Ministry of Metallurgical Industry is responsible for the drafting of the Standard.
This Standard was drafted by Central Iron and Steel Research Institute.
Chief drafting staff of this Standard: Xie Ronghou and Xing Rugang.
Level mark of this Standard is as GB 223.54-87 I.
