GB/T 4333.8-1988 Chemical analysis method for ferrosilicon - Determination of calcium content by atomic absorption spectrometry GB/T4333.8-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of ferrosilicon
Determination of calcium content by atomic absorption spectrometry
Methods far chcmical analysis of ferrosiliconThe atornic absorption spectrometric mcthodfor the determininalion of calcium cnntent1Subject content and scope of application
This standard specifies the determination of calcium content by atomic absorption spectrometry. This standard also uses the following determination range of calcium content in ferrosilicon: 0.050%--1.80%. 2 Method Summary
UDC. 669. 15 782
:543.42:546
GB 4333. 8
Recommendation GB4333.884
The sample is decomposed with nitric acid and hydrofluoric acid, and perchloric acid is evaporated with fuming. Lanthanum salt is used as a release agent in a hydrochloric acid medium, and the absorbance of calcium is measured at a wavelength of 422.7nm on an atomic absorption spectrometer with air-acetylene flame. 3 Reagents
3.1 Hydrochloric acid (pl.4? g/mL).
3.2 Hydrofluoric acid (pl.15g/mL)
3.3 Homulic acid (pl.67g/mL)
3.4 ​​Acid (1:—4).
3.5 Hydrochloric acid (1|99)
3.6 Ascorbic acid solution (25g/1.)
3.7 Solution: Weigh 10g of iron oxide (99.99%), put it in a 250mL beaker, add 100ml of water and 10ml of hydrochloric acid (pl.[9g/mL), place it on a hot plate and heat until it is completely dissolved, evaporate to about 5mL. Remove it and add 100mL of water to dissolve the salts. Cool it. Dilute it to 500mL with water. Mix it well. This solution contains about 0.017g in 1mL. 3.8 Iron solution: Weigh 14.5g of tri-smelted iron (FeCl26H2O3:0), put it in a 500mL beaker, add 200mL of water and 10mL of hydrochloric acid (pl.19g/mL), transfer it to a 1000mL volumetric flask after dissolution, dilute it to the scale with water, and mix it well. This melt contains 3mg of iron in 1mL. 3.9 Calcium standard solution; weigh 0.2497g of anhydrous calcium carbonate standard reagent that has been dried in an oven at 105~110℃ to a constant amount, place in a 250ml beaker, add 30mL of water and 10mL of hydrochloric acid (1.19g/mL), heat to dissolve and boil for 2min, cool to room temperature, transfer to a 1200mL volumetric flask, dilute to the mark with water, and mix well. This solution contains 100g of calcium in 1ml. 4 Instruments
In addition to general instruments, the following instruments are also required
4.1 Platinum IIL, volume of about 150~200ml,
4.2 Atomic absorption spectrometer with air-acetylene burner, 4.3 Calcium hollow cathode lamp.
Approved by the Ministry of Metallurgical Industry of the People's Republic of China on September 8, 1988 and implemented on January 1, 1990
5 Sample
The sample should pass through a 0.125mm sieve
6 Analysis steps
6.1 Safety measures
GB 4333 8—88
When the gastric perchloric acid smoke is released, there should be no ammonia or organic matter nearby to prevent explosion. 6.2 Number of measurements
The same sample should be analyzed twice independently and the average value should be taken. 6.3 Test quantity
Weigh a maximum of 0.1000 g of sample.
6.4 Blank test
Carry out a blank test with the sample.
6.5 Instrument test
When the original absorption spectrometer has been calibrated to the maximum state, its precision should meet the following two indicators. 6.5.1 Measure the absorbance of the highest calibration solution 10 times and calculate the lower mean and standard deviation of the absorbance. The coefficient of variation of the standard deviation relative to the average absorbance shall not exceed 1.5%. 6.5.2 Measure the absorbance of the lowest calibration solution (not the zero calibration solution) 10 times and calculate its standard deviation. The coefficient of variation of the standard deviation relative to the average absorbance of the highest calibration solution shall not exceed 0.5%. See Appendix A (Supplement) for the calculation of the coefficient of variation. See Appendix B (Reference) for the working parameters of the WYX-401 atomic absorption spectrometer. 6.6 DeterminationwwW.bzxz.Net
6.6.1 Place the sample (6.3) in platinum blood (1.1), add 3mL nitric acid (3.1), add 1mL hydrofluoric acid (3.2), heat on a hot plate to dissolve, add 5mL perfluoric acid (3.3), continue heating and evaporating until dry. Remove and cool. 6.6.2 Add 10ml hydrochloric acid (3.4), heat to dissolve the salts, remove and cool. 6.6.3 Transfer the solution to a 200mL volumetric flask, add 11mL of ascorbic acid solution (3.6); if the test solution contains 50mg of iron, add 20mL of ascorbic acid solution, mix well, add 10.00mL of solution (3.7), dilute to the mark with water and mix well. If the calcium concentration in the test solution exceeds the highest calcium concentration in the working curve, transfer 50.00mL of solution from the volumetric flask, place in a 100mL volumetric flask, add 2.5mL of iron solution (3.7), dilute to the mark with hydrochloric acid (3.5), and mix well. 6.6.4 Measure the absorbance of the solution at a wavelength of 422.7nm on an atomic absorption spectrometer using an air-acetylene flame and zero with water. 6.7 Drawing of calibration curve
6.7.1 Drawing of low concentration calibration curve
6.7.1.1 Pipette 0, 1.50, 3.00, 4.50, 6.00, 7.50, 9.00 ml of calcium standard solution (3.9) and place them in a set of 200 ml volumetric flasks.
6.7.1.2 Add the same amount of calcium solution (3.8) as the amount of iron in the sample (6.3), add 10 ml of ascorbic acid solution (3.6), and mix. Add 10.0 ml of quenching solution (3.7), dilute to the mark with hydrochloric acid (3.5), and mix. Determine the absorbance of the calibration solution according to 6.6.1, subtract the absorbance of the compensation solution (calibration solution without calcium), and draw the calibration curve with the calcium concentration as the horizontal axis and the absorbance as the vertical axis. 6.7.2 Drawing of high concentration calibration curve
6.7.2.1 Take 0, 3.00, 6.00, 9.00, 12.00, 15.00, 18.00 mL of calcium standard solution (3.9) and place them in a group of 200 mL volumetric flasks respectively. Then proceed as in 6.7.1.2. B.7.2.2 Take out 50 mL of solution from each of the 200 mL volumetric flasks (6.7.2.1) and place them in a group of 100 mL volumetric flasks respectively. Add 2.5 mL of lanthanum solution (3.7), dilute to the mark with hydrochloric acid (3.5), and mix. Then determine the absorbance of the calibration solution as in 6.6.4 and subtract the absorbance of the compensation solution (calibration solution without calcium). Draw the calibration curve with the calcium concentration as the abscissa and the absorbance as the ordinate. 7 Calculation of analytical results
Calculate the percentage of calcium according to the following formula!
In the formula +
GB4333.8-88
(c) 2)V
Ca(%)
Calcium concentration of the test solution obtained from the calibration curve +ug/mL: -Calcium concentration of the blank test obtained from the calibration curve, 1g/mL, ---Total volume of the test solution mL,
m—Sample volume, g;
-→Test solution fraction ratio.
8 Allowable difference
The difference in analytical results between laboratories should not be greater than the allowable difference listed in the following table. Calcium
0. 050 ~~0. 100
≥0.100～0,250
>0.251~. 500
>0,500~0.800
≥0. 800-~1. 200
>1. 20~1. 80
GB 4333.8—88
Appendix A
Calculation of coefficient of variation of precision index
(Supplement)
The calculation formula of coefficient of variation of absorbance readings of the highest concentration calibration solution and the lowest concentration calibration solution is as follows: =
·Coefficient of variation of absorbance of the highest concentration calibration solution, coefficient of variation of absorbance of the lowest concentration calibration solution:Absorbance of the highest concentration calibration solution;
Average value of the highest concentration calibration solution absorbance: Absorbance of the lowest concentration calibration solution;
Average value of the lowest concentration calibration solution absorbance. Appendix B
WYX-401 Atomic Absorption Spectroscopy Working Parameters (Reference)
Working Condition Parameters
Additional Notes:
This standard was drafted by Gulin Ferroalloy Factory.
The main drafters of this standard are Duan Shudong and Dong Baozhen. Burner Height
This standard's horizontal grade mark GB4333.8-881 Burner Angle
Air Flow
Acetylene Flow
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