GB/T 4702.5-1984 Chemical analysis of chromium metal - Determination of aluminum content by atomic absorption spectrophotometry GB/T4702.5-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of chromium metalThe atomic absorption spectrophoto -metric method for the determinationof aluminium content
This standard is applicable to the determination of aluminium content in chromium metal, with a determination range of 0.10-1.00%. UDC 669.26 : 543
422 : 546.621
GB 4702.5-84www.bzxz.net
This standard complies with GB1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". Summary of the method
The sample is decomposed with perchloric acid to produce smoke, then diluted with water to a certain volume, and the absorbance of iron is measured with an atomic absorption spectrophotometer.
2 Reagents
2.1 Perchloric acid (specific gravity 1.67).
2.2 Electrolytic chromium.
2.3 Aluminum standard solution: weigh 0.5000g aluminum (99.9% or more), place in a 200ml beaker, add 50ml hydrochloric acid (1+1) and heat to dissolve, cool to room temperature, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 0.5mg aluminum in 1ml. 3 Apparatus
Original absorption spectrophotometer, with aluminum hollow cathode lamp, nitrous oxide-acetylene burner. The working conditions of the instrument are shown in Appendix A (reference).
4 Sample
The sample should pass through a 1.68mm sieve.
5 Analysis steps
5.1 Determination quantity
The same sample solution should be measured twice separately and the average value should be taken. 5.2 Sample quantity
Weigh 1.000g of sample.
5.3 Empty test
Carry out an empty test with the sample.
5.4 Determination
5.4.1 Place the sample (5.2) in a 500ml beaker, cover with Table IIIl, add 15ml perchloric acid (2.1) and heat to dissolve it, continue heating until smoke is generated for about 10 minutes, and cool to room temperature. 5.4.2 Add 50ml warm water to dissolve the salts, filter into a 100ml volumetric flask with quantitative filter paper, and wash the filter paper with warm water, cool to room temperature, dilute with water to the scale, and mix well.
GB 4702. 5—84
5.4.3 Adjust the atomic absorption spectrophotometer to the best working state. Take the test solution (5.4.2) and measure its absorbance at the analytical line of 309.2nm (or 396.2nm) in the nitrous oxide-acetylene flame on the atomic absorption spectrophotometer. Use water to adjust the zero point and subtract the absorbance of the blank sample from the measured absorbance. Find the corresponding aluminum content from the working curve. 5.5 Drawing of working curve
5.5.1 Take 0, 1.00, 2.00, 3.00, 4.00, 5.00, 6.00 ml of aluminum standard solution (2.3) and place them in a group of 500 ml beakers respectively. Add 1.000 g of electrolytic metal chromium (2.2) and 15 ml of perchloric acid (2.1) and heat to dissolve it. Continue heating until smoke is generated for about 10 minutes. Cool to room temperature and measure its absorbance according to 5.4.2 and 5.4.3. 5.5.2 Draw the working curve with the aluminum content as the horizontal axis and the absorbance (minus the absorbance of the reagent blank) as the vertical axis. 6 Calculation of analysis results
Calculate the percentage of aluminum according to the following formula:
Where: m is the aluminum content obtained from the working curve, mg, mo
-sample amount, g.
The analysis results are expressed to two decimal places. The allowable difference
mg×1000
The difference in the analysis results between laboratories should not be greater than the allowable difference listed in the following table. %
0.10~0.20
0.20~0.50
>0.50~1.00
GB4702.5—84
Appendix A
Instrument working conditions
(reference)
The reference working conditions for determining the amount of aluminum using a 18080 atomic absorption spectrophotometer are as follows: Analysis line
(nm）
Additional instructions:
Lamp current
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Hunan Ferroalloy Factory. Flame height
Pressure (kgf/cm2)
Oxidation "Nitrogen
(0.157MPa)
(0.029MPa)
Flow rate (1/min)
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB582-65 "Methods for Chemical Analysis of Chromium" shall be invalid. 210
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