GB/T 4324.16-1984 Chemical analysis of tungsten - Determination of magnesium content by atomic absorption spectrophotometry GB/T4324.16-1984 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of tungsten
Atomic absorption spectrophotometric methodfor the determination of magnesium contentUDC 669.27:543
.42 :546.46
GB 4324.16—84
This standard is applicable to the determination of magnesium content in tungsten powder, tungsten bar, tungsten dioxide, tungstic acid and ammonium paratungstate. Determination range: 0.000300.020%. This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
After the sample is decomposed by chlorine oxide, in the presence of ammonium hydroxide, add an appropriate amount of citric acid to prevent the solution from becoming turbid. The standard addition method is used at an atomic absorption spectrophotometer wavelength of 285.2nm and an air acetylene flame to determine magnesium. 2 Reagents
Ammonium chloride oxide (specific gravity 0.90), ultrapure. 2.2 Oxygen peroxide (specific gravity 1.10), ultrapure. 2.3 Citric acid solution (50%).
2.4 Magnesium standard solution
2.4.1 Weigh 0.1000g of metallic magnesium (99.99%), place it in a 200ml beaker, add 50ml of water and 5ml of nitric acid (specific gravity 1.42), heat to dissolve, cool, transfer to a 1000ml volumetric flask, dilute to the mark with water, and mix. This solution contains 100μg of magnesium in 1ml. 2.4.2 Take 1U.00ml magnesium standard solution (2.4.1), put it into a 100ml volumetric flask, dilute it to the mark with water, and mix it. This solution contains 10μg magnesium in 1ml.
3 Instruments
Original absorption spectrophotometer, magnesium hollow cathode lamp. The absorption spectrophotometer used should meet the following indicators. Minimum stability: The absorbance of the highest concentration standard solution of the arithmetic difference concentration standard solution used in the curve should not be lower than - + 0.250. Linearity of the curve: The difference between the absorbance of the highest and second highest concentration standard solutions used in the curve should not be less than 0.8 times the difference between the absorbance of the lowest concentration standard solution and the zero concentration solution. Minimum stability: The coefficient of variation of the absorbance of the highest concentration standard solution and the zero concentration solution measured multiple times relative to the mean absorbance of the highest concentration standard solution should be less than 1.5% and 0.6% respectively. For the calculation of the minimum stability coefficient of variation, see Appendix A (supplementary), and for the WFX·110 atomic absorption spectrophotometer, see Appendix B (reference). 4 Samples
The tungsten bar should be crushed and passed through a 120 sieve.
Promulgated by the National Bureau of Standards on April 12, 1984
Implemented on March 1, 1985
5 Analysis steps
5.1 Determination quantity
GB 4824.16—84
Three samples should be weighed for determination during analysis. The measured values ​​should be within the allowable indoor difference and the average value should be taken. 5.2 Sample force bzxz.net
Weigh 0.1000~2.000g of sample.
5.3 Blank test
Carry out a blank test with the sample.
5.4 Determination
5.4.1 Place the sample (5.2) in a 200ml quartz beaker, moisten with water, add 10-20ml hydrogen peroxide (22) in portions, cover with a plastic beaker, dissolve under slight heat, remove, and cool. 5.4.2 Add 2-4ml ammonium hydroxide (2.1), heat and boil for 1-2 minutes, cool, and add 2-4ml citric acid solution (2.3) 5.4.3 Transfer the solution to a 50ml volumetric flask, dilute to the mark with water, and mix well. 5.4.4 Place the solution on the original absorption spectrophotometer at a wavelength of 283.2nm, use an air-acetylene lean flame, adjust to zero with water, and measure the absorbance of magnesium.
Find out the corresponding magnesium concentration from the working curve. Drawing of the working curve
Carry out the same sample volume according to 5.4.1 and 5.4.2. Transfer them to a group of 50ml volumetric bottles, and then add 0.00, 100
2.003.00, 4.00ml of magnesium standard solution (2.4.2) respectively, dilute to the scale with water, and mix well. The following is carried out according to 5.4.4. Use magnesium concentration as the horizontal axis and absorbance (minus the absorbance of zero concentration solution) as the vertical axis to draw the working curve.
Calculation of analysis results
Calculate the percentage of magnesium according to the following formula:
Mg (%) =
(m2-m,)
Wherein: m2-
the magnesium concentration obtained from the plot, g/mm-the magnesium concentration of the blank sample obtained from the working curve, ug/ml: y—total volume of test solution, ml;
sample volume, g.
Allowable difference
The difference in analytical results between laboratories should not be greater than the allowable difference listed in the following table. %
0. 00030 ~ 0. 00090
>0,0009 ~ 0. 0030
>0.0030 -0.0060
~*0,0060 -0.009
~0.009 - 0.020
Allowable difference
GB4324.16-84
Appendix A
Calculation of minimum stability coefficient of variation
(Supplement)
The coefficient of variation of the absorbance reading of the highest concentration standard solution and the zero concentration solution is calculated as follows: A.1
GB 4324.17—B4
Appendix B
Working condition parameters of WFX-110 atomic absorption spectrophotometer (reference)
Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide! This standard was drafted by Zhuzhou Cemented Carbide Factory. The main drafter of this standard is Tang Xiwu.
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