GB/T 4324.18-1984 Chemical analysis of tungsten - Determination of potassium content by atomic absorption spectrophotometry GB/T4324.18-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of tungsten
Atomic absorption spectrophotometry for the determination of potassium content
Methods for chemical analysis of tungstenThe atomic absorption spectrophotometrie methodfor the determination of potassiun contentUDC 669.27: 543
.42 646.32
GB ±324.18—84
This standard is applicable to the determination of potassium content in tungsten powder, tungsten bar, pigeon trioxide, tungstic acid and ammonium paratungstate. Determination range: 0.00050~0.080%. This standard complies with GB1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
Tungsten powder and tungsten bars are decomposed with hydrogen peroxide, blue cyanide tungsten and tungstic acid are dissolved with ammonium xenon, ammonium paratungstate is dissolved with water and a small amount of ammonium hydroxide, tungsten is complexed with citric acid, chlorination is used as a deionizer, and its absorbance is measured under selected conditions. 2 Reagents
Ammonium hydroxide (specific gravity 0.90), extra pure. 2.1
2.2 Peroxide (specific gravity 1.10), ultra pure. 2.8 Citric acid solution (50%).
2.4 Chlorination solution (20mg/ml).
Bidistilled water (this water is used in this method). 2. 5
2.6 Tungsten matrix: It should have basically the same properties as the sample and contain no potassium or very little potassium. 2.7 Potassium standard solutionbzxZ.net
2.7.1 Weigh 0.1907g of potassium chloride (99.9% or more) pre-burned at 550℃, place in a quartz beaker, dissolve in water, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 100μg potassium per ml. 2.7.2 Transfer 10.00ml of potassium standard solution (2.7.1), place in a 100ml volumetric flask, dilute to scale with water, and mix. This solution contains 10ug potassium per ml.
3 Instruments
3.1 Atomic absorption spectrophotometer equipped with air-acetylene burner and potassium hollow cathode lamp. The atomic absorption spectrophotometer used should meet the following indicators. Minimum sensitivity: The absorbance of the highest concentration standard solution of the arithmetic difference concentration standard solution used in the working curve should not be less than 0.25. The curve is linear, and the difference between the absorbance of the highest and second highest concentration standard solutions of equal concentrations should not be less than 0.9 times the difference between the absorbance of the lowest concentration and the zero concentration. Minimum stability: The coefficient of variation of the absorbance obtained by multiple measurements of the highest concentration standard solution and the zero concentration solution used in the working curve relative to the average absorbance of the highest concentration standard solution should be less than 1.5% and 0.6%, respectively. The calculation of the minimum stability coefficient of variation is shown in Appendix A (Supplement).
The working condition parameters of the WFX-110 original absorption spectrophotometer are shown in Appendix B (Reference). 3.2 Quartz beaker (with lid), 150~200ml. Issued by the National Bureau of Standards on April 12, 1984
Implemented on March 1, 1985
The tungsten bar should be crushed and passed through a 120 concave sieve.
5 Analysis steps
5.1 Determination quantity
GB4324.18-84
Three samples should be weighed for determination during analysis. The measured value should be within the allowable error, and the average value should be taken
5.2 Sample quantity
Weigh the sample quantity according to the table.
Potassium, %
Sample, 5
5.3 Blank test
Carry out a blank test with the sample.
5. 4 Determination
5.4.1 Tungsten powder, tungsten bar,
20.001~0.03
0.5000~1.000
20.03~0.08
5.4.1.1 Place the sample (5.2) in a quartz beaker, moisten with water, add dropwise (or in portions) 5~12㎡l of hydrogen peroxide (2.2), heat slightly to dissolve the sample completely [If there is white turbidity, add 1~2ml of ammonium hydroxide (2.1) to make the solution clear , add 2ml citric acid solution (2.3), add 20ml water and boil. After cooling, add 1ml chlorinated sodium solution (2.4), transfer to a 100ml volumetric flask, dilute to the mark with water, and mix. 5.4.1.2
Put the solution in an absorption spectrophotometer at a wavelength of 766.5nm, use air-acetylene flame, adjust to zero with water, and measure the absorbance of potassium.
Calculate the corresponding potassium concentration from the working curve (or calculate the result by comparison method). 5.4.1. 4
5.4.2 Tungsten trioxide, tungsten acid
Put the sample (5.2) in a quartz beaker, add 30~40ml ammonium hydroxide (2.1), heat until the sample is completely dissolved, evaporate to a volume of 10~15ml, remove, and add 2ml citric acid solution (2.3). The following is carried out according to 5.4.1.2~5.4.1.4. 5.4,3 Ammonium paratungstate
Put the sample (5.2) in a quartz beaker, add about 60ml water, then add 1~2ml ammonium chloride (2.1), boil until the sample is completely dissolved: add 2ml citric acid solution (2.3). The following is carried out according to 5.4.1.2~5.4.1.4. .5.5 Drawing of the curve
Weigh the tungsten base according to Table [1 Sample amount Six portions of the sample (2.6) are placed in quartz beakers respectively. Potassium standard solution (2.7.1 or 2.7.2) is added according to Table 2. The following is carried out according to 5.4.1.1~5.4.1.3 or 5.4.2 or 5.4.3 and 5.4.1.2~5.4.1.3 according to the type of sample. Draw a working curve with potassium concentration as the horizontal axis and absorbance (minus the absorbance of the compensation solution) as the vertical axis. Table 2
Potassium, %
Potassium standard solution
Amount of potassium standard solution added, ml
>0.008~0.08
<0.0005~0.008
Calculation of analysis results
Calculate the percentage of potassium according to the following formula:
GB 4324.1884
(m-m2)V
K (%)=
m×106
-Potassium concentration of the sample solution obtained from the working curve, g/ml, m2-Potassium concentration of the blank prepared with the sample obtained from the working curve, μg/mlV-Total volume of the test solution, ml
m-Sample volume, g.
7 Allowable difference
The difference in analytical results between laboratories should not exceed the allowable difference listed in Table 3. 3
0.0005~0.0015
>0.0015~0.0025
≥0.0025~0.0040
>0.0040~0.0080
>0.008~0.015
>0.015~0.050
0.050-0.086
Allowable difference
GB 4324.18—84
Appendix A
Calculation of minimum stability coefficient of variation
(Supplement)
The formula for calculating the coefficient of variation of the photometric readings of the highest concentration standard solution and the zero concentration solution is as follows: A.1
2 (0 -0)2
The first percentage coefficient of variation of the absorbance of the most concentrated standard solution; S
The percentage coefficient of variation of the absorbance of the zero concentration solution: -The value of the absorbance of the highest concentration standard solution:
The average value of the absorbance of the zero concentration solution in the absorbance of the highest concentration standard solution;
The absorbance of the zero concentration solution:
The number of measurements.
Additional instructions:
GB 432418—84
Appendix
Working condition parameters of WFX-110 atomic absorption spectrophotometer (reference part)
tCurrent
This standard is proposed by: Ministry of Metallurgy of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide. This standard was drafted by Zhuzhou Cemented Carbide! This standard was drafted by Zhuzhou Cemented Carbide! The main drafter of this standard is Tang Xiwu.
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