GB/T 4325.18-1984 Chemical analysis of molybdenum - Atomic absorption spectrophotometric method for determination of potassium content GB/T4325.18-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of molybdenumThe atomic absorption spectrophotometric methodfor the determination of potassium contentUDC 669.28 : 543
.42 : 546. 32
GB 4325.18—84
This standard is applicable to the determination of potassium content in molybdenum powder, molybdenum bar, molybdenum trioxide and ammonium molybdate. Determination range: 0.0010~0.150%. This standard complies with GB1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
The sample is decomposed with hydrogen peroxide (ammonium molybdate is dissolved in water with a small amount of hydrogen peroxide), chlorination is used as a deionizer, and its absorbance is measured under selected conditions.
2 Reagents
2.1 Hydrogen peroxide (specific gravity 1,10).
2.2 Chloride solution (25mg/ml).
2.3 Double distilled water (this water is used in this method). 2.4 Molybdenum matrix: It should have basically the same properties as the sample and contain no potassium or a very small amount of potassium. 2.5 Potassium standard solution
2.5.1 Weigh 0.1907g of potassium chloride (more than 99.9%) that has been pre-calcined at 550℃, place it in a quartz beaker, dissolve it with water, transfer it to a 1000ml volumetric flask, dilute it to the mark with water, and mix it. This solution contains 100μg potassium in 1ml. 2.5.2 Transfer 10.00ml of potassium standard solution (2.5.1), place it in a 100ml volumetric flask, dilute it to the mark with water, and mix it. This solution contains 10μg potassium in 1ml.
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 equal concentration standard solution used in the working curve should not be less than 0.25. Working curve linearity: The difference between the absorbance of the highest and second highest concentration standard solutions in the equal concentration standard solution should not be less than 0.9 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 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 atomic absorption spectrophotometer are shown in Appendix B (Reference). 3.2 Quartz beaker (with lid), 150~200ml. 4 SamplewwW.bzxz.Net
The molybdenum bar should be crushed and passed through a 80-mesh screen.
Promulgated by the National Bureau of Standards on April 12, 1984
Implemented on March 1, 1985
5 Analysis steps
5.1 Determination quantity
GB 4325.18--84
Three samples should be weighed for determination during analysis. The measured values ​​should be within the indoor tolerance and the average value should be taken. 5.2 Sample quantity
Weigh the sample quantity according to Table 1.
Potassium, %
0.002 ~0.01
>0.01~0.10
>0.10~0.15
5.3 Blank test
Carry out a blank test along with the sample.
5.4 Determination
5.4.1 Molybdenum powder, molybdenum strip and trioxide
Sample plate, B
5.4.1.1 Place the sample (5.2) in a quartz beaker, moisten it with a small amount of water, and drop (or add in batches) 6-8 ml of hydrogen peroxide (2.1). After the violent reaction stops, move it to a hot plate and heat it at low temperature until the sample is completely dissolved. Remove it, rinse the table and the wall of the cup with water, add 50 ml of water, and heat it to boil for about 1 minute to drive off excess hydrogen peroxide. 5.4.1.2 Remove it and cool it slightly, add 1 ml of chlorination solution (2.2), transfer it to a 100 ml volumetric flask, dilute it to the scale with water, and mix it well. 5.4.1.3 Measure the absorbance of potassium on an atomic absorption spectrophotometer at a wavelength of 766.5 nm, using an air-acetylene flame and adjusting it to zero with water.
5.4.1.4 Find the corresponding potassium concentration from the working curve (or calculate the result by comparison method). 5.4.2 Ammonium molybdate
Place the sample in a quartz beaker, add about 50ml of water to dissolve it, add 1ml of hydrogen peroxide (2.1), heat and boil for about 1min. The following shall be carried out according to Items 5.4.1.2 to 5.4.1.4. 5.5 Drawing of working curve
Weigh six portions of molybdenum matrix (2.4) according to the sample amount in Table 1, place them in quartz beakers respectively, and add potassium standard solution (2.5.1 or 2.5.2) according to Table 2. The following shall be carried out according to Items 5.4.1.1 to 5.4.1.3 or Items 5.4.2 and 5.4.1.2 to 5.4.1.3 in Item 5.4.1 according to the type of sample. With potassium concentration as the abscissa and absorbance (minus the absorbance of the compensation solution) as the ordinate, draw a working curve. Table 2
Potassium, %
Potassium standard solution
Amount of potassium standard solution added
0.002~0.01
>0.01~0.15
Calculation of analysis results
Calculate the percentage of potassium according to the following formula:
Where: m1-
7Allowance difference
GB4325.18—84
(m,- m2)×V
m×106
-The potassium concentration of the sample solution obtained from the working curve, μg/ml, -The potassium concentration of the blank made with the sample obtained from the working curve, μg/ml,Total volume of test solution, ml
Sample volume, g.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 3. Table 3
0.0010 ~0.0025
>0. 0025 ~0.0050
>0.0050 ~0.0150
>0.015~0.025
Allowable difference
>0.025~0.060
>0.060~0.090
>0.090~0.120
>0.120~0.150
Allowable difference
GB 4325.18—84
Appendix A
Calculation of the minimum stability coefficient of variation
(Supplement)
The formula for calculating the coefficient of variation of the absorbance readings of the highest concentration standard solution and the zero concentration solution is as follows: Al
Wu Zhong:
2(CC)2
2(0-0)2
percent coefficient of variation of the absorbance of the highest concentration standard solution; percent coefficient of variation of the absorbance of the zero concentration solution, average value of the absorbance of the highest concentration standard solution, absorbance of the highest concentration standard solution
average value of the absorbance of the zero concentration solution;
Absorbance of zero concentration solution:
number of measurements.
·（A1）
GB4325.18-—84
Appendix B
Working Condition Parameters of WFX-110 Atomic Absorption Spectrophotometer (reference)
Working Condition Parameters
Note: The content range is less than 0.01%, and the scale is expanded to 2 times. Additional Notes:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is drafted by Zhuzhou Cemented Carbide Factory. This standard is drafted by Zhuzhou Cemented Carbide Factory. The main drafter of this standard is Chen Fushi.
Lamp current
Burner height
Air flow plate
Acetylene flow
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