GB/T 4324.6-1984 Chemical analysis of tungsten - o-phenanthroline photometric method for determination of iron content
Some standard content:
National Standard of the People's Republic of China
Chemical analysis method of tungsten
Methods for chemical analysis of tungstenThe ortha - pheanthroline photometric method forthe determiation of iron contentUDC 669.t7: 54$
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GE4324.6 —84
This standard is applicable to the determination of iron content in tungsten powder, pigeon strips, tungsten trioxide, tungstic acid, and ammonium paratungstate. Determination range: 0.0005~0.10%. This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is decomposed by ammonium sulfate and tungsten is complexed with citric acid. At pH 7, iron is reduced with hydroxylamine hydrochloride. Iron (II) and o-nitrophenanthroline form an orange-red complex, and its absorbance is measured. 2 Reagents
2.1 Potassium iodide.
2.2 Triazine.
2.3 Sulfuric acid (specific gravity 1.84), high-grade purity. 2.4 Ammonium hydroxide (specific gravity .90).
2.5 Sodium perfluoride solution, transfer 200ml perfluoride (1+1), adjust to pH 7 with 40% sodium hydroxide solution (check with pH test paper).
2.6 Ammonium sulfate solution (50%). The purification steps are as follows: weigh 250g of ammonium sulfate and dissolve it in 400ml of water, adjust the pH to 7 with ammonium hydroxide (2.4) (check with test paper), add 2.5nml of sodium perchlorate solution (2.5), 2ml of hydroxylamine hydrochloride solution (2.8), 3ml of o-nitropropene (2,7), add boiling water, add 3 ml of potassium ion, wait for the solution to dissolve, filter it in a separatory funnel with rapid quantitative filter paper, and dilute it with 393ml of water, add 120-30ml of chlorinated paraffin (2.2), shake it for 2min, let it stand for stratification, discard the organic phase, and repeatedly purify the aqueous phase by hand (2.2) until the organic phase is colored, and put the aqueous phase into a reagent bottle for use. z.1 o-Diphenylamine solution (0.3%): weigh 0.3g of o-nitropropene and place it in a 300ml beaker, add 10ml of ethanol, dissolve it, dilute it with water to 100m], and mix it.
2. Hydroxylamine hydrochloride solution (20%). Purification step: weigh 50g hydroxylamine hydrochloride and place it in a 500ml beaker, add 150ml water to dissolve, adjust to pH 7 with ammonium hydroxide (2.4) (check with pH test paper), add 20ml o-difluorophenanthrene solution (2.7), heat to boiling, remove the flask, add 3g potassium hydroxide (2.1?, after dissolving, transfer to a separatory funnel with water and dilute to 250g), extract with chloroform (2.2) several times (20ml each time, stirring for 2min), until the organic phase turns pale. Discard the organic phase, put the aqueous phase into a reagent bottle for later use. 2.9 Citric acid solution (50%). The purification steps are as follows: weigh 250g of citric acid, place it in a 1000ml beaker, add 200ml of water to dissolve it, adjust the pH to 7 with ammonium hydroxide (2.4) (check with pH test paper), add 2.5ml of sodium perchlorate solution (2.5), 2g of hydroxylamine hydrochloride, and 20ml of o-phenanthroline solution (2.7) in sequence, batch boil, add 3g of potassium iodide (2.1), dissolve it, filter it with rapid quantitative filter paper, and dilute it with water to 500ml, extract it with tri-micromethane (2.2) several times (20ml each time, oscillate for 2min), until the organic phase is colorless, discard the organic phase, and put the aqueous phase into a reagent bottle for standby use. 2.10 Disodium ethylenediaminetetraacetate (EDTA) solution (10%): Weigh 10g EDTA (super pure) in a 250ml beaker, add 90ml water, heat (50-80℃) to dissolve, adjust pH to 7 with ammonium hydroxide (2.4) (check with pH test paper), dilute to 100ml with water, mix, and set aside.
z.11 Iron standard solution
GB 4324.6-84
2.11.1 Weigh 0.1000g pure iron (99.99%), place in a 300ml beaker, add 20ml sulfuric acid (1+1), heat to dissolve, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. 1 ml of this solution contains 0.10 mg of iron. 2.11.2 Take 10.00 ml of the standard iron solution (2.11.1), place it in a 100 ml volumetric flask, dilute to the mark with water, and mix well. 1 ml of this solution contains 10 μg of iron.
The tungsten bar should be crushed and passed through a 120 mesh sieve.
Fractional analysis steps
4.1 Determination quantity
Three samples should be weighed for determination during analysis. The measured values should be within the indoor allowable difference and the average value should be taken. 4. 2 Sample quantitybzxZ.net
Weigh 0.1000~0.5000 g of sample.
4.3 Blank test
Carry out a blank test along with the sample.
4.4 Determination
4.4.1 Place the sample (4.2) in a 150ml conical flask, add 8ml ammonium sulfate solution (2.6) and 4ml sulfuric acid (2.3), heat to dissolve, remove and cool.
4.4.2 Add 8ml citric acid solution (2.9), mix, add 10ml ammonium hydroxide (2.4), 10ml water, boil for 1-2min, remove and cool.
4.4.8 Add 2ml EDTA solution (2.10), adjust to pH 7 with ammonium hydroxide (2.4) (check with pH test paper), add 3ml hydroxylamine hydrochloride solution (2.8), 2ml o-diazepine solution (2.7), mix, keep warm in a water bath at 60-70℃ for 15min, remove, cool to room temperature, transfer to a 50ml container with water and dilute to the scale, mix. 4.4.4 Transfer part of the solution into a 2cm colorimetric bottle, use water as a reference, and measure its absorbance at 510mm from the side of the spectrophotometer. 4.4.5 Subtract the absorbance of the blank made with the sample. Find the corresponding iron content from the working curve. 4.5 Drawing of the working curve
Transfer 0.00, 1.00, 2.00, 3.00, 4.00, 5.00, 6.00ml of iron standard solution (2.11.2) and place them in ten groups of 50ml volumetric flasks respectively. Add 2ml of citric acid solution (2.9) and keep the volume of the solution at about 30ml. The following is carried out according to 4.4.3~4.4.4, measure its absorbance, and subtract the absorbance of the reagent blank. Draw the working curve with the amount of iron as the horizontal axis and the absorbance as the vertical axis. Calculation of analysis results
Calculate the percentage of iron according to the following formula:
Wherein: mi
6Permissible difference
The amount of iron found from the above curve, g;
-sample amount, g.
m×10n
The difference in analysis results between laboratories should not be greater than the permissible difference listed in the following table. 19
Additional Notes:
0.0005~0.0020
>0.0020~0.0040
>0.0040~0.0080
>0. 0080 ~0.0200
>0.020~0.040
=0.040~0.1
GB4324.6—84
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 Co., Ltd. This standard is drafted by Benxi Zinc-Molybdenum Products Co., Ltd. The main drafters of this standard are Li Xiuyun and Xing Xiaolang. Allowable difference
Since the implementation of this standard, the former Ministry of Metallurgical Industry Standard YB895-77 "Tungsten Chemical Analysis Method" will be invalid 20.
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