GB/T 4324.15-1984 Chemical analysis of tungsten - Chlorophosphonazo I spectrophotometric method for determination of magnesium content
Some standard content:
National Standard of the People's Republic of China
Chemical analysis method of tungsten
Methods for chemicat analysis of tungsten The chlorophosphonazo I photomietric method for the determination of magneslum content UDC 669.27 :543
.42:546.46
CB 4324.15—B4
This standard is applicable to the determination of magnesium content in tungsten powder, tungsten rod, tungsten monoxide, tungstic acid and ammonium paratungstate. Determination range: 0.00030～0.020%. 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 by hydrogen peroxide (sample tungsten powder, tungsten bar) or sodium hydroxide (sample tungsten dioxide, tungsten acid, ammonium paratungstate), and magnesium hydroxide is adsorbed by activated carbon in about 0.5M sodium hydroxide solution. A small amount of residual impurity elements are masked by monoethanolamine, o-phenanthroline, and EGTA-lead solution. At about pH 10.4, chlorophosphine is used as a color developer to determine the amount of magnesium by photometry. 2 Reagents
2.1 Activated carbon: About 10g of activated carbon is placed in a 300ml beaker, and 100ml of hydrochloric acid (2.3) is added. Heat for 2h, pour out part of the hydrochloric acid by decantation, and then add 100ml of hydrochloric acid (2.3) and soak for 24h. Filter, wash with water 10 times, and dry at 110°C. 2.2 Hydrochloric acid (specific gravity 1.19), high-grade purity. 2.3 Hydrochloric acid (11), high-grade purity.
Mix.
Hydrochloric acid (1+15), high-grade purity.
Sodium hydroxide solution (20%), high-grade purity. Sodium hydrogen sulfide solution (2%), high-grade purity. Hydrogen peroxide (specific gravity 1.10), high-grade purity. Triethanolamine solution (11).
o-Diazepine solution: 2g o-Diazepine is dissolved in 300ml 95% ethanol, and 199ml water, 1ml tetraethylenepentamine, ethanol-bis(2-amino-2-yl ether)-tetraacetic acid (EGTA)-lead solution: weigh Take 1.900g EGTA, put it in a 2.10
30ml beaker, add 200ml water, dissolve it with sodium hydroxide solution (2.5), and adjust it to neutral, then add 5 drops in excess. Weigh 1.800g lead nitrate [Pb(N(：)2*2H,O) and dissolve it in 300ml water, combine the above two solutions and mix. 2.11 Borax-sodium hydroxide buffer solution (pl110.7): Weigh 50g high-grade pure borax and dissolve it in F\950ml water, adjust it to pH10.7 with sodium hydroxide solution (2,5) (about 5U.2ml is needed), and filter. 2.12 Azo chlorophosphonium I solution (0.03%). 2.13 Ethylene monoamineμ Disodium acetate (FDTA) solution (5%): Weigh 5 EDTA and dissolve it in a small amount of water, neutralize it with sodium hydroxide solution (2.5), add 100 ml of water, and mix. 2.14 Iron solution: Weigh 0.2500 g of metallic iron (99.95% or more), place it in a 1200 ml beaker, add a small amount of water and 5 ml of hydrochloric acid (2.3), wait for it to dissolve, add 2 ml of nitric acid (1+1), heat for 10 minutes, cool, transfer to a 500 ml volumetric flask, dilute to full scale with water, and mix. This solution contains 0.5 mg of iron per ml. 2.15 Magnesium standard solution
Published by the National Bureau of Standards in 198401-12
1985 03-01 Implementation
GB 4324.15-B4
2.15.1 Weigh 0.1658g magnesium oxide (99.99% or more) pre-burned at 500℃ for 30min, place in a 200ml beaker, add 5ml hydrochloric acid (2.3), dissolve under slight heat, transfer to a 1000ml container, dilute to scale with water, and mix. This solution contains 100μg magnesium per ml.
2.15.2 Transfer 25.00ml magnesium standard solution (2.15.1), place in a 500ml container, dilute to scale with water, and mix. This solution contains 5μg magnesium per ml.
3 Instruments
Acidometer.
Electric magnetic stirrer (360r/min), the sample
calcium strip should be powdered and pass the 12011 net.
5 Analysis steps
5.1 Determination quantity
Three samples should be weighed for determination. The measured values should be within the allowable difference in the room and the average value should be taken. 5.2 Sample quantity
Weigh the sample according to Table 1.
Mg, Lu
Sample sensitization, g
5.3 Blank test
Carry out blank test with random samples.
5. 4 Determination
0.001-0.010
0,5000~0.1000
5.4.1 Tungsten powder, pigeon
5.4.1.1 Place the sample (5.2) in a 100ml polytetrafluoroethylene beaker (or quartz beaker), moisten it with water, add hydrogen peroxide (2.7) several times (1ml each time, about 10ml for 1g sample, about 3ml for 0.1g sample), decompose it, heat it on a low leakage current to completely decompose the sample, remove it, rinse the surface III l and the wall of the beaker with water, boil it for 10 minutes, and remove it. 5.4..2 Add 4ml hydrochloric acid (2.2), heat it for 10 minutes, remove it, and add! ml iron solution (2.11), stir, add sodium hydroxide solution (2.5) to 6% (check pH with paper), add 5% activated carbon (2.1), stir, add 8ml sodium hydroxide solution (2.5), the total volume is about 50ml, heat to low temperature, keep warm for 10min, remove, cool slightly, stir with electric magnetic stirrer for 10min, remove
5.4.1.3 Filter with slow quantitative filter paper, wash 1015 times with sodium hydroxide solution (2.6), and gently shake off the sodium hydroxide solution in the neck of the funnel.
5.4.1.4 Dissolve the precipitate in 100ml beaker with 15ml hydrochloric acid (2.3) at 70~80℃, evaporate on a low temperature electric furnace until soft, remove, add a little water, and heat slightly to dissolve the salt. Transfer the solution to a 50ml volumetric flask. 5.4.1.5 Add 5 ml of 1% ethanolamine solution (2.8), 5 ml of o-aza-non-free solution (2.9), 1 ml of FGTA-lead solution (2.10), and 5 ml of borax-sodium hydride buffer solution (2.11). Mix well after adding each reagent, and let stand for 2 to 5 minutes. Add 5 ml of azophosphine oxide I solution (2.12), dilute to the mark with water, mix well, and let stand for 15 minutes. 5.4.1.6 Transfer part of the solution to 3 gm colorimetric solution. Add 2 drops of EDTA solution (2.13) to the remaining drop, mix well, and use it as a reference. Measure the H absorbance at a wavelength of 572 nm on a spectrophotometer. 48
GB 4324.15--84
5.4.1.7 Subtract the absorbance of the blank prepared with the sample and find the corresponding amount of magnesium from the working curve. 5.4.2 Tungsten trioxide, tungstic acid, ammonium tungstate
Put the sample (5.2) in a 100ml polytetrafluoroethylene beaker (or quartz beaker), moisten it with water, add 3-5ml sodium hydroxide solution (2.5), heat it to dissolve the sample completely, remove it, and rinse the surface blood and the beaker wall with water. The following is carried out according to 5.4.1.2 to 5.4.1.7. 5.5 Drawing of working curve
Pipette 0.00, 0.50, 1.0g, 1.50, 2.00, 2.50, 3.00ml magnesium standard solution (2.15.2), respectively, and place them in a group of 50ml volumetric flasks, add 1ml hydrochloric acid (2.4), and then proceed to 5.4.1.5 to 5.4.1.6, measure its absorbance, subtract the absorbance of the reagent blank, and draw a working curve with the magnesium content as the horizontal axis and the absorbance as the vertical axis. Calculation of analysis results
Calculate the percentage of magnesium according to the following formula
Where: m—
Allowable difference
The amount of magnesium found from the working curve, qin! One sample amount, name.
The difference in analysis results between laboratories should not be less than the allowable difference listed in Table 2. Table 2
0.C0030~0.00090
0.0009 -0.0030bzxZ.net
2>0,003-0.006
0.006~0.009
0.009-0.020
Additional Notes:
This standard was proposed by the Ministry of Metallurgy of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide Research Institute. This standard was drafted by Hunan Metallurgical Research Institute. The main drafter of this standard has not yet been announced.
White From the month this standard is implemented, the former Ministry of Metallurgical Industry Standard YB895-77 "Calcium Chemical Analysis Method" will be invalid. 藕蝎稚17bzw.cn脆臂他饮藕颜红痕旅科5翅湖
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