GB/T 4702.12-1987 Chemical analysis method for chromium metal Oscillographic polarographic method for determination of bismuth content GB/T4702.12-1987 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of chromium metal
The oscitloplarographic method for thedetermination of bismuth content
This standard is applicable to the determination of bismuth content in chromium metal, with a determination range of 0.0003~0.0015%. UDC: 669.26
:543.253.06
GB4702.12.--87
This standard complies with GB1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
The sample is dissolved in hydrochloric acid, and ammonium citrate and EDTA are used to mask chromium and iron ions. In an ammonia medium, extract with copper reagent and chloroform, then back-extract with hydrochloric acid (113), and use PAR--garlic alcohol-sodium hydroxide mixed alkaline solution as the base solution. On the oscillographic polarograph, the peak potential measured is the peak height at 0.65V, and the analysis results are calculated by the standard comparison method. 2 Reagents
The water used for analysis is double distilled water. wwW.bzxz.Net
2.1 Nitric acid (1+1).
2.2 Hydrochloric acid (1-1), high-grade purity.
2.3 Hydrochloric acid (112), high-grade purity.
2.4 Ammonium citrate solution (50%),
2.5 EDTA (CHN20, Na22H.O) solution (10%). 2.6 Ammonium hydroxide (g6.90g/ml)
2.7 Copper reagent (sodium monoethyldithiocarbamate) solution (0.2%) 2.8 Triazine (01.48g/mb
2.9 Ammonia washing solution: weigh 150g ammonium citrate, 15g EDTA, U.4g copper reagent and 25ml ammonium hydroxide and dissolve in 10ml water.
2.10 Base solution: weigh 80g sodium hydroxide, 125g mannitol and 0.43g PAR (4-(2-pyridyl azo)-resorcinol) and dissolve in 1000ml water, mix with a spoon.
2.11 Blunt standard solution
2.11.1 Weigh 0.1000g metallic bismuth (Purity above 99.95%, pre-mill off the oxide film with nitric acid (1+9), then wash with water and anhydrous ethanol, and air-dry), place in a 200ml beaker, add 20ml nitric acid (2,1), dissolve in warm water, cool, transfer to a 100ml volumetric flask, add 40ml nitric acid (2.1), dilute to scale with water, mix: 1ml of this solution contains 100g bismuth 2.11.2 Transfer 50.00ml of sharp standard solution (2.11.1) to a 500ml volumetric flask, add 50ml nitric acid (2.1): dilute to scale with water, mix, this solution 1ml contains 10u bismuth 2.11. Transfer 25.00ml of bismuth standard solution (2.11.2) to a 25(ml volumetric flask, Add 25ml nitric acid (2.1), dilute to the mark with water and mix. This solution contains 1ml of bismuth. Approved by the Ministry of Metallurgical Industry on March 31, 1987
Implementation on March 1, 1988
3 Instruments
GB4702.12--87
Oscillographic polarograph. The dropping mercury electrode is the working electrode and the saturated calomel electrode is the reference electrode. The platinum electrode is the auxiliary electrode4 Sample
All samples should pass through a 1.68mm sieve.
5 Analysis steps
5.1 Sample quantity
Weigh 0.5000g of sample.
5.2 Blank test
Carry out a blank test with the sample||tt ||5.3 Determination
5.31 Place the sample (5.1) in a 15ml beaker, cover with 1 table blood and add 15ml hydrochloric acid (2.2). Heat on a low-temperature electric hot plate 1 until the sample is completely dissolved, remove, add 15ml ammonium citrate solution (2.4), 5ml EDTA solution (2.5), mix well, and heat on a low-temperature electric hot plate for 2~3min, remove, and cool to temperature. 5.3.2 Add 8ml ammonium nitrate (2.6), mix well, transfer the solution to a 125ml separatory funnel, wash the beaker with 10~15ml water, put it in the separatory funnel, add 5ml copper reagent solution (2.7), mix well 5.3.3 In the separatory funnel, add 10ml chloroform (2. 8), shake for 1min, let stand for stratification, transfer the organic phase to another separatory funnel, repeat the extraction once, combine the organic phases 5,3.4 Add 20ml ammonia washing solution (2.9) to the organic phase, shake for 1min, let stand for stratification, transfer the organic phase to another separatory funnel filled with 20ml hydrochloric acid (2.3), shake for 1min, let stand for stratification, discard the organic phase, and transfer the aqueous phase to a 50ml beaker. 5.3.5 Steam the beaker containing the aqueous phase on a low-temperature electric heating plate until it is almost dry, add 2ml hydrochloric acid (2.2) to dissolve its pad, add 10ml base solution (2.10), transfer it to a 25ml volumetric flask, dilute to the mark with water, and mix well. Pour into the electrolytic cup and measure it by cathode derivative scanning on the oscillographic polarograph. The starting potential is -(.40V. Measure the peak height of bismuth at a potential of -0.65V and the peak height of the blank solution. 5. Preparation of bismuth standard comparison solution and measurement of bismuth peak height Take three portions of bismuth standard solution (2.11) with a bismuth content similar to that in the sample amount (5.1), add the same amount of bismuth-free metal as the sample amount (5.1) respectively, and follow the steps below according to 3.3.1 to 5.3.5. 6 Calculation of analysis results Calculate the bismuth content according to the following formula, Bi (%) =
Wherein: is the key peak height of the bismuth standard comparison solution minus the blank, grid hole—the peak height of bismuth in the test solution minus the blank, grid: m,—the amount in the standard comparison solution, g:
mo—the amount of sample, g.
Tolerance
The difference in the analysis results between laboratories should not be greater than the allowable difference listed in the following table, additional instructions:
>0. 0003 ~0. 0010
>0.0010~0.9015
This standard was drafted by Hunan Ferroalloy Factory. GB 4702.12—87
0,0002
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB582-65 "Metallic Chromium Chemical Analysis Method" will be invalid. This standard promotes the level grade mark GB4702.12—87I.
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