GB/T 4324.1-1984 Chemical analysis method for tungsten - Continuous determination of lead and cadmium by square wave polarography GB/T4324.1-1984 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of tungsten
Methods for chemical analysis of tungstenThe sqaarewave polarographic method forthe successive determination of leadand cadmium contents
UDC 669.2T :543.
.253:546.815
GB 4824.1-84
This standard is applicable to the determination of tungsten powder, tungsten bar, tungsten trioxide, tungsten trioxide, lead ammonium paratungstate and copper contents. Determination range: 0.00005~0.0030%c
This standard complies with GB1467-78 "General Principles and General Provisions of Metallurgical Product Chemical Analysis Method Standards" 1 Method Summary
The sample is decomposed with sulfuric acid-ammonium sulfate, and the main calcium is complexed with citric acid. At pH 8-9, lead is extracted with dithiol-benzene solution, and square wave polarography is performed in perchloric acid-hydrochloric acid base solution 41. 2 Reagents and materials
2.1 Ammonium sulfate, high purity. If high-purity ammonium sulfate is not available, extract it according to the following method: first prepare 50% ammonium sulfate aqueous solution, adjust it to pH 8-9 with ammonium sulfate, extract it with dithiol-benzene solution, extract it repeatedly until the green color of dithiol-benzene solution remains unchanged, filter it, let it stand overnight, and absorb the supernatant.
2.2 Mercury.
2.3 Sulfuric acid (specific gravity 1.84), high purity.
Hydrochloric acid (specific gravity 1.19), extra pure,
Hydrochloric acid (1+1), extra pure.
2.6Ammonium hydroxide (1+1), extra pure.
2.7Citric acid (superior purity), solution (50%). 2.8Dithiophene extract; weigh 0.5g of dithiophene and place it in a 1000ml beaker, add 1400ml benzene to dissolve it, transfer it to a 1000ml separatory funnel, add 150ml of ammonium hydroxide (2+98) each time, shake for 2min, (repeat 4-5 times), collect the aqueous phase in a 1000ml beaker, remove the organic phase, acidify the aqueous phase with hydrochloric acid (2.5), transfer it to the original separatory funnel, extract dithiophene with 1000ml benzene several times, and combine the organic phases in a brown bottle for later use. If the sample has impurities as high as the upper limit of the technical conditions, a saturated solution of dithiophene can be used. 2.9 Ammonium citrate: Ammonium hydroxide washing solution, 1000ml solution contains 20g ammonium citrate and 5ml ammonium hydroxide (specific gravity 0.90). 2.10 Perchloric acid-hydrochloric acid base solution: Pipette 25ml perchloric acid (specific gravity 1.67, high purity) into a 10 ml volumetric flask pre-filled with 500ml water, add 1ml hydrochloric acid (1M), dilute to scale with water, mix well, and set aside. 2.11 Phenol peptide solution (0.1%): Prepare with ammonium hydroxide (2.6). 2.12 Triple distilled water (this water is used in this recipe). 2.13 Lead standard solution.
2.13.1 Weigh 0.1000g of metallic lead (99.998%), place in a 250ml beaker, add 5ml of nitric acid (1+1), heat to dissolve, evaporate to near dryness, then add 4ml of hydrochloric acid (2.4) and evaporate to dryness twice, remove all nitrogen dioxide, add 100ml of hydrochloric acid (2.5) to dissolve the lead salt, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 100μg of lead in 1ml. National Bureau of Standards 1984-04-12 Issued
1985-0301 Implementation
GB ±324.1—84
2.13.2 Transfer 10.00ml of lead standard solution (2.13.1), place in a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 1mt1μg.
2.14 Copper standard bath solution
2.14.1 Weigh 0.1000g of metallic cadmium (99.99%), place it in a 250ml beaker, add 20ml of hydrochloric acid (1+3) to dissolve, transfer to a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 100μg of cadmium per ml. 2.14.2 Transfer 10.00ml of cadmium standard solution (2.14.1), place it in a 1000ml volumetric flask, dilute to scale with water, and mix. This solution contains 1ug per ml.
Nitrogen (in steel cylinder)
Square wave polarograph: The sensitivity should not be less than 1×10-7M. The sample
The pigeon strips should be zinc powder and pass through a 120 mesh
5 Analysis steps
5. 1 Determination quantity
When analyzing, a sample should be weighed for determination. The determination value should be within the allowable difference in the room and the industry average value should be taken. 5.2 Sample quantity
Weigh the sample quantity according to Table 1.
Lead, cadmium, instrument
.0.0002
Blank wind test
Carry out the air sound test with the sample.
5. Determination
Refined, %
Sample mother·g
5.4.1Put the sample (5.2) in a 250ml beaker, add 10g ammonium sulfate (2.1) and 6ml sulfuric acid (2.3), and heat it on an electric furnace to completely dissolve it.
5.3.2 Remove the coolant, rinse the surface and the wall of the cup with water, add 8ml of citric acid solution (2.7), add 4 drops of chlorinated bath solution (2.11), adjust with ammonium hydroxide (2.6) and hydrochloric acid (2.5) until the solution turns slightly red, and add 2 drops of ammonium hydroxide (2.6) to 18-9, and cool.
Transfer the test solution to a 125ml separating funnel, dilute with water to 80tml, add 15ml of dithiothreitol-benzene extract (2.8), shake for 3min, and continue to benzene. Take several times until the organic phase remains green. 5.4.4 Combine the organic phases! In another separatory funnel, add 50 ml of ammonium citrate-ammonium hydroxide washing solution (2.9), shake for 30 seconds, discard the water, wash once more, discard the aqueous phase, add 50 ml of distilled water, shake for 15 seconds, and discard the aqueous phase. Add 2-5 ml of perfluoric acid-hydrochloric acid base solution (2.10) to the organic phase, remove with benzene, shake for 3 minutes. 5.4.5
5.4.6 Put the aqueous phase into a solution cup and pass nitrogen (2.15) for 5-10 minutes to remove nitrogen. 2
GB 4324.184
5.4.7 Use the mercury pool electrode as reference and record the polarogram between -0.35 and -0.90 V. After subtracting the blank made with the sample, draw the curve from 1 to find the corresponding lead and cadmium.
5.5 Drawing of working curve
5.5.1--Set up a 125m separating funnel, add lead and cadmium standard solutions (2.13.2 or 2.14.2) according to Table 2, add 8ml citric acid solution (2.7), 4 drops of phenolic acid solution (2.11), and use ammonium hydroxide (2.6) to adjust the solution until it becomes neutral. Slightly red, and 2 drops are added in excess. The following is carried out according to 5.4.3 (starting from diluting with water to 80 ml) to 5.4.6. 5.5.2 After subtracting the blank wave height of the reagent, use the lead and cadmium content as the horizontal axis and the wave height as the vertical axis to make a curve. Table 2
Lead and cadmium content range, road
Lead and cadmium standard solution
Lead and cadmium standard solution added amount
6 Calculation of analysis results
0.00005~0,0002
Calculate the percentage of lead according to formula (1):: 6.1
0. 0002 ~ 0.0006
Pb (%)
Where: m,——the amount of lead found from the working curve, gi the sample size, g. Www.bzxZ.net
6.2 Calculate the percentage of lead according to formula (2): Cd (%)=
Where: m2——the amount of lead found from the T working curve,; m
7 Allowable difference
-sample size, g.
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 3. 0.0006 ~0.0015
0.0015- 0.0030
Additional instructions
Lead. Cadmium
0.00005 - 0. 00020 | | tt | 4324.1—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 Factory. This standard is drafted by Zhuzhou Cemented Carbide! The main drafter of this standard is Peng Diankun,
Allowance
0n0025
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