GOST 24018.2-80
GOST 24018.2−80 heat-resistant Alloys on a Nickel basis. Methods for determination of antimony (with Amendments No. 1, 2)
GOST 24018.2−80
Group B39
INTERSTATE STANDARD
ALLOYS HIGH-TEMPERATURE NICKEL-BASED
Methods for determination of antimony
Nickel-based fire-resistant alloys.
Methods for the determination of antimony
ISS 77.120.40
AXTU 0809
Date of introduction 1981−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of metallurgy of the USSR
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
The number of the paragraph, subparagraph |
| GOST 200−76 |
4.2 |
| GOST 849−97 |
2.2 |
| GOST 1089−82 |
2.2, 3.2, 4.2 |
| GOST 3118−77 |
2.2, 3.2 |
| GOST 3760−79 |
3.2 |
| GOST 4197−74 |
2.2, 3.2, 4.2 |
| GOST 4204−77 |
2.2, 3.2 |
| GOST 4461−77 |
2.2, 3.2 |
| GOST 4520−78 |
3.2, 4.2 |
| GOST 4658−73 |
4.2 |
| GOST 5456−79 |
3.2 |
| GOST 5789−78 |
2.2 |
| GOST 5817−77 |
3.2 |
| GOST 5962−67 |
2.2, 3.2 |
| GOST 6552−80 |
3.2. 4.2 |
| GOST 6691−77 |
2.2, 3.2, 4.2 |
| GOST 9293−74 |
4.2 |
| GOST 11125−84 |
2.2, 3.2, 4.2 |
| GOST 14261−77 |
2.2, 3.2, 4.2 |
| GOST 14262−78 |
2.2, 3.2 |
| GOST 18300−87 |
2.2, 3.2 |
| GOST 19522−74 |
3.2 |
| GOST 20015−88 |
3.2, 4.2 |
| GOST 22159−76 |
4.2 |
| GOST 24018.0−90 |
1.1 |
| GOST 24147−80 |
3.2 |
5. Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)
6. EDITION (August 2004) with Changes No. 1, 2 approved in December 1985, December 1990 (IUS 4−86, 3−91)
This standard specifies the extraction-photometric method for the determination of antimony (in mass fraction of from 0.0002% to 0,010%), extraction-photometric method for the determination of antimony (in mass fractions of from 0.0005% to 0,010%) and Stripping voltammetric method for the determination of antimony (in mass fractions of from 0.0001% to 0.005%).
(Changed edition, Rev. N 2).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 24018.0.
2. EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF ANTIMONY IN ALLOYS WITH A MASS FRACTION OF NOT MORE THAN 3% OF TUNGSTEN AND NOT MORE THAN 3% TITANIUM
2.1. The essence of the method
The method is based on the interaction of the anion hexachloroantimonate with brilliant green in the medium of sulfuric and hydrochloric acids with the formation painted in blue-green color of the compound is extracted with toluene.
The optical density of the extract is measured on a spectrophotometer at a wavelength of 640 nm or photocolorimeter in the field of light transmission from 610 to 700 nm.
(Changed edition, Rev. N 2).
2.2. Apparatus, reagents and solutions
Spectrophotometer or photoelectrocolorimeter.
Hydrochloric acid according to GOST 3118, GOST 14261 and diluted 1:1, 1:5.
Nitric acid according to GOST 4461, GOST 11125 and diluted 1:1.
Sulfuric acid according to GOST 4204, GOST 14262 and diluted 1:1, 1:4, 1:10.
A mixture of hydrochloric and nitric acids: the 150 cmof hydrochloric acid pour 50 cm
of nitric acid and stirred, and the mixture diluted 1:1, prepared immediately before use.
Sodium atomistically according to GOST 4197, a solution with a mass concentration of 10 g/cm, (g/DM
).
Carbamide (urea) GOST 6691, saturated solution: 100 g of urea dissolved in 100 cmof hot water, cool.
Tin dichloride 2-water, a solution with a mass concentration of 25 g/cm, (g/DM
) in hydrochloric acid (1:5).
Ethyl alcohol according to GOST 5962* or GOST 18300.
________________
* On the territory of the Russian Federation GOST R 51652−2000 (here and below).
Brilliant green solution with a mass concentration of 0.5 g/cm(g/DM
):
0.5 g of brilliant green are dissolved in 25 cmof ethanol, transferred to a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Toluene according to GOST 5789.
Antimony grades of Su00, Su000, Su0000, Su00000 according to GOST 1089.
Standard solutions of antimony.
Solution a: 0,10 g of metallic antimony is dissolved in 30 cmof sulfuric acid under heating, cooled. The solution was transferred to a volumetric flask with a capacity of 1 DM
containing 400 cm
of sulphuric acid (1:4). The solution was cooled, made up to the mark with water and mix.
1 cmstandard solution contains 0.0001 g of antimony.
Solution B: 10 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm
, top up with sulphuric acid (1:10) to the mark and mix.
The solution is prepared immediately before use.
1 cmstandard solution B has the 0.00001 g of antimony.
Solution: 10 cmstandard solution B is transferred to a volumetric flask with a capacity of 100 cm
, top up with sulphuric acid (1:10) to the mark, mix, prepared immediately before use.
1 cmstandard solution contains 0,000001 g of antimony.
(Amended
, Edit. N 1, 2).
2.3. Analysis
2.3.1. The weight of the alloy (tab.1) were placed in a glass (or flask) with a capacity of 250−300 cm, pour 15−20 cm
of a mixture of hydrochloric and nitric acids and 5 cm
of sulfuric acid. A glass cover glass and the sample is dissolved with moderate heating. The solution was evaporated prior to the allocation of steams of sulfuric acid and cooled.
Table 1
| Mass fraction of SB, % |
The weight of the portion of the alloy, g |
The volume of solution after dilution, see |
The volume aliquote part of the solution, cm |
The weight of the portion of alloy, suitable aliquote part of the solution, g |
| From 0,0002 to 0,001 incl. |
0,5 |
- |
All |
0,5 |
| SV. 0,001 «0,0025 « |
0,25 |
- |
All |
0,25 |
| «Of 0.0025» to 0.005 « |
0,25 |
50 |
20 |
0,1 |
| «0,005» 0,01 « |
0,25 |
50 |
10 |
0,05 |
When the mass fraction of antimony from from 0.0002% to 0.0025% to the content of the beaker was added 15 cmof hydrochloric acid (1:1), gently warmed to dissolve the salts, and cooled. Then pour the portions 1−3 cm
of a solution of tin dichloride (until full recovery of iron), 2−4 cm
attestatio solution of sodium (until the establishment of the unchanging color of the solution), and, periodically stirring the solution, let it stand for 3 min. To the solution poured 1 cm
of a saturated solution of urea, stirred and poured it into a separatory funnel with a capacity of 250 cm
. Then add 50−60 cm
of water (to the volume of the aqueous phase 80−90 cm
), 15 drops (0.5 cm
) of a solution of brilliant green, 10 cm
of toluene, and then with the contents of the funnel vigorously shaken for 1 min. the Toluene and water layers are allowed to settle for 0.5 min, the aqueous layer discarded and the toluene is filtered off through cotton wool in a cuvette layer thickness of 10 mm, cuvette, close lid and 30 min, measure the optical density of the solution on the spectrophotometer at
When the mass fraction of antimony from 0,0025% to 0.01% to the content of the beaker was added 15 cmof hydrochloric acid (1:1), gently warmed to dissolve the salts, and cooled. The solution was transferred to a volumetric flask with a capacity of 50 cm
, add hydrochloric acid (1:1) to the mark and mix. Aliquot part of the solution (table.1) is placed in a beaker or flask with a capacity of 100−150 cm
, add 3 cm
of sulphuric acid (in the case of aliquote parts of a solution of 20 cm
), or 4 cm
of sulphuric acid (in the case of aliquote part 10 cm
), pour the 1−3 cm
tin dichloride, and further analysis is carried out as described above.
(Changed edition, Rev. N 1, 2).
2.3.2. Construction of calibration curve
In five of the six beakers (or flasks) with a capacity of 250−300 cmpoured the sequence 1, 2, 3, 5, 7 cm
standard solution Into antimony.
From the values of optical density of analyzed solutions is subtracted the value of optical density in the reference experiment. The found values of optical density of solutions and their corresponding masses of antimony building a calibration curve.
(Changed edition, Rev. N 1, 2).
2.4. Processing of the results
2.4.1. Mass fraction of antimony () in percent is calculated by the formula
where is the mass of antimony, was found in the calibration schedule g;
— the weight of the portion of alloy, suitable aliquote part of the solution,
(Changed edition, Rev. N 1).
2.4.2. The absolute differences of the results of the parallel definitions should not exceed (at p = 0.95) of permissible values, specified in table.3b.
(Changed edition, Rev. N 2).
3. EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF ANTIMONY IN ALLOYS WITH A MASS FRACTION OF MORE THAN 3% OF TUNGSTEN AND MORE THAN 3% TITANIUM
3.1. The essence of the method
The method is based on reaction of interaction of the anion of antimony (SbCl) with methylene blue in the medium of 4 mol/DM
sulphuric and 1 mol/DM
of hydrochloric acid with the formation of the complex compound, colored blue, extracted with chloroform, or with a brilliant green in the medium of sulfuric and hydrochloric acid with the formation of the complex compound, painted in blue-green color is extracted with toluene. Maximum light absorption of the solution is observed at
(Changed edition, Rev. N 2).
3.2. Apparatus, reagents and solutions
Spectrophotometer, photoelectrocolorimeter, or spectropolarimeter.
Thermometer.
Hydrochloric acid according to GOST 3118, GOST 14261 and diluted 1:5.
Nitric acid according to GOST 4461, GOST 11125 and diluted 1:15.
Sulfuric acid according to GOST 4204, GOST 14262 and diluted 1:1, 1:4, 1:10.
Mixture of nitric and hydrochloric acids: the 150 cmof hydrochloric acid pour 50 cm
of nitric acid and mix; dilute 1:1, prepared immediately before use.
Orthophosphoric acid according to GOST 6552.
Tartaric acid according to GOST 5817, a solution with a mass concentration of 50 g/cm, (g/DM
).
Ammonia water according to GOST 3760, GOST 24147.
Ammonium radamisty according to GOST 19522, solution with a mass concentration of 5 g/cm, (g/DM
).
The thioacetamide solution with a mass concentration of 2 g/cm(g/DM
).
Sodium atomistically according to GOST 4197, a solution with a mass concentration of 10 g/cm, (g/DM
).
Carbamide (urea) GOST 6691, saturated solution: 100 g of urea dissolved in 100 cmof water, cool.
Tin dichloride solution with a mass concentration of 25 g/cm, (g/DM
) in hydrochloric acid, diluted 1:5.
Hydroxylamine hydrochloride according to GOST 5456.
Methylene blue aqueous solution with a mass concentration of 0.1 g/cm(g/DM
).
Ethyl alcohol according to GOST 5962, GOST 18300.
Brilliant green solution with a mass concentration of 0.5 g/cm(g/DM
):
0.5 g of brilliant green are dissolved in 25 cmof ethanol, transferred to a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Chloroform according to GOST 20015.
Universal indicator paper pH 1−10.
Mercury (II) nitrate according to GOST 4520 solution with a mass concentration of 1 g/cm(g/DM
):
1 grams of mercury nitrate are dissolved in 80 cmof nitric acid (1:15). The solution was transferred to a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Antimony grades of Su00, Su000, Su0000, Su00000 according to GOST 1089.
Standard solutions of antimony.
Solution a: 0,10 g of metallic antimony is dissolved in 30 cmof sulfuric acid when heated and cooled. The solution was transferred to a volumetric flask with a capacity of 1 DM
containing 400 cm
of sulphuric acid (1:4). The solution was cooled, made up to the mark with water and mix.
1 cmstandard solution contains 0.0001 g of antimony.
Solution B: 10 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm
, top up with sulphuric acid (1:10) to the mark, mix, prepared immediately before use.
1 cmstandard solution B has the 0.00001 g of antimony.
Solution: 10 cmstandard solution B is placed in a volumetric flask with a capacity of 100 cm
, top up with sulphuric acid (1:10) to the mark, mix, prepared immediately before use.
1 cmstandard solution contains 0,000001 g of antimony.
(Modified
Naya edition, Rev. N 1, 2).
3.3. Analysis
3.3.1. The weight of the alloy (tab.3) is placed in the beaker (or flask) with a capacity of 250−300 cm, 30 cm, pour the
mixture of hydrochloric and nitric acids, 5 cm
of sulfuric acid. A glass (or flask) cover watch glass, and dissolve a portion with a moderate heat. The solution was evaporated prior to the allocation of sulfuric acid vapor, is cooled. The contents of the beaker (or flask) pour 50 cm
of water, 20 cm
of a solution of tartaric acid and heat the solution for 10 min to dissolve the salts. Adding 20−30 cm
of ammonia solution to obtain pH 8−9 by universal indicator and heated to dissolution of tungsten acid. The solution is poured hydrochloric acid to pH 2 by universal indicator and the excess 7.5 cm
. Solution top up with water to about 150 cm
and heated to boiling.
Table 3*
___________________________
* Table.2. (Deleted, Rev. N 2).
| Mass fraction of SB, % |
The mass of the alloy, g |
| From 0.0005 to 0.004 incl. |
0,5 |
| SV. 0,004 «0,008 « |
0,25 |
| «To 0.008» to 0.01 « |
0,20 |
Carefully add 1−2 g of hydroxylamine hydrochloride, and boil the solution until complete reduction of iron (by the reaction with ammonium radamisty).
Add 10 cmof a solution of thioacetamide, the solution is kept at a temperature of 90 °C — 95 °C for 10 min, then add 1 cm
of solution of nitrate of mercury and 10 cm
of a solution of thioacetamide. The solution with precipitated sediment sulphides incubated 30−40 min at a temperature of 85 °C — 90 °C and left at room temperature. After 2 h, the precipitate filtered off sulphides 2 medium density filter (white ribbon) and washed 6−7 times with water. The filtrate is discarded. The filter cake was dissolved in three portions (10−15 cm
) of a hot mixture of hydrochloric and nitric acids (1:1), collecting the solution in a beaker or flask, in which was the deposition of sulphides. The filter was washed 3−4 times with hot water, adding the wash liquid to the main filtrate. Then do as indicated in the claims.3.3.2
(Changed edition, Rev. N 2).
3.3.2. Definition of antimony with methylene blue
To the filtrate poured 6 cmof sulfuric acid, cover the beaker (or flask) watch glass, and evaporate the solution until the appearance of sulphuric acid fumes and cooled.
The contents of the beaker (or flask) pour 6 cmof water, heated to dissolve the salts and poured 3 cm
of hydrochloric acid. The solution was cooled, poured 1 cm
of a solution of chloride of tin, mix. Then add 3 cm
of a solution of sodium attestatio and, periodically stirring the solution, allow solution to stand for 3 min. Pour 1 cm
of urea solution, 1 cm
of phosphoric acid, mix the solution and transfer it into separating funnel capacity of 250 cm
. The solution is poured water to a volume of 30 cm
, 0.5 cm
of a solution of methylene blue, 30 cm
of chloroform, after which the funnel is shaken vigorously for 1 min. Chloroform and water layers are allowed to settle for 30 s. the Chloroform layer was filtered through cotton wool, transferred to a cuvette layer thickness of 10 mm and measure the optical density of the solution on the spectrophotometer at
(Changed edition, Rev.
N 1).
3.3.3. Construction of calibration curve with the methylene blue
In five of the six beakers (or flasks) poured successively 2, 5, 10, 15, 20 cmstandard solution Into antimony. The sixth glass is used for the reference experiment. All beakers or flasks go for 30 cm
of a mixture of hydrochloric and nitric acids, 5 cm
of sulfuric acid, cover the cups (or flasks) watch glass, heated to complete dissolution of Nickel was evaporated until the appearance of sulphuric acid fumes and cooled. The contents of the beakers (or flasks) is added to 50 cm
of water, 20 cm
of a solution of tartaric acid and heat the solution for 10 min. Then do as stated in the PP.3.3.1,
From the values of optical density of analyzed solutions is subtracted the value of optical density in the reference experiment.
The found values of optical density and corresponding mass of antimony building a calibration curve.
(Changed edition, Rev. N 1, 2).
3.3.4. To the filtrate poured 5 cmof sulfuric acid, cover the beaker or the flask with a watch glass, and evaporate the solution to start the selection of vapors of sulfuric acid and cooled.
The contents of the beaker or flask, add 15 cmof hydrochloric acid (1:1), gently warmed to dissolve the salts, and cooled.
When the mass fraction of antimony from from 0.0002% to 0.001% then use all the resulting solution.
When the mass fraction of antimony from 0.001% to 0.01% solution transferred to a volumetric flask with a capacity of 50 cm, add hydrochloric acid (1:1) to the mark and mix. Aliquot part of the solution is equal to 20 cm
, placed in a glass or flask with a capacity of 100−150 cm
, add 3 cm
of sulphuric acid, cool.
The contents of the beaker or flask, obtained in both cases, poured, with stirring, 1 cmdichloride of tin, 3 cm
of a solution of sodium attestatio and, periodically stirring the solution, allow solution to stand for 3 min.
Pour 1 cmof the urea solution, mixed and poured the solution into the separatory funnel with a capacity of 250 cm
. The solution is poured with 50−60 cm
of water (to the volume of the aqueous phase 80−90 cm
), 15 drops (0.5 cm
) of a solution of brilliant green, 10 cm
of toluene, after which the funnel is shaken vigorously for 1 min. the Toluene and water layers are allowed to settle for 30 s, the water layer discarded and the toluene is filtered off through cotton wool in a dry volumetric flask with a capacity of 25 cm
, close the glass tube with cone after 30 min, measure the optical density of the solution in a cuvette with a layer thickness of 10 mm on spectrophotometer at
640 nm or photoelectrocolorimeter with a filter having a region of light transmission in the range of wavelengths from 610 to 700 nm. As a comparison, using a solution of toluene. Mass of antimony found by the calibration graph with amendments, the control
wow experience.
3.3.5. Construction of calibration curve with diamond green
In five of the six beakers or flasks poured sequentially 1, 2, 4, 6, 8 cmstandard solution Into antimony. The sixth beaker or flask serves for the control experience. All beakers or flasks add 30 cm
of a mixture of hydrochloric and nitric acids, 5 cm
of sulfuric acid, cover the cups or flasks, watch glasses and evaporated until the appearance of sulphuric acid fumes and cooled. The contents of beakers or flasks add 50 cm
of water, 20 cm
of a solution of tartaric acid and heat the solution for 10 min. Then do as stated in the PP.3.3.1,
From the values of optical density of analyzed solutions is subtracted the value of optical density in the reference experiment.
According to the obtained values of optical density and corresponding mass of antimony building a calibration curve.
3.3.4,
3.4. Processing of the results
3.4.1. Mass fraction of antimony () in percent is calculated by the formula
where is the mass of antimony, was found in the calibration schedule g;
— the weight of the portion of the alloy or the weight of the portion of alloy, suitable aliquote part of the solution,
3.4.2. The absolute discrepancies in the results of parallel measurements (at p = 0.95) must not exceed the permissible values given in table.3b.
3.4.1,
4. INVERSION-VOLTAMMETRIC METHOD FOR THE DETERMINATION OF ANTIMONY IN ALLOYS NOT CONTAINING TUNGSTEN
4.1. The essence of the method
The method is based on the preconcetration of antimony on a stationary mercury drop electrode or the surface of a mercury-graphite electrode at a potential of minus 0.45 V in a solution of 1 mol/DMof hydrochloric acid with the subsequent registration of the current of anodic dissolution of antimony at a potential of minus 0.15 V against the bottom of mercury.
Antimony pre-separated by extraction with chloroform in the environment 4 mol/DMsulphuric and 1 mol/DM
hydrochloric acid in a compound hexachloroantimonate with methylene blue.
4.2. Apparatus, reagents and solutions
Polarograph AC or oscilloscope, or DC.
The polarographic cell with the anode of the bottom with mercury.
A stationary mercury drop electrode of any design, providing the required accuracy of reproducibility of the analytical signal.
Or a solid electrode (4 mm
) from graphitemoderated material of any method of construction, used in the mercury-graphite providing the required accuracy of reproducibility of the analytical signal.
Mercury brands r0 and Р00 according to GOST 4658 containing no moisture.
Nitrogen gas according to GOST 9293.
Hydrochloric acid according to GOST 14261, diluted 1:5 and a solution of 1 mol/DM.
Nitric acid according to GOST 11125 and diluted 1:15.
Sulfuric acid according to GOST 14262 and diluted 1:4 and 1:10.
Orthophosphoric acid according to GOST 6552.
Tin dichloride solution 25 g/100 cmin hydrochloric acid 1:5.
Sodium atomistically according to GOST 4197, a solution of 10 g/100 cm.
Carbamide (urea) GOST 6691, a solution of 50 g/100 cm.
Methylene blue, an aqueous solution of 0.1 g/100 cm.
Chloroform according to GOST 20015.
Hydrazine hydrochloric acid according to GOST 22159.
Sodium posterolaterally (hipofosfit sodium) according to GOST 200, a solution of 50 g/100 cm.
Mercury (II) nitrate oxide according to GOST 4520, a solution of 0.1 g/100 cm: 0.1 g of mercury nitrate are dissolved in 80 cm
of nitric acid (1:15). The solution was transferred to a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Antimony grades of Su00, Su000, Su0000, Su00000 according to GOST 1089.
Standard solutions of antimony.
Solution a: 0,10 g of antimony dissolved in 20 cmof sulfuric acid when heated and cooled. The solution was transferred to a volumetric flask with a capacity of 1 DM
containing 400 cm
of sulphuric acid (1:4). The solution was cooled, made up to the mark with water and mix.
1 cmstandard solution contains 0.0001 g of antimony.
Solution B: 10 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm
, top up with sulphuric acid (1:10) to the mark, mix, prepared immediately before use.
1 cmstandard solution B has the 0.00001 g of antimony.
Solution: 2.5 cmstandard solution B is placed in a volumetric flask with a capacity of 50 cm
, made up to the mark with water and mix is prepared immediately before use.
1 cmstandard solution contains 0,00
00005 g of antimony.
4.3. Analysis
4.3.1. A sample of alloy weighing 0.25 g were placed in a glass with a capacity of 250 cm, flow 15 cm
of hydrochloric acid and 5 cm
of nitric acid and 6 cm
of sulphuric acid, the beaker cover watch glass, and dissolve a portion with a moderate heat. The solution was evaporated prior to the allocation of sulfuric acid vapor, is cooled. The contents of the glass pour 6 cm
of water, heated to dissolve the salts and poured 3 cm
of hydrochloric acid. The solution was cooled, poured 1−2 cm
tin dichloride to a complete reduction of iron (III), 2−4 cm
solution azotistykh sodium to extinction by the brown color of the solution after 3 min. add 2 cm
of a saturated solution of urea and 1 cm
of phosphoric acid. The solution was transferred to a separatory funnel with a capacity of 250 cm
, add water to a volume of 30 cm
, 10 drops (0.5 cm
) of a solution of methylene blue, mix, add 30 cm
of chloroform, and then with the contents of the funnel vigorously shaken for 1 min. the Organic and aqueous layers allowed to settle for 30 s. the Chloroform layer is drained into a glass, where he carried out the dissolution of the weighed portion of sample, add 2 cm
of sulphuric acid, 5 cm
of nitric acid and evaporated to release vapors of sulfuric acid, cooled, wash the side of the Cup with water and evaporate the solution to wet salts.
Then add 2.5 cmof hydrochloric acid of 5 cm
of water, is heated under the glass to dissolve the salts, transferred to a volumetric flask with a capacity of 25 cm
by diluting with water up to 15−20 cm
.
When working with a stationary mercury drop electrode into volumetric flask add 2cmof a solution of hypophosphite sodium, made up to the mark with water and mix.
In a polarographic cell poured 20−25 cmof solution of 1 mol/DM
of hydrochloric acid, previously purged with nitrogen for 5 min, add aliquot part of a researched solution in accordance with the table.3A and the solution is mixed, including the mixer.
Table 3A*
___________________________
* Table.4. (Deleted, Rev. N 2).
| Mass fraction of SB, % |
The volume aliquote part of the solution, cm |
The weight of the portion of the sample corresponding to aliquote part of the solution, g |
| From 0.0001 to 0.0005 to incl. |
2 |
0,02 |
| SV. Of 0.0005 «0,0025 « |
1 |
0,01 |
| «0,0025» 0,0050 « |
0,5 |
0,005 |
Set on polarography potential minus the 0.45 V and the electrolysis is carried out for 2 min in stirred solution. At the end of the accumulation time, stop stirring, allow the grout to settle down with the register 15 and the anodic polarization curve with linearly varying electrode potential from minus 0.45 V to minus 0.05 V. Maximum current of antimony observed at a potential of minus 0.15 V relative to the bottom of mercury. For each dimension, get a new drop of mercury.
When working with mercury-graphite electrode.
Just before polarographically added to volumetric flask 0.5 g of hydrazine chloride and boil in water bath for 1−2 min. Then solution was cooled, made up to the mark with water and mix.
In a polarographic cell, pour the 20−25 cmof a hydrochloric acid molar concentration of 1 mol/DM
, pre-purged with nitrogen for 5 min, add 3−4 drops of solution of nitrate of mercury and aliquot part of the study solution (table 3A) depending on the assumed mass fraction of antimony in the analyzed sample.
Set on polarography potential minus the 0.45 V and spend the concentration of antimony in mercury-graphite electrode in a continuously stirred solution for 2 min.
At the end of time electroconnection stop stirring and allow solution to settle down 15, and then remove the anodic polarization curve with linearly varying electrode potential from minus 0.45 V to + 0.2 V, registering a peak of dissolution of antimony at a potential of minus 0.15 V. After each measurement is carried out electrochemical cleaning of the electrode at a potential of plus 0.2 V in a stirred solution for 30 s. Check the polarization curves is repeated three times, the first measurement in the calculations is not taken into account.
The sensitivity of the device are selected so that the height of the recorded peak was at least 10 mm.
4.3.2. Mass fraction of antimony with the stationary mercury drop electrode is calculated according to the calibration schedule.
To build a calibration curve in the beakers (or flasks) with a capacity of 250 cmflow: 1, 2, 5 cm
solution; 0.5, 1 cm
of solution B; at 15 cm
of hydrochloric acid and 5 cm
of nitric acid, 6 cm
of sulfuric acid and then do as in step
Simultaneously conduct control experience for antimony in the reagents.
Mass fraction of antimony when working with mercury-graphite electrode find the method of standard additions.
Aliquot part of the standard solution added to the solution, stirred for 30 s and then spend electroconnection of antimony as described in Chapter
The value of the standard additives are selected so that the height of the peak of antimony after adding the additive increased 1.5−2 times.
Simultaneously conduct control experience for antimony in the reagents.
4.4. Processing of the results
4.4.1. Mass fraction of antimony () in percentage by the method of additions described by the formula
where is the height of the peak of the antimony with polarography of test solution, mm;
— the height of the peak of the antimony with polarographically solution in the reference experiment, mm.
— the height of the peak of antimony after administration to the cell of standard addition, mm;
— the volume of standard addition, cm
;
— mass concentration of a standard solution, g/cm
;
— the weight of the portion of alloy, suitable aliquote part of the solution,
Mass fraction of antimony () in % according to the calibration schedule is calculated by the formula
where is the mass of antimony, was found in the calibration schedule g;
— the weight of the portion of alloy, suitable aliquote part of the solution,
4.4.2. The absolute differences of the results of the parallel definitions should not exceed permissible values at p = 0.95 as shown in table.3b.
Table 3b
| Mass fraction of SB, % |
The absolute allowable difference, % |
| 0.0001 0.0002 incl. |
0,0001 |
| SV. Of 0.0002 «to 0.0005 « |
0,0002 |
| «Of 0.0005» to 0.001 « |
0,0003 |
| «Of 0.001» to 0.002 « |
0,0005 |
| «Of 0.002» to 0.005 « |
0,001 |
| «0,005» 0,01 « |
0,002 |
Section 4. (Added, Rev. N 2).
