GOST 12645.11-86
GOST 12645.11−86 indium. Method for the determination of selenium (with Change No. 1)
GOST 12645.11−86*
Group B59
STATE STANDARD OF THE USSR
INDIUM
Method for the determination of selenium
Indium. Method for determination of selenium
AXTU 1709
Date of introduction 1988−01−01
Resolution of the USSR State Committee for standards from
Limitation of actions taken on the Protocol, the Interstate Council for standardization, Metrology and certification (ICS 2−93)
* REISSUE (January 1998) with amendment No. 1, approved in June 1996 (IUS 9−96)
Change N 1 GOST 12645.11−86 adopted by the Interstate Council for standardization, Metrology and certification by correspondence
The adoption voted:
| The name of the state | The name of the national authority for standardization |
| The Republic Of Azerbaijan |
Azgosstandart |
| The Republic Of Belarus |
Gosstandart Of Belarus |
| The Republic Of Kazakhstan |
Gosstandart Of The Republic Of Kazakhstan |
| The Republic Of Moldova |
Moldovastandart |
| Russian Federation |
Gosstandart Of Russia |
| Turkmenistan |
The main state inspection of Turkmenistan |
| The Republic Of Uzbekistan |
Standards |
| Ukraine |
Gosstandart Of Ukraine |
1A. SCOPE
This standard sets the polarographic method for the determination of selenium (at a mass fraction of selenium from 
The method is based on the allocation of selenium in elemental form and arsenic separation from arsenic by coprecipitation in elemental form on the collector — sulphur and its determination by the method of inversion, alternating-current voltammetry in 0.4 M sulfuric acid solution in the presence of ions of dichromate and copper (II).
(Changed edition, Rev. N 1).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 22306−77 with the Supplement.
1.1.1. The control accuracy of the analysis carried out by the method of standard additives in accordance with GOST 25086−87.
As additives used known volume of the solution selenium concentration of 1 µg/cmprepared with a 0.8 mol/DM
hydrochloric acid in a day of application.
The procedure according to claim 4.1.
The mass of selenium in the Supplement should be 100−200% of its mass fraction in the sample.
Mass fraction of selenium in the additive is determined by difference 
where and
— the results of the analysis of the sample
and the sample with the additive
, calculated as the arithmetic mean of two parallel definitions, the differences between them should not exceed the permissible value specified in the standard.
The analysis considered accurate if the value found supplements (
where and
— the permissible discrepancy of the results of parallel measurements of selenium in the sample
and in the sample with the additive
.
(Changed edition, Rev. N 1).
2. SAFETY REQUIREMENTS
2.1. Safety requirements — according to GOST 12645.10−86.
3. APPARATUS, MATERIALS AND REAGENTS
Polarograph type AC-PPT-1 or the generic type PU-1 with the stationary mercury electrode and the cell polarography with the outer anode compartment. In the anode space above the mercury is poured a mixture containing HSO
:H
PO
:H
O=1:1:2.
Pipettes according to GOST 29227−91 with a capacity of 0.1 and 0.2 cm.
The beakers, quartz GOST 19908−90 with a capacity of 50 and 100 cm.
Tubes according to GOST 25336−82 with a capacity of 30 cm.
Quartz distillation apparatus with a capacity of 1.5−2 DM.
Distilled water GOST 6709−72 distilled in a quartz apparatus with addition of potassium permanganate.
Bath water.
Nitric acid GOST 4461−77 and distilled.
Hydrochloric acid by the GOST 3118−77, distilled, solutions of 0.8, 3 and 6 mol/land diluted 1:1 and 1:10.
A mixture of concentrated nitric and hydrochloric acids in a ratio of 3:1.
Orthophosphoric acid according to GOST 6552−80.
Sulfuric acid GOST 4204−77, diluted 1:1, 1:2 and the solution of 1.6 mol/DM, purified from traces of selenium: to 300 cm
of sulphuric acid diluted 1:1, pour 0.5 cm
of the solution servational sodium 300 g/DM
. Koagulirovat when heated sulfur precipitate is separated by decantation. The solution was evaporated until the appearance of sulphuric acid fumes.
Copper sulfate according to GOST 4165−78, a solution of 0.5 g/DM.
Sodium disodium Masakovsky, 7-aqueous solution of 20.8 g of reagent was placed in a volumetric flask with a capacity of 100 cm, made up to the mark with bidistilled water and stirred.
1 cmof solution contains 50 mg of arsenic.
Sodium posterolaterally according to GOST 200−76.
Hydroxylamine hydrochloride according to GOST 5456−79, a solution of 100 g/DM6 mol/DM
hydrochloric acid.
The washing liquid 5 g of hydroxylamine hydrochloride dissolved in 100 cm3 mol/DM
of hydrochloric acid.
Chernovetskiy sodium (sodium thiosulfate) according to GOST 27068−86, recrystallized in bidistilled water, a solution of 300 g/land sulfuric acid solution to 10 cm
of a solution of sodium servational pour 2 cm
of sulfuric acid. The solution is prepared for 1 min before use.
Sodium pyro phosphate according to GOST 342−77, recrystallized in bidistilled water.
Bromine according to GOST 4109−79.
Potassium dichromate according to GOST 4220−75, a solution of 50 g/DM.
Potassium permanganate according to GOST 20490−75.
Polarographic background: to 270 cm, and 1.6 mol/DM
sulphuric acid poured 20 cm
of a solution of potassium dichromate 5 g/DM
10 cm
of a solution of copper sulphate and stirred.
Selenium.
Mercury GOST 4658−73.
The standard solutions of selenium.
Solution a: 0,100 g of selenium is dissolved in a mixture of nitric and hydrochloric acids (3:1), pour 5 cmof sulphuric acid, is evaporated prior to the allocation of steams of sulfuric acid, cooled, poured into a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
1 cmof the solution contains 1 mg selenium.
Solution B: 5 cmstandard solution And placed in a volumetric flask with a capacity of 500 cm
, is diluted to the mark of 0.8 mol/DM
hydrochloric acid and stirred. The solution is prepared the day of application.
1 cmof solution contains 10 mcg of selenium.
Solution: 10 cmstandard solution B is placed in a volumetric flask with a capacity of 100 cm
, is diluted to the mark of 0.8 mol/DM
hydrochloric acid and stirred. The solution is prepared the day of application.
1 cmof the solution contains 1 mcg of selenium.
(Changed edition, Rev. N 1).
4. ANALYSIS
4.1. The weight India weight of 1,000 g was placed in a quartz glass with a capacity of 50 cm, pour 5 cm
of nitric acid and evaporated at low heat to dryness. The residue is dissolved in 50 cm
solution 6 mol/DM
hydrochloric acid, poured on a 0.2 cm
solutions of arsenic and copper sulphate. Conduct two test experience.
The solution is heated to 60 °C, gradually adding 6−7 g phosphonoacetate sodium. After separation of the floc solution was boiled for 20 min, leave for 2 hours in low heat, and then the precipitate was filtered off on paper filter «white ribbon». Precipitate was washed on the filter 250−300 cmof hydrochloric acid (1:10) and the same amount of water. The precipitate from the filter washed into the beaker of 10−15 cm
of water, poured 1 cm
of sulfuric and nitric acids, and evaporated to the appearance of sulphuric acid fumes.
The residue was transferred into a test tube 30 cmof a solution of hydroxylamine hydrochloride, the tube was placed in a boiling water bath, add 0.5 cm
of sulfuric acid solution servational sodium and kept solution in water bath for 3 h, adding in 30 and 60 min and at the end of the deposition of 0.3 cm
of sulfuric acid solution servational sodium. The precipitate in the test tube is left overnight.
The selenium is filtered on a paper filter «white ribbon», washed with 250−300 cmwash liquid and the same amount of water. The deployed filter is washed with jet of water in a beaker with a capacity of 50 cm
, pour 1 cm
of nitric acid, 1.5 cm
of sulphuric acid (1:1), 0.5 cm
of bromine, and after 30 min carefully evaporated to the appearance of sulphuric acid fumes. To the residue poured 1 cm
of nitric acid and 0.5 cm
of bromine and repeat the evaporation until the appearance of sulphuric acid fumes.
To the residue in the glass poured 10 cmof water, 0.2 cm
of a solution of potassium dichromate, 0.2 cm
of a solution of copper sulphate and add 100 mg of sodium pyrophosphate. Then pour 10 cm
of water, stirred, solution was transferred to volumetric flask with a capacity of 25 cm
, top up to the mark with water and mix.
The solution was transferred to a cell with an external mercuriality reference electrode, mercury drop shape include the cell and at a potential of minus 0.65 In lead accumulation of selenium in 1−3 min. When shooting polarogram use cathode scan voltage. The peak potential of selenium minus 0.9 V. Polarogram of each solution is removed at least three times. Similarly we proceed with the registration of selenium in the samples with additives and the control sample.
The peak height of selenium measured vertically, is drawn through the top of the peak to the intersection with a tangent connecting the base of the left and right branches of the peak. The height of the peaks shall not differ by more than 15−20%.
Mass fraction of selenium in the solution is determined by the method of additions.
(Changed edition, Rev. N 1).
5. PROCESSING OF THE RESULTS
5.1. Mass fraction of selenium () in percent is calculated by the formula
where is the mass of supplements of selenium, mcg;
— the height of the peak of selenium in the sample, minus the average value of the amendment in the reference experiment, mm.
— the height of the peak of selenium in the samples with the additive minus the height of the peak sample and the average value of the amendment in the reference experiment, mm.
— the weight of the portion of the sample,
The result of the analysis taking the arithmetic average of the results of two parallel measurements.
(Changed edition, Rev. N 1).
5.2. Allowable absolute difference of results of two parallel measurements and between the results of two tests at a confidence level =0.95 does not exceed the values given in the table.
| Mass fraction of selenium, % |
The absolute allowable difference, % |
5·10 |
3·10 |
1·10 |
5·10 |
2·10 |
1·10 |
4·10 |
2·10 |
1·10 |
0,2·10 |
Permitted discrepancies for the intermediate grades Selena find using linear interpolation.
