GOST 12645.12-86

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  ГОСТ 12645.12-86

GOST 12645.12−86 indium. Method for the determination of tellurium (with Change No. 1)

GOST 12645.12−86*

Group B59

STATE STANDARD OF THE USSR

INDIUM

Method for the determination of tellurium

Indium.
Method for determination of tellurium

AXTU 1709

Date of introduction 1988−01−01

Resolution of the USSR State Committee for standards from 23.10.86 N 3188 date of introduction is established 01.01.88

Limitation of actions taken on the Protocol, the Interstate Council for standardization, Metrology and certification (ICS 2−93)

* REISSUE (March 1998) with amendment No. 1, approved in June 1996 (IUS 9−96).

Change N 1 GOST 12645.12−86 adopted by the Interstate Council for standardization, Metrology and certification by correspondence 15.04.94 (report of the Technical Secretariat N 2)

The adoption voted:

1a. SCOPE

This standard sets the polarographic method for the determination of tellurium (if the mass fraction of tellurium from 5·10to 5·10%) in India brand Ying 000.

The method is based on the recovery of tellurium to the elemental state, the coprecipitation in the environment of hydrochloric acid hydroxylamine and Chernovetskiy sodium with amorphous sulfur and polarographic determination in the acidic solution of KCl at a potential of minus 0.8 V (saturated calomel electrode) using a stationary mercury electrode.

(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 standard addition according to GOST 12645.11−86.

As a Supplement, use a solution of tellurium in a concentration of 1 µg/cmprepared on polarographic background of the day of application.

(Changed edition, Rev. N 1).

2. SAFETY REQUIREMENTS

2.1. Safety requirements — according to GOST 12645.10−86.

3. APPARATUS, REAGENTS AND SOLUTIONS

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. The anode compartment above the mercury is filled with saturated solution of potassium chloride.

Pipettes according to GOST 29227−91 with a capacity of 0.1 and 0.2 cm.

Quartz glasses according to GOST 19908−90 with a capacity of 50 and 100 cm.

Quartz tubes according to GOST 19908−90 with a capacity of 15 cm.

Nitric acid GOST 4461−77 distilled.

Hydrochloric acid by the GOST 3118−77, distilled and diluted 1:20.

Hydrochloric acid, 8 mol/DM, prepared by saturation with bidistilled water hydrogen chloride.

Formic acid according to GOST 5848−73.

Sulfuric acid GOST 4204−77, diluted 1:1.

Hydroxylamine hydrochloride according to GOST 5456−79, solution 100 g/lto 8 mol/DMhydrochloric acid.

The washing liquid in a flask with a capacity of 1 DMwas placed 100 g of hydroxylamine hydrochloride, poured 50 cm8 mol/DMof hydrochloric acid, made up to 1 DMwith bidistilled water and stirred.

Sodium thiosulfate crystal according to GOST 244−76, solution 100 g/l; prepared from recrystallized reagent.

Potassium permanganate according to GOST 20490−75.

Potassium chloride according to GOST 4234−77, a saturated solution, prepared with bidistilled water.

Bromine according to GOST 4109−79.

Salt is the disodium Ethylenediamine — N, N, N', N' — tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73.

Background polarographic; prepared as follows: 200 g of potassium chloride and 1 g Trilon B dissolved in 1 DMof double-distilled water, the acidity of the background was adjusted to pH 2,8 (universal indicator paper), distilled with hydrochloric acid, diluted 1:20.

Distilled water GOST 6709−72, is further distilled in a quartz apparatus with addition of potassium permanganate.

Tellurium brand T-B4.

Mercury GOST 4658−73.

Standard solutions of tellurium

Solution a: 0.050 g of tellurium are dissolved in 20 cmof distilled hydrochloric acid with periodic dropwise addition of nitric acid. The solution was transferred to a volumetric flask with a capacity of 500 cm, is diluted to the mark with water and mix.

1 cmof the solution contains 100 micrograms of tellurium.

Solution B: 5 cmAnd placed in a standard measuring flask with a capacity of 500 cm, is diluted to the mark polarographic background and stirred. The solution is prepared the day of application.

1 cmof the solution contains 1 ág of tellurium.

(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 cmof nitrogen and 2 cmof hydrochloric acid and dissolve under low heat under the watch glass. The hour glass is washed with 5 cmdouble-distilled water and evaporated to dryness. Pour 5 cmwith bidistilled water and is evaporated to wet salts. Are two test experience.

To the wet residue is added dropwise formic acid (to decompose the nitrates) and carry out the removal of nitrogen oxides and formic acid in a water bath. The operation is repeated until the complete termination of allocation of yellow vapor. The residue in the beaker treated two more times with 2 cmof formic acid, which was evaporated to dryness. To the residue 3 times poured to 5 cmdouble-distilled water, each time evaporating to dryness.

The dry residue is dissolved in 10 cmof a solution of hydroxylamine hydrochloride and the solution was transferred to a test tube with a capacity of 15 cm. Add 1 cmof sodium thiosulfate, the tube was incubated for 1 h in a boiling bath. Then add another 1 cmof sodium thiosulfate, again incubated for 1 h in a water bath and left overnight. The precipitate was filtered off on paper filter «white ribbon», washed with 250−300 cmwash liquid and the same amount of water.

The precipitate from the filter washed with 10−15 cmof water in a Cup with a capacity of 50 cm, pour 1 cmof sulfuric acid solution, 0.2 cmof a saturated solution of potassium chloride, five drops of bromine. The solution was evaporated until complete removal of sulphuric acid fumes and cooled. In a glass pour 20 cmof the polarographic background, slightly warmed until complete dissolution of the residue is cooled, transferred to a volumetric flask with a capacity of 25 cm, top up to the mark and stirred in the background.

The solution was transferred to a cell with external saturation calomel anode, a mercury drop is formed, include the cell and at a potential of minus 0.60 to lead To the accumulation of tellurium in 2−3 min. When shooting polarogram use cathode scan voltage. The peak potential of tellurium -0.8 V. Polarogram of each solution is removed at least three times. Similarly we proceed with the registration of tellurium in the samples with additives when conducting control experiments.

The height of the peak of tellurium 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 tellurium 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 tellurium () in percent is calculated by the formula

,

where is the mass of additives of tellurium, mcg;

 — the height of the peak of tellurium in the sample minus the average value of the amendment in the reference experiment, mm.

 — the height of the peak of the tellurium 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 between the results of two parallel measurements and between the results of two tests at a confidence level of 0.95, should not exceed the values given in the table.

Permitted discrepancies for the intermediate grades of tellurium find using linear interpolation.