GOST 9816.2-84

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  ГОСТ 9816.2-84

GOST 9816.2−84 Tellurium technical. Methods for the determination of selenium (with Amendments No. 1, 2, 3)

GOST 9816.2−84

Group B59

STATE STANDARD OF THE USSR

TELLURIUM TECHNICAL

Methods for determination of selenium

Technical tellurium. Methods for determination of selenium

AXTU 1709

Valid from 01.07.85
before 01.07.90

The decision of the State Committee USSR on standards on June 27, 1984 N 2149 validity period is set with 01.07.85 before 01.07.90*
________________
* Expiration removed by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (I & C N 4, 1994). — Note the manufacturer’s database.


REPLACE GOST 9816.2−74


MADE: the Change in N 1, approved and put into effect by the Decree of Gosstandart of the USSR from 14.05.1986 N 1229 c 01.11.1986; Modification No. 2, approved and put into effect by the Decree of Gosstandart of the USSR from 20.12.1989 N c 3908 01.07.1990; Amendment No. 3, approved and put into force by the Order of Rosstandart from 26.11.2014 No. 1771-St c 01.09.2015

Change N 1, 2, 3 are made by the manufacturer of the database in the text IUS N 8, 1986, IUS N 3, 1990, IUS N 3, 2015

This standard specifies methods for the determination of mass fraction of selenium in the technical tellurium: extraction-photometric in the concentration range from 0.005% to 0.15%; titration in the range of concentrations from 0.15% to 2.0%.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 9816.0−84.

1A. NORMATIVE REFERENCES

This standard uses the regulatory references to the following international standards:

GOST 1770−74 laboratory Glassware measuring glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 3118−77 Reagents. Hydrochloric acid. Specifications

GOST 3652−69 Reagents. Citric acid monohydrate and anhydrous. Specifications

GOST 3760−79 Reagents. The aqueous ammonia. Specifications

GOST 4204−77 Reagents. Sulphuric acid. Specifications

GOST 4232−74 Reagents. The potassium iodide. Specifications

GOST 4328−77 Reagents. Sodium hydroxide. Specifications

GOST 4461−77 Reagents. Nitric acid. Specifications

GOST 5456−79 Reagents. Of hydroxylamine hydrochloride. Specifications

GOST 5789−78 Reagents. Toluene. Specifications

GOST 5848−73 Reagents. Formic acid. Specifications

GOST 5955−75 Reagents. Benzene. Specifications

GOST 6552−80 Reagents. Orthophosphoric acid. Specifications

GOST 6691−77 Reagents. Urea. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 9816.0−84 Tellurium technical. General requirements for methods of analysis

GOST 10163−76 Reagents. Starch soluble. Specifications

GOST 10298−79 Selenium technical. Specifications

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

GOST 12026−76 laboratory filter Paper. Specifications

GOST 24104−2001* laboratory Scales. General technical requirements
_______________
* On the territory of the Russian Federation GOST R 53228−2008 «Scales non-automatic actions. Part 1. Metrological and technical requirements. Test».


GOST 25336−82 Glassware and equipment laboratory glass. The types, basic parameters and dimensions

GOST 27068−86 Reagents. Chernovetskiy sodium (sodium thiosulfate) 5-water. Specifications

GOST 29169−91 (ISO 648−77) oils. Pipette with one mark

GOST 29227−91 (ISO 835−1-81) oils. Pipettes are graduated. Part 1. General requirements

GOST 29251−91 (ISO 385−1-84) oils. Burette. Part 1. General requirements

GOST ISO 5725−6-2003** Accuracy (trueness and precision) of methods and measurement results. Part 6. The use of precision values in practice
_______________
** On the territory of the Russian Federation GOST R ISO 5725−6-2002 «Accuracy (trueness and precision) of methods and measurement results. Part 6. The use of precision values in practice».


Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or published annually by the information sign «National standards» published as on January 1 of the current year and related information published monthly indexes published in the current year. If the reference standard is replaced (changed), when using this standard should be guided by replacing (amended) standard. If the reference standard is cancelled without replacement, then the situation in which the given link applies to the extent that does not affect this link.

(Added, Rev. N 3).

1B. CHARACTERISTICS OF INDICATORS OF MEASUREMENT ACCURACY

A measure of the accuracy of measuring the mass fraction of selenium corresponds to the characteristics given in table 1 (if of 0.95).

Limit values of repeatability and reproducibility of measurements for a confidence probability of 0.95 is given in table 1.

Table 1 — values of the indicator of measurement accuracy, limits of repeatability and reproducibility of measurement with confidence probability of 0.95

Percentage

(Added, Rev. N 3).

2. EXTRACTION-PHOTOMETRIC METHOD

2.1. The essence of the method

The method is based on the interaction of ortopeediline with selentine in a weakly acid medium at a pH of 0−2,5. The complex is extracted with benzene or toluene. The maximum absorption of coloured compounds is observed at a wavelength of 315 nm. For the iron binding should be added phosphoric acid, bismuth — Trilon B. If a does not contain tellurium, bismuth and Trilon B is not added.

(Changed edition, Rev. N 1, 3).

2.2. Measurement means, auxiliary devices, materials, solutions

When performing measurements using the following measuring instruments and auxiliary devices:

— spectrophotometer or the photoelectric photometer with all accessories necessary for measurements at a wavelength of 315 nm;

— the stove is electric with a closed heating element for temperature up to 400 °C;

— special laboratory scales of accuracy class according to GOST 24104;

— bath water;

— volumetric flasks 2−50−2, 2−100−2, 2−200−2, 2−500−2 according GOST 1770;

— flasks KN-1−100−24/29 TCS GOST 25336;

— glasses-1−50 TCS In-1−100 TCS-1−200 TCS according to GOST 25336;

— separating funnel VD-1−100 TC GOST 25336;

tube П2Т-60−250 TC GOST 25336;

— hour glass.

When taking measurements, use the following products and solutions:

— distilled water according to GOST 6709;

— nitric acid according to GOST 4461;

— formic acid according to GOST 5848;

— hydrochloric acid according to GOST 3118;

— phosphoric acid according to GOST 6552;

— ammonia water according to GOST 3760;

— citric acid according to GOST 3652, solution mass concentration of 400 g/DM, freshly prepared;

— salt is the disodium Ethylenediamine-N, N, N', N' — tetraoxane acid 2-water (Trilon B) according to GOST 10652, a solution of molar concentration 0.1 mol/DM;

— benzene according to GOST 5955;

— toluene according to GOST 5789, distilled;

— selenium GOST 10298 or other normative documents;

— Orto-phenylendiamine indicator [1], the solution of the mass concentration of 10 g/DM, freshly prepared;

the filter paper according to GOST 12026;

filters obestochennye [2] or similar;

paper universal indicator [3].

(Changed edition, Rev. N 1, 2, 3).

2.2. Preparations for the measurements

2.2.1. For construction of calibration curve prepare solutions of known concentration of selenium.

In preparing the solution And the mass concentration of selenium of 0.1 mg/cma portion of selenium with a mass of 0.0500 g, is placed in a beaker with a capacity of 100 (200) cm, flow 10 cmof hydrochloric acid 5−7 drops of nitric acid and heated in a water bath until complete dissolution of selenium. Then pour 20 cmof water and place the resulting solution in a volumetric flask with a capacity of 500 cm, add 15 cmof hydrochloric acid, made up to the mark with water and mix.

In the preparation of a solution of mass concentration of selenium 0.01 mg/cm10.0 cmsolution And placed in a volumetric flask with a capacity of 100 cm, add 2 cmof hydrochloric acid, made up to the mark with water and mix.

2.2.2. Construction of calibration curve

Six beakers (flasks) with a capacity of 100 cmeach placed 1,0; 2,0; 3,0; 4,0 and 7,0 cmof solution B and 1.5 cmof solution A, which corresponds to 0,01; 0,02; 0,03; 0,04; 0,07 and 0,15 mg of selenium, and continue as described in 2.3.1. According to the obtained results build a calibration curve.

A solution of comparison used benzene or toluene.

2.2 a (Introduced later, Rev. N 3).

2.3. Analysis

2.3.1. A sample of tellurium weighing 0.5 g were placed in a glass with a capacity of 100−200 cm, 10−15 cm pouredhydrochloric acid, 2−3 cmof nitric acid, cover the beaker with a cover glass and gently heated to remove oxides of nitrogen.

Glass glass is removed, wash it with water over the glass, place the resulting solution in a volumetric flask with a capacity of 50−200 cm(depending on the mass fraction of selenium), dilute to the mark with water and mix. If the mass fraction of selenium 0,001−0,005%, then you should use the entire solution.

Select aliquot part of the solution 5−10 cmand placed it in a glass (flask) with a capacity of 100−150 cm. To aliquote part pour 10 cmof freshly prepared citric acid solution, dilute with water to volume of 30−35 cm, add 1 cmof formic acid, 5cmphosphoric acid and 0.5−1.0 cmof solution Trilon B and mix. Set the pH value of 1−1,5 on the universal indicator paper by adding ammonia. Then add 3 cmof a solution of ortopeediline and leave for 15−20 min.

The resulting solution was placed in a separating funnel with a capacity of 100−150 cm, pour 5 cmof benzene or toluene and extracted for (2±0,1) min. Extract decanted into a dry test tube and measure the optical density on the spectrophotometer at a wavelength of 315 nm in a cuvette with a layer thickness of 10 mm Solution comparison is benzene or toluene.

Solution comparison is benzene. The mass of selenium is determined according to the calibration schedule.

(Changed edition, Rev. N 1, 2).

2.3.2. (Deleted, Rev. N 3).

2.4. Processing of the results

2.4.1. Mass fraction of selenium (X) in percent is calculated by the formula

,

where is the mass of selenium was found in the calibration graphics mg;

 — the volume of solution in a volumetric flask, cm;

 — volume aliquote part of the solution, cm;

m — weight of tellurium, g;

 — weight of selenium in solution in the reference experiment, was found in the calibration graphics mg;

 — a conversion factor of milligrams to grams.

(Changed edition, Rev. N 3).

2.4.2. (Changed edition, Rev. N 2); (Deleted, Rev. N 3).

3. TITRIMETRIC METHOD

3.1. The essence of the method

The method is based on the reaction between Selenite and thiosulfate with the formation of celeberations and tetrathionate in the presence of excess thiosulfate. Determination of selenium — iodometric titration.

3.2. Measurement means, auxiliary devices, materials, solutions

When performing measurements using the following measuring instruments and auxiliary devices:

— the stove is electric with a closed heating element for temperature up to 350 °C;

— special laboratory scales of accuracy class according to GOST 24104;

— bath water;

— flasks KN-2−250−29/32 according to GOST 25336;

— glasses-1−400 TCS In-1−600 TCS according to GOST 25336;

— burette I-1−2-25−0,1; I-2−25−0,1; I-2−50−0,1 according to GOST 29251;

— funnel filtering laboratory according to GOST 25336;

— hour glass.

When taking measurements, use the following products and solutions:

— distilled water according to GOST 6709;

— nitric acid according to GOST 4461;

— sulfuric acid according to GOST 4204, diluted 1:1;

— hydrochloric acid according to GOST 3118 diluted 1:9;

— sodium hydroxide (sodium hydroxide) according to GOST 4328, solution mass concentration of 200 g/DM;

— potassium iodide according to GOST 4232, solution mass concentration of 50 g/DM;

— soluble starch according to GOST 10163, solution mass concentration of 5 g/DM;

— urea according to GOST 6691;

— Chernovetskiy sodium (sodium thiosulfate) according to GOST 27068, solution of molar concentration 0.05 mol/DM;

— hydroxylamine hydrochloride according to GOST 5456;

— phenolphthalein indicator [4], a solution of 1 g/DM;

— selenium at 10298 or other normative documents;

filters obestochennye [2] or similar;

the filter paper according to GOST 12026 marks f, FS.

(Changed edition, Rev. N 2, 3).

3.2. Preparations for the measurements

3.2.1. In the preparation of a solution of soluble starch mass concentration of 5 g/DMof the starch sample weight of 0.5 g is stirred in 10 cmof water to obtain a homogeneous slurry, the mixture is slowly poured, with stirring, at 90 cmof boiling water and boil for 2 to 3 minutes, cool. The solution used freshly.

3.2.2. In preparing the solution servational sodium (sodium thiosulfate) molar concentration of 0.05 mol/DMweighed salt weight 12.5 g dissolved in 200 cmof boiled water. The solution was filtered into a measuring flask with volume capacity of 1000 cm, made up to the mark boiled and cooled water, and stirred. The solution is kept before use for 5−7 days.

3.2.3. The establishment of the mass concentration of the sodium thiosulfate

The mass concentration of sodium thiosulfate set as follows: a portion of selenium with a mass of 0.1 g was placed in a conical flask with a capacity of 250 cm, flow 10 to 12 cmof hydrochloric acid of 1 cmof nitric acid, cover the flask with a watch glass (cover) and heated to dissolve sample. Remove the glass, wash it over with the flask of water poured from 80 to 100 cmof hot water, add 4−4,5 g of urea and stirred.

After 15−20 min the solution was cooled and neutralized to phenolphthalein with sodium hydroxide solution until alkaline reaction. To a solution flow of 20 to 25 cmof sulphuric acid diluted 1:1 and cooled. Then the resulting solution is titrated with sodium thiosulfate in the amount of from 21 to 23 cm(add it under stirring, slowly in small portions). Then poured to the solution of 2−3 cmof potassium iodide solution with a mass concentration of 50 g/DM, 2−3 cm ofstarch solution and continue titration to the disappearance of the blue color of the solution.

The mass concentration of sodium thiosulfate expressed in grams of selenium per 1 cmof the solution in g/cm, is calculated by the formula

,

where is the mass of sample selenium, g;

 — the volume of sodium thiosulfate consumed for the titration, given the reference experiment, cm.

3.2.and (optionally Entered, Rev. N 3).

3.3. Analysis

A portion of the tellurium content of 1 g was placed in a conical flask with a capacity of 250−300 cm, add 20 cmof hydrochloric acid and 2 cmof nitric acid, cover with a cover glass and slightly heated to dissolve the sample, then remove the glass, wash it over with the flask and carefully evaporate the solution on a warm place plate to obtain a wet residue (preferably a water bath).

Then pour the 20−25 cmof hydrochloric acid and 60−80 cmof water, add a little filtrowanie mass, 2−2. 5 g of hydroxylamine and stirred. Leave for 2−3 hours in a warm place plate to the coagulation of the precipitate.

The precipitate was filtered off through a filter medium density, the cone which is enclosed a little filtrowanie mass, washed 2−3 times with hot hydrochloric acid (1:9), and then 6−8 times with hot water.

Selenium precipitate with the filter is transferred to a flask in which the precipitation was carried out, add 15−20 cmof hydrochloric acid and 1 cmof nitric acid and heated in a water bath to dissolve the residue. To the obtained solution poured 80−100 cmof hot water, add 4−4,5 g of urea and continue as described in section 3.2 when establishing the mass concentration of the sodium thiosulfate.

3.4. Processing of the results

3.4.1. Mass fraction of selenium () in percent is calculated by the formula

,

where V — volume of sodium thiosulfate consumed in the titration, cm;

 — mass concentration of sodium thiosulfate, g/cmselenium;

m — weight of tellurium,

(Changed edition, Rev. N 3).

3.4.2. (Changed edition, Rev. N 2); (Deleted, Rev. N 3).

3.4.3. (Deleted, Rev. N 3).

4. The measurement results take the arithmetic mean of two parallel definitions, provided that the absolute difference between them in terms of repeatability does not exceed the values (with confidence probability of 0.95) limit of repeatability in table 1.

If the discrepancy between the results of parallel measurements exceeds the limit value of the frequency of occurrence, perform the procedure described in GOST ISO 5725−6 (paragraph 5.2.2.1).

(Added, Rev. N 3).

5. The absolute value allowable discrepancies between the two measurement results obtained in different laboratories, should not exceed the limit of reproducibility given in table 1 at a confidence level of 0.95. At default of this condition can be used the procedure set out in GOST ISO 5725−6.

(Added, Rev. N 3).

6. The differences in the assessment of mass fraction of selenium used for extraction-photometric method.

(Added, Rev. N 3).

Bibliography

Bibliography (added, Rev. N 3).