19014.3 GOST-73

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  ГОСТ 19014.3-73

GOST 19014.3−73 Silicon crystal. Methods for determination of calcium (with Amendments No. 1, 2, 3)

GOST 19014.3−73*

Group B59

STATE STANDARD OF THE USSR

SILICA, CRYSTALLINE

Methods for determination of calcium

Crystal silicon. Methods of calcium determination*

______________
* The name of the standard. Changed the wording, Rev. N 3.

AXTU 1709

Date of introduction 1975−01−01

The decision of the State Committee of standards of Ministerial Council of the USSR from July 23, 1973 N 1804 the introduction of set with 01.01.75

Proven in 1984 by the Resolution of Gosstandard dated August 15, 1984, 2874 N validity extended to 01.01.90**
________________
** 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 2178−54 in part of sec. V

* REISSUE (November 1985) with Amendments No. 1, 2 approved in July 1979, August 1984 (IUS 8−79, 11−84)

AMENDED N 3, approved and put into effect from 01.01.90 by the Resolution of Gosstandart of the USSR from 27.06.89 N 2091

Change No. 3 made by the manufacturer of the database in the text IUS N 11, 1989


This standard specifies the titrimetric and atomic absorption methods for the determination of calcium (when calcium mass fraction from 0.30 to 1.60%) in crystalline silicon.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 19014.0−73.

1A. TITRIMETRIC METHOD

The essence of the method based on the complexometric titration of calcium. Interfering components (iron, titanium, etc.) are masked with triethanolamine and tartaric acid or separated by geksametilentetramina.

Section 1A. (Added, Rev. N 1).

2. REAGENTS AND SOLUTIONS

Potassium hydroxide according to GOST 24363−80, a solution with a mass fraction of 20%.

Trilon B (III chelating agent, disodium salt of ethylenediaminetetraacetic acid) according to GOST 10652−73, solution with molar concentration of 0.05 mol/DM. The correction factor for the solution with molar concentration of 0.05 mol/DMTrilon find, as specified in sec. 2 GOST 19014.1−73.

Indigo Carmine solution with a mass fraction of 0,25% solution of ethyl alcohol with a mass fraction of 50%.

The technical rectified ethyl alcohol GOST 18300−87.

Thymolphthalein.

Fluoresce.

The indicator compound I; prepared as follows: 0.4 g of fluoresone, 0.33 g of thymolphthalein and 40 g of potassium chloride were mixed and ground in an agate mortar.

Murexide. Indicator mixture II; prepared as follows: 1.0 g of fluoresone, 0.4 g of murexide, 40 g of potassium chloride were mixed and ground in an agate mortar.

Potassium chloride according to GOST 4234−77.

Triethanolamine, diluted 1:9.

Tartaric acid according to GOST 5817−77, a solution with a mass fraction of 50%.

Standard solution of zinc nitrate solution with molar concentration of 0.05 mol/l; prepared as described in sect.2 GOST 19014.1−73.

Nitric acid GOST 4461−77.

Ammonia water according to GOST 3760−79.

Ammonium chloride according to GOST 3773−72.

Geksametilentetramin (methenamine) technical GOST 1381−73, solution with mass fractions of 25 and 0.5%.

(Changed edition, Rev. N 2, 3).

3. ANALYSIS

For the analysis, use the solution prepared as described in section 3.1 GOST 19014.1−73.

Of volumetric flasks with a capacity of 250 cmtaken 100 cmof solution in the conical flask with a capacity of 500 cm, add 10 cmof a solution of triethanolamine, 10 cmof a solution of tartaric acid. Next add 3−5 drops of Indigo Carmine solution and a solution of potassium hydroxide until the color changes from blue to yellow, and then add an excess of potassium hydroxide 3−4 cm.

To the resulting solution was added 0.1−0.2 g of a mixture of I or II indicators and titrated with a solution of Trilon B before transition of colouring from green to purple with simultaneous quenching of fluorescence.

At the same time through all stages of the analysis carried out control experience for contamination of reagents.

The separation of the hydroxides of iron, titanium and aluminum may be performed as follows: the volumetric flask with a capacity of 250 cmtaken 100 cmof solution in a glass with a capacity of 400 cm. Then pour 5−6 drops of nitric acid and heated to boiling. The solution is neutralized with ammonia before precipitation of hydroxides. The precipitate is dissolved with hydrochloric acid diluted 1:1, surging dropwise. To the solution was added 0.5 g of ammonium chloride, poured 10 cmof a solution of hexamine with a mass fraction of 25%, heated for 20 min to coagulate the precipitate and filter in a conical flask with a capacity of 500 cmthrough the filter «white ribbon». Precipitate was washed 5−6 times with a warm solution of hexamine with a mass fraction of 0.5%, washing with this solution the side of the Cup. To the filtrate add 3−4 drops of Indigo Carmine solution and further determination of calcium is carried out as specified in clause 3.1.

(Changed edition, Rev. N 3).

4. PROCESSING OF THE RESULTS

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* The name of the section. Changed the wording, Rev. N 3.

4.1. Mass fraction of calcium () in percent is calculated by the formula

,

where  — volume of solution with molar concentration of 0.05 mol/DMTrilon B, used for titration of calcium, cm;

0,002004 — mass concentration of a solution with molar concentration of 0.05 mol/DMTrilon B, expressed in grams of calcium;

 — the total volume of solution, cm;

 — volume aliquote part of the solution, cm;

 — correction factor;

 — the weight of the portion of the silicon,

4.2. Permissible discrepancies in the results of parallel definitions should not exceed the values given in the table.

The method used in the dispute in the assessment of the quality of the silicon crystal.

4.1, 4.2. (Changed edition, Rev. N 3).

5. ATOMIC ABSORPTION METHOD

The essence of the method consists in measuring the atomic absorption of calcium at a wavelength 422,7 nm in a flame nitrous oxide — acetylene.

Section 5. (Added, Rev. N 3).

6. APPARATUS, REAGENTS AND SOLUTIONS

Atomic absorption spectrometer with all accessories of the «Perkin-Elmer», «Saturn» or similar.

Lamp with hollow cathode for calcium.

Acetylene in cylinders for technical GOST 5457−75.

Nitrous oxide cylinders medical.

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

Calcium carbonate according to GOST 4530−76.

Sodium carbonate according to GOST 83−79.

Sodium tetraborate 10-water according to GOST 4199−76, dehydrated at 400 °C.

Mix for fusion: mix sodium carbonate and sodium tetraborate in a ratio of 6:1 (by weight).

Standard calcium solution: 1,2500 g of calcium carbonate, previously dried at 105 °C and cooled in a desiccator, placed in a beaker with a capacity of 400 cm, moisten with water, add 30 cmof hydrochloric acid diluted 1:1, and 80−100 cmof water. After dissolution, the sample solution is transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of calcium.

The solution-background: 160 g of a mixture for fusion were placed in a glass with a capacity of 1000 cm, moistened with water and gently, in small portions, pour the 700 cmof hydrochloric acid diluted 1:1. After dissolution the solution was transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

Section 6. (Added, Rev. N 3).

7. ANALYSIS

7.1. For the analysis, use the solution prepared as specified in clause 7.1 GOST 19014.1−73, and diluted it 10 times.

Measure the value of atomic absorption in solutions of the sample solution, the control experience and solutions to build the calibration curve at the wavelength 422,7 nm in a flame nitrous oxide — acetylene. Mass of calcium in the sample solution and in the solution of control and experience determined by the calibration schedule, which is built with every shot.

At the same time through all stages of the analysis spend control experience.

7.2. Construction of calibration curve

In six volumetric flasks with a capacity of 250 cmpour 50 cmof the solution-background. Then enter 0; 0,2; 0,5; 1,0; 2,0; 3,0 cmstandard solution, which corresponds to 0; 0,0002; 0,0005; 0,001; 0,002; 0,003 g of calcium.

The solutions were topped up to the mark with water, mix and measure the absorbance of solutions as specified in clause 7.1.

According to the obtained values of atomic absorption and corresponding masses of calcium build the calibration graph.

Section 7. (Added, Rev. N 3).

8. PROCESSING OF THE RESULTS

8.1. Mass fraction of calcium () in percent is calculated by the formula

,

where is the mass of calcium in the sample solution found by the calibration schedule g;

 — the mass of calcium in solution in the reference experiment, was found in the calibration schedule g;

10 — value that takes into account dilution of the solution;

 — the weight of the portion of the sample,

8.2. Permissible discrepancies in the results of parallel definitions should not exceed the values given in the table.

Section 8. (Added, Rev. N 3).