GOST 11739.8-90

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  ГОСТ 11739.8-90

GOST 11739.8−90 Alloys aluminium cast and wrought. Methods for determination of potassium

GOST 11739.8−90

Group B59

STATE STANDARD СОЮ3А SSR

ALLOYS ALUMINIUM CAST AND WROUGHT

Method of determining potassium

Aluminium casting and wrought alloys.
Method for determination of potassium

AXTU 1709

Valid from 01.07.91
before 01.07.96*
________________________________
* Expiration removed
Protocol 5−94 N Interstate Council
for standardization, Metrology and certification
(IUS N 11/12, 1994). — Note the manufacturer’s database.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of aviation industry of the USSR

DEVELOPERS

V. G. Davydov, doctor of engineering. Sciences; V. A. Moshkin, PhD. tech. Sciences; G. I. Friedman, PhD. tech. Sciences; M. N. Gorlova, PhD. chem. Sciences; V. A. Osipova, Cand. chem. Sciences

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 28.06.90 N 1961

3. The frequency of inspection — 5 years

4. REPLACE GOST 11739.8−78

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard sets flame photometric method for the determination of potassium at a mass proportion of from 0.001 to 0.05%.

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 25086 with the Supplement.

1.1.1. For the results analysis be the arithmetic mean of results of two parallel measurements.

2. THE ESSENCE OF THE METHOD

The method is based on dissolving the sample in hydrochloric acid and subsequent measurement of the radiation intensity of potassium at a wavelength 766,5 nm in the flame acetylene-air.

3. APPARATUS, REAGENTS AND SOLUTIONS

The fiery photometer or spectrophotometer atomic absorption operating in the mode of emission.

Drying oven with thermostat.

Quartz apparatus for distillation.

Quartz flasks.

Water, double-distilled in quartz apparatus (redistilled for the preparation of solutions and analysis); stored in a plastic container.

Acetylene according to GOST 5457, cleaned with sulfuric acid.

Sulfuric acid according to GOST 4204, density 1.84 g/cm.

Hydrochloric acid according to GOST 14261 or GOST 3118, distilled in a quartz apparatus, a density of 1.19 g/cm, mortar 1:1 and 1:99.

Hydrofluoric acid according to GOST 10484.

Hydrogen peroxide according to GOST 10929.

Nickel chloride according to GOST 4038, a solution of 2 g/DM.

Aluminium GOST 11069* brand А999.
_______________
* On the territory of the Russian Federation GOST 11069−2001. — Note the manufacturer’s database.

A solution of aluminum 50 g/DM: 25 g of aluminum was placed in a quartz flask with a capacity of 600 cm, add 50 cmof water and then small portions of 400 cmof a hydrochloric acid solution (1:1), dissolved by heating, adding 1 cmof solution of chloride Nickel. The solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix. The solution was stored in a plastic container.

Potassium chloride according to GOST 4234.

Standard solutions of potassium

Solution a: 1,782 g of potassium chloride, previously dried at a temperature of 105−110°C, is dissolved in 50 cmof water, transfer the solution into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of potassium.

Solution B: 10 cmstandard solution And transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmof a solution contains 0.0001 g of potassium.

Solution: 10 cmstandard solution B is transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

1 cmof the solution contains 0,00001 g of potassium.

Solutions B and C were prepared immediately before use.

4. ANALYSIS

4.1. A portion of the sample weighing 1 g is placed in a quartz conical flask with a capacity of 250 cm, equipped with reverse refrigerator, quartz, add portions 20 cmof a hydrochloric acid solution of 1:1 and heated moderately until the end of the dissolution. Add 3−5 drops of hydrogen peroxide and boiled for 3 min. the Solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

4.2. When the mass fraction of silicon in excess of 1% after completion of dissolution according to claim 4.1 solution is filtered through a filter medium density (white ribbon) in a volumetric flask with a capacity of 100 cm.

The filter cake was washed 3−4 times with hot hydrochloric acid (1:99) in portions of 10 cm(primary filtrate).

The filter with precipitate was placed in a platinum crucible, dried, incinerated, preventing ignition, and calcined at 500−600 °C for 3 min. After cooling the content of crucible add four drops of sulphuric acid, 5 cmhydrofluoric acid and nitric acid drop by drop until a clear solution. The solution was then evaporated to dryness, after cooling, the residue moistened with 2−3 cmof water and dissolve in 2−3 cmof hydrochloric acid (1:1) under heating.

The solution is attached to the main filtrate in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

4.3. The solution in the reference experiment is prepared according to PP.4.1 and 4.2 in at least two parallel with all the reagents used in the analysis.

4.4. Construction of calibration graphs

4.4.1. When the mass fraction of potassium from 0.001 to 0.005% in seven volumetric flasks with a capacity of 100 cmplaced at 20 cmof a solution of aluminium, in five of them measure 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution, which corresponds to the 0.00001; 0,00002; 0,00003; 0,00004; 0,00005 g of potassium.

4.4.2. When the mass fraction of potassium more than 0.005 to 0.05% in eight volumetric flasks with a capacity of 100 cmplaced at 20 cmof a solution of aluminum in six of them measure 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to 0,00005; 0,0001; 0,0002; 0,0003; 0,0004; 0,0005 g of potassium.

4.4.3. The solutions in flasks in PP.4.4.1 and 4.4.2 topped up to the mark with water and mix.

Solutions not containing potassium, are the solutions in the reference experiment when constructing the calibration graphs.

4.5. The sample solution, the solutions in the reference experiment and the solutions for constructing the calibration graphs is sprayed into the flame of acetylene-air and measure the emission intensity of potassium at a wavelength 766,5 nm.

According to the obtained values of radiation intensity and corresponding mass concentrations of potassium build the calibration graph.

Mass concentration of potassium in the sample solution and the solution of control and experience determined by the calibration schedule.

5. PROCESSING OF THE RESULTS

5.1. Mass fraction of potassium () in percent is calculated by the formula

,

where is the mass concentration of potassium in the sample solution found by the calibration schedule, g/cm;

 — mass concentration of potassium in solution in the reference experiment, was found in the calibration schedule, g/cm;

 — the volume of the sample solution, cm;

 — weight of sample, g

.

5.2. Discrepancies in the results must not exceed the values given in the table.