GOST 12697.14-90

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  ГОСТ 12697.14-90

GOST 12697.14−90 Aluminium. Method of determination of calcium

GOST 12697.14−90

Group B59

INTERSTATE STANDARD

ALUMINIUM

Method of determination of calcium

Aluminium. Method for the determination of calcium

ISS 77.120.10
AXTU 1709

Date of introduction 1991−07−01

INFORMATION DATA

1. INTRODUCED by the Ministry of metallurgy of the USSR

DEVELOPERS

N.Ponomareva, I. M. Kozlovskaya, T. I. Zhilina

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 10.12.90 N 3086

3. The standard fully complies ST SEV 6738−89

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. REISSUE


This standard establishes the atomic absorption method for the determination of calcium in aluminum at a mass proportion of calcium from 0.005 to 0.2%.

The method is based on dissolving the sample in hydrochloric acid and measuring the nuclear absorption of calcium at a wavelength 422,7 nm in a flame acetylene — nitrous oxide.

1. GENERAL REQUIREMENTS

General requirements for method of analysis according to GOST 12697.1.

2. APPARATUS, REAGENTS AND SOLUTIONS

Spectrophotometer atomic absorption model of Perkin-Elmer, Saturn or similar type with a radiation source for calcium and burner for flame acetylene — nitrous oxide.

Water, double-distilled.

Acetylene in cylinders for technical GOST 5457.

The nitrous oxide.

Hydrochloric acid according to GOST 14261, diluted 1:1.

Nickel (II) chloride according to GOST 4038, a solution with a mass fraction of 0.2%.

Mercury GOST 4658.

Hydrogen peroxide according to GOST 10929, a solution with a mass fraction of 3%.

Acetone according to GOST 2603.

Aluminum brand А999 according to GOST 11069, shavings. Immediately before use, the chips are cleaned in a small amount of hydrochloric acid solution, washed with water, acetone, dried in a drying Cabinet at 100 °C for 2−3 min and cooled in a desiccator.

Solution of aluminum 10 g/l: 5.0 g of aluminium is dissolved in 200 cmof a hydrochloric acid solution in a beaker with a capacity of 400 cmwhen heated. To accelerate the dissolution, you can add 1 cmof a solution of Nickel chloride or a drop of mercury. The solution was cooled, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix. Solution store in a plastic container.

Potassium chloride according to GOST 4234, solution with a mass fraction of 1%.

Calcium carbonate according to GOST 4530.

Standard solutions of calcium.

Solution a: 2,4973 g of calcium carbonate, previously dried at 100 °C to constant weight and cooled in a desiccator, dissolved in 20 cmof a hydrochloric acid solution under heating. The solution is transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix. Solution store in a plastic container.

1 cmof solution A contains 1.0 mg of calcium.

Solution B: 10.0 cmsolution And transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. The solution is prepared before use.

1 cmof a solution contains 0.1 mg of calcium.

Solution: 10,0 cmof solution B is transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. The solution is prepared before use.

1 cmof the solution contains 0.01 mg of calcium.

3. ANALYSIS

3.1. Weighed aluminium weighing 0.5 g were placed in a glass with a capacity of 250 cm, flow 20 cmof a hydrochloric acid solution. After the cessation of violent reaction solution is heated and added some drops of hydrogen peroxide.

After dissolution, the sample solution was boiled to remove excess hydrogen peroxide, cooled and transferred to a volumetric flask with a capacity of 100 cm, add 10 cmof potassium chloride solution, made up to the mark with water and mix.

For the mass concentration of calcium less than 0.1% for the measurement of atomic absorption using a full sample solution.

For the mass concentration of calcium of more than 0.1% aliquot part of the sample volume of 50.0 cmis placed in a volumetric flask with a capacity of 100 cm, add 5 cmof potassium chloride solution, made up to the mark with water and mix.

The solution in the reference experiment is prepared using, instead of sample of sample weighed aluminum brand А999.

Measure the atomic absorption of calcium in the sample solution, the solution control experience and solutions to build the calibration curve at the wavelength 422,7 nm in a flame acetylene — nitrous oxide.

From the value of atomic absorption of the sample solution and subtract the value of atomic absorption solution in the reference experiment. Ground calcium find calibration schedule

.

3.2. Construction of calibration curve

In seven of the eight volumetric flasks with a capacity of 100 cmis placed 2,0; 5,0 and 10,0 cmstandard solution and 2,0; 3,0; 4,0 and 5,0 cmstandard solution B, which corresponds to 0,02; 0,05; 0,1; 0,2; 0,3; 0,4 and 0.5 mg of calcium.

For the mass concentration of calcium less than 0.1% in all flasks add 50 cmof a solution of aluminum and 10 cmof potassium chloride solution with mass share of calcium more than 0.1% by 25 cmof a solution of aluminum and 5 cmof potassium chloride solution, then the solution was topped to the mark with water and mix.

The atomic absorption of calcium in solution is measured in accordance with paragraph 3.1.

From the values of atomic absorption solutions subtract the value of atomic absorption of a solution containing a standard solution of calcium, and according to the obtained values and corresponding masses of calcium build the calibration graph.

4. PROCESSING OF THE RESULTS

4.1. 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, mg;

 — the volume of the sample solution, cm;

 — weight of sample, g;

 — volume aliquote part of the solution, cm.

4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in the table.