GOST 11739.18-90

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  ГОСТ 11739.18-90

GOST 11739.18−90 Alloys aluminium cast and wrought. Method for determination of lead

GOST 11739.18−90

Group B59

STATE STANDARD OF THE USSR

ALLOYS ALUMINIUM CAST AND WROUGHT

Method for determination of lead

Aluminium casting and wrought alloys.
Method for determination of plumbum

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; O. L. Sikorska, PhD. 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 1962

3. The frequency of inspection — 5 years

4. Standard corresponds to ISO 4192 in part wrought aluminium alloys, essence method dissolve the sample, measurement of atomic absorption and processing of the results

5. REPLACE GOST 11739.18−78

6. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard establishes the atomic absorption method for the determination of lead (with a mass fraction of lead from 0.01 to 1.5%).

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 samples in hydrochloric acid in the presence of nitric acid and subsequent atomic absorption measurement of lead at a wavelength of 217,0 or is 283.3 nm in flame acetylene-air.

3. APPARATUS, REAGENTS AND SOLUTIONS

Spectrophotometer of atomic absorption with a radiation source for lead.

Acetylene according to GOST 5457.

Hydrochloric acid according to GOST 3118, density of 1.19 g/cm, mortar 1:1 and 1:99.

Nitric acid according to GOST 4461, density 1,35−1,40 g/cmand a solution of 1:1.

Hydrofluoric acid according to GOST 10484.

A mixture of hydrochloric and nitric acids: 500 cmof water is carefully added with stirring 375 cmof hydrochloric acid and 125 CCof nitric acid.

Nickel chloride according to GOST 4038, a solution of 1 g/DM.

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

A solution of aluminum 20 g/DM: 10 g of aluminum is placed in a beaker with capacity of 500 cm, add 50 cmof water and small portions 200 cmmixture of hydrochloric and nitric acids and dissolve with a moderate heat, adding 1 cmof solution of chloride Nickel. The solution was heated to remove brown fumes and reduce the volume to 100 cm, then cooled to room temperature, transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

Lead brand S000 GOST 22861*.
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* On the territory of the Russian Federation GOST 22861−93. — Note the manufacturer’s database.

Standard solutions of lead.

Solution a: 0.5 g of lead was placed in a conical flask with a capacity of 250 cmadd 30 cmof a solution of nitric acid. After dissolution, the sample solution is boiled for 2 min to remove oxides of nitrogen. 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.

1 cmof the solution contains 0.001 g of lead.

Solution B: 10 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 0.0001 g of lead.

4. ANALYSIS

4.1. A portion of sample weighing 0.5 g (at a mass fraction of lead from 0.01 to 0.25%) or 0.2 g (for a mass fraction of lead from 0.25 to 1.5%) is placed in a conical flask with a capacity of 250 cm, pour approximately 10 cmof water, then small portions of 20 cmof a mixture of hydrochloric and nitric acids. The beaker cover watch glass and heated until complete dissolution of the sample, the solution was evaporated to a volume of about 10 cmand cooled to room temperature. To the residue add 25 cmof water and boil the solution for 2 min.

Watch glass and walls of the flask rinsed with water. The solution was cooled to room temperature, transferred to a volumetric flask with a capacity of 100 cm, add 5 cmof a solution of nitric acid, made up to the mark with water and mix

.

4.2. When the mass fraction of silicon is less than 1% solution, if it is not transparent, was filtered through a dry filter medium density (white ribbon) in a beaker, discarding the first portions of the filtrate.

4.3. 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 precipitate on the filter is washed 1−2 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, add 5 cmhydrofluoric acid and nitric acid drop by drop until a clear solution. Next, the solution was evaporated to dryness, after cooling, the residue moistened with 2−3 cmof water and dissolve in 2−3 cmof nitric acid when heated.

The solution is attached to the main filtrate in a volumetric flask with a capacity of 100 cm, add 5 cmof a solution of nitric acid, made up to the mark with water and mix

.

4.4. The solution in the reference experiment is prepared according to PP.4.1, 4.2 or 4.3, using is sample the sample the sample of aluminium.

4.5. Construction of calibration graphs

4.5.1. When the mass fraction of lead from 0,01 to 0,1% in seven volumetric flasks with a capacity of 100 cmpoured in 25 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 lead.

4.5.2. When the mass fraction of lead than 0.1 to 0.25 per cent in six volumetric flasks with a capacity of 100 cmpoured in 25 cmof a solution of aluminium, in five of them measure 0,5; 0,75; 1,0; 1,25; 1,5 cmstandard solution A, which corresponds to 0,0005; 0,00075; 0,001; 0,00125; 0.0015 g of lead.

4.5.3. For the mass concentration of lead in excess of 0.25 to 1.5% in seven volumetric flasks with a capacity of 100 cmpour 10 cmof a solution of aluminum in six of them measure 0,5; 1,0; 1,5; 2,0; 2,5; 3,0 cmof solution A, which corresponds to 0,0005; 0,001; 0,0015; 0,002; 0,0025; 0,003 g lead.

4.5.4. The solutions in flasks in PP.4.5.1, 4.5.2 and 4.5.3 added 5 cmof a solution of nitric acid, made up to the mark with water and mix.

4.6. The sample solution, solution control experience and solutions to build the calibration curve is sprayed into the flame of acetylene-air and measure the atomic absorption of lead at a wavelength of 217,0 or is 283.3 nm.

According to the obtained values of atomic absorption and corresponding mass concentrations of lead build the calibration graph.

Mass concentration of lead 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 lead (a) percentage calculated by the formula

,

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

 — mass concentration of lead 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.