GOST 12697.11-77

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  ГОСТ 12697.11-77

GOST 12697.11−77 Aluminum. Method for determination of lead (with Amendments No. 1, 2)

GOST 12697.11−77

Group B59

INTERSTATE STANDARD

ALUMINIUM

Method for determination of lead

Aluminium. Method for determination of lead

ISS 77.120.10
AXTU 1709

Date of introduction 1979−01−01

The decision of the State standards Committee of the Council of Ministers of the USSR from 27.09.77 N 2315 date of introduction is established 01.01.79

Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

EDITION with Amendments No. 1, 2 approved in November 1985, may 1988 (IUS 2−86, 8−88).


This standard sets the polarographic method for the determination of lead in aluminum (with a mass fraction of lead from 0.001 to 0.1%). The method is based on polarography of lead in the solution prepared accordingly, in the voltage interval from minus 0.35 to minus 0,8 Century

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 12697.1−77 and GOST 25086−87.

(Changed edition, Rev. N 1, 2).

2. APPARATUS, REAGENTS AND SOLUTIONS

Polarograph AC type PU-1 or similar type.

Laboratory scales according to GOST 24104−88* 2nd accuracy class with the weighing error of 0.0002 g.
________________
* From 1 July 2002 was put into effect GOST 24104−2001**.

** On the territory of the Russian Federation GOST R 53228−2008. — Note the manufacturer’s database.

The gaseous nitrogen according to GOST 9293−74.

Aluminum brand A995 according to GOST 11069−2001.

Solution of aluminum 28 g/DM; prepared as follows: 14 g of aluminum is placed in a beaker with a capacity of 800 cm, dissolved in 300 cmof hydrochloric acid diluted 1:1 and added to accelerate the dissolution one or two drops of metallic mercury.

The solution was transferred to volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

Bromine according to GOST 4109−79.

Hydroxylamine hydrochloric acid according to GOST 5456−79, a freshly prepared solution with a mass fraction of 10%.

Nitric acid GOST 4461−77, diluted 3:2.

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

Mercury GOST 4658−73.

Lead according to GOST 3778−98.

Solutions of lead standard.

Solution A, prepared as follows: 0,1400 g of lead dissolved in 10 cmof nitric acid, diluted 3:2, add 10 cmof hydrochloric acid and evaporated to dryness. Repeat the evaporation with 10 cmof hydrochloric acid to the wet residue of salts. The residue is dissolved in water, the solution was transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof solution A contains 0.14 mg lead (Pb).

Solution B is prepared before use as follows: pipette take 50 cmof solution A in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

1 cmof solution B contains 0.14 mg lead (Pb).

Sec. 2. (Changed edition, Rev. N 2).

3. ANALYSIS

3.1. Weighed aluminium weighing 0.7 g was placed in a beaker with a capacity of 150 cmand dissolved in 20 cmof hydrochloric acid diluted 1:1. Beaker cover watch glass, and heated to dissolve sample. Once dissolved, add 2−3 drops of bromine and evaporated the solution until a wet residue of salts.

The solution was then cooled, washed glass and walls of glass with water and evaporated again to obtain a wet residue of salts. The residue is dissolved in 10−15 cmof hot water, add 2cmof a solution of hydroxylamine hydrochloric acid and boil for 1−2 min. then solution was cooled, transferred to a volumetric flask with a capacity of 25 cm, is diluted to the mark with water and mix. Part of the solution is taken into the cell and Donna mercury, pass nitrogen for 5 min and polarographic lead in the voltage interval from minus 0.35 to minus 0.8, with appropriate sensitivity of the instrument.

Copper and zinc are determined from the same solution, polarography copper in the voltage interval from minus 0.05 to minus 0.4 V, and zinc — from minus 0.8 to minus 1.2 V.

At the same time spend control experience.

Mass of lead is determined according to the calibration schedule, taking into account the amendment in the reference experiment.

3.2. Construction of calibration curve (when the mass fraction of lead from 0.001 to 0.01%)

In a glass with a capacity of 150 cmis placed 25 cmof a solution of aluminium in 28 g/DMand of microburette add 0; 0,5; 1,0; 2,0; 3,0 and 5,0 cmof solution B, which corresponds to 0; 0,007; 0,014; 0,028; and 0,042 0,070 mg of lead; in each glass add 2−3 drops of bromine and evaporated to obtain a wet residue of salts. The side of the Cup washed with water and again evaporated to moist residue of salts. The residue is dissolved in 10−15 cmof hot water, pour 2 cmof a solution of hydroxylamine hydrochloric acid and boil for 1−2 minutes Further analysis performed as described in section 3.1.

According to the data obtained polarographically solutions, and the known masses of lead build the calibration graph. When you replace the capillaries, you need to build a new schedule.

3.3. Construction of calibration curve (when the mass fraction of lead from 0,01 to 0,1%)

In a glass with a capacity of 150 cmis placed 25 cmof a solution of aluminium in 28 g/DMand add from microburette 0; 0,5; 1,0; 2,0; 3,0 and 5,0 cmof solution A, which corresponds to 0; 0,07; 0,14; 0,28; 0,42 and 0.70 mg of lead. Then do as indicated in the claims.3.1, 3.2.

(Changed edition, Rev. N 2).

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of lead (a) percentage calculated by the formula

,

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

the weight of aluminium,

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

(Changed edition, Rev. N 2).