GOST 15483.5-78

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  ГОСТ 15483.5-78

GOST 15483.5−78 (ST SEV 4810−84) Tin. Methods for determination of lead (with Amendments No. 1, 2, 3)

GOST 15483.5−78
(ST CMEA 4810−84)

Group B59

INTERSTATE STANDARD

TIN

Methods for determination of lead

Tin. Methods for determination of lead

AXTU 1709

Date of introduction 1980−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

DEVELOPERS

B. C. Baev, T. P. Almanova, C. B. Meshkov, G. M. Vlasov, L. V. Mishchenko, L. D. Savilov, R. D. Kresnicka

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 13.12.78 N 3300

3. The standard fully complies ST SEV 4810−84

4. REPLACE GOST 15483.5−70

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

______________
* On the territory of the Russian Federation GOST 3778−98, here and hereafter. — Note the manufacturer’s database.

6. Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)

7. REVISED (April 1999) with Amendments No. 1, 2, 3, approved in August 1984, October 1985, June 1989 (IUS 12−84, 1−86, 10−89)


This standard specifies the polarographic and atomic absorption methods for the determination of lead (with a mass fraction of lead from 0.005 to 3.1%) in tin all brands except tin of high purity.

The standard fully complies ST SEV 4810.

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis and security requirements — according to GOST 15483.0.

(Changed edition, Rev. N 1).

2. POLAROGRAPHIC METHOD

2.1. The essence of the method

The method is based on dissolving the sample in a mixture of hydrochloric, bromatological acid and bromine, the Stripping of tin in the form of bromide and polarographic determination of lead in hydrochloric acid medium in the range of potentials from minus 0.25 to minus 0.5 V relative to a saturated calomel electrode.

2.2. Apparatus, reagents and solutions

Polarograph with all accessories.

Hydrochloric acid according to GOST 3118 and diluted 1:3.

Nitric acid according to GOST 4461 and diluted 1:4.

Bromatologia acid according to GOST 2062.

Bromine according to GOST 4109.

The mixture of acids to dissolve fresh: to 45 cmof hydrochloric acid poured 45 cmbromatological acid, 10 cmof bromine, and mix thoroughly.

Sodium chloride according to GOST 4233.

The iron powder according to GOST 9849.

Gelatin food according to GOST 11293, freshly prepared solution with a mass fraction of 1%.

Nitrogen or argon with oxygen content of not more than 0.0005%.

Lead at 3778 GOST and GOST 22861.

The solution of lead standard: a sample of lead weight 0,5000 g placed in a beaker with a capacity of 250 cmand dissolved by heating in 20 cmof nitric acid, diluted 1:4. The solution was evaporated to wet salts, pour 15 cmof hydrochloric acid and evaporated to dryness. Repeat the evaporation twice, using each time 5 cmof hydrochloric acid. To the dry residue add 2 g of sodium chloride and poured 100 cmof hydrochloric acid diluted 1:3. Heat to dissolve the salt, cooled, poured the solution into a measuring flask with a capacity of 500 cm, made up to the mark with hydrochloric acid diluted 1:3 and stirred.

1 cmof the solution contains 1·10lead.

(Changed edition, Rev. N 2, 3

).

2.3. Analysis

2.3.1. Depending on the mass fraction of lead in the sample tin weight in accordance with table.1 is placed in a beaker with a capacity of 100 cmand dissolved in 15 cmof the mixture to dissolve initially at room temperature and then under low heat. The resulting solution was evaporated to dryness. To the dry residue add 10 cmof the mixture to dissolve and evaporated to dryness. This operation is repeated 5−6 times, each time using 5 cmof the mixture for dissolution. Pour 5 cmof nitric acid and evaporated to dryness.

Table 1

To the residue add 5 cmof hydrochloric acid and evaporated to dryness. Evaporation with hydrochloric acid is repeated twice using each time 5 cmof hydrochloric acid. Next, pour 20 cmof hydrochloric acid diluted 1:3 and heated to boiling. The solution was cooled, poured into a measuring flask with volume capacity given in table.1, made up to the mark with hydrochloric acid diluted 1:3 and stirred.

Pipetted 15 cmof the solution and placed in a test tube or cylinder with a capacity of 18−20 cm, add 0.2−0.3 g of iron powder, mix and leave for 40−45 minutes.

At the end of the time add 0.5 cmof the gelatin solution and then mixed. After 10 min the solution was filtered through a cotton swab, collecting the filtrate into the cell. Passed through a solution of nitrogen or argon and polarographic lead in the range from minus 0.25 to minus 0.65 In relative to the saturated calomel electrode.

Simultaneously carried polarographically series of solutions with known lead content.

The values of the wave height of sample solution is subtracted the value of the wave height of solution in the reference experiment.

2.3.2. For the preparation of series of solutions with known lead content in volumetric flasks with a capacity of 100 cmmeasured 0,2; 0,3; 0,4; 0,5; 1,0; 2,0; 3,0; 4,0; 5,0; 6,0 cmstandard solution of lead, which corresponds to 0,2; 0,3; 0,4; 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 and 6.0 mg of lead, adjusted with hydrochloric acid to the mark and then continue as specified in claim 2.3.1.

2.3.1, 2.3.2. (Changed edition, Rev. N 2).

2.4. Processing of the results

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

,

where wave height lead when polarographically the test solution minus the height of the wave lead in a control experiment, mm.

 — the volume of the analyzed solution, cm;

 — weight of tin, g;

 — the average value of the relations the wave heights obtained in polarography series of solutions of known lead concentrations for these solutions, mm·cm/g.

2.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence probability of 0.95 should not exceed the values given in table.2.

Table 2

(Changed edition, Rev. N 2).

Sec. 3. (Deleted, Rev. N 2).

4. ATOMIC ABSORPTION METHOD

4.1. The essence of the method

The method is based on dissolving the sample in a mixture of hydrofluoric and nitric acids with water and measuring the nuclear absorption of lead in the flame of acetylene-air at a wavelength 283,8 nm.

4.2. Apparatus, reagents and solutions

Spectrophotometer atomic absorption.

The PTFE beakers with a capacity of 50 cmor Cup platinum with a capacity of not less than 50 cm.

Nitric acid according to GOST 4461 and diluted 1:4.

Hydrofluoric acid according to GOST 10484.

Mix to dissolve; cook according to GOST 15483.2.

Lead at 3778 GOST and GOST 22861.

Solutions of lead standard.

Solution a: 0,5000 g of metallic lead is dissolved in 30 cmof nitric acid, diluted 1:4, heated to remove oxides of nitrogen, cooled, transferred into a measuring flask with volume capacity of 1000 cm, adjusted to the mark with water and mix.

1 cmof solution A contains 5·10g of lead.

Solution B: 20 cmsolution And placed in a volumetric flask with a capacity of 100 cm, adjusted to the mark with water and mix.

1 cmof a solution contains 1·10g of lead.

The polyethylene flask with a capacity of 50 cm.

Tin of high purity according to GOST

860.

4.1, 4.2. (Changed edition, Rev. N 2).

4.3. Analysis

4.3.1. Depending on the mass fraction of lead in the sample tin weight in accordance with table.5 were placed in a glass made of PTFE or platinum Cup with a capacity of 50 cmand poured in small portions to 10 cmof the mixture for dissolution. Then do as specified in GOST 15483.2. The solution is poured into a measuring flask with volume capacity given in table.5, pour the mixture for dissolving at the rate of 10 cmof a mixture of 50 cmvolume of solution, made up to the mark with water and mix.

Table 5*

________________

* Table.3, 4. (Deleted, Rev. N 2).

The obtained solution is sprayed in air-acetylene flame atomic absorption spectrometer and photometric at a wavelength 283,8 nm under the conditions specified in GOST 15483.2.

The concentration of lead set calibration schedule, fotometriya simultaneously with the analyzed solutions a series of solutions with known content of lead and Supervisory experience.

4.3.2. To build a calibration curve of thirteen glasses of PTFE or platinum cups is placed a portion of tin of high purity by mass in accordance with table.5, dissolved in 20 cmof the mixture for dissolution, making sure that the reaction did not proceed rapidly. After dissolving the contents of the beaker heated for 1−2 minutes, without boiling, and cooled. The solutions were transferred to volumetric flasks with a capacity of 100 cmand twelve of them measure 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 and 6.0 cmstandard solution B, which corresponds to 0,05; 0,1; 0,2; 0,3; 0,4; 0,5 and 0.6 mg of lead and 2,0; 3,0; 4,0; 5,0; 6,0 cmstandard solution A, which corresponds to 1,0; 1,5; 2,0; 2,5; 3,0 mg of lead. The solution volume in all flasks was adjusted to the mark with water and mix. Measure the atomic absorption of lead as specified in claim 4.3.1. According to the obtained values of the nuclear absorption and the corresponding lead concentrations to build a calibration curve.

4.3.1, 4.3.2. (Changed edition, Rev. N 2).

4.4. Processing of the results

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

,

where is the concentration fotometricheskogo solution, g/cm;

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

 — volume fotometricheskogo solution, cm;

 — weight of tin,

(Changed edition, Rev. N 1, 2).

4.4.2. Allowable absolute discrepancies in the results of parallel measurements at a confidence probability of 0.95 should not exceed the values given in table.2.

(Changed edition, Rev. N 2).