GOST 21877.9-76

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  ГОСТ 21877.9-76

GOST 21877.9−76 Babbit tin and lead. Methods for determination of cadmium (with Amendments No. 1, 2)

GOST 21877.9−76

Group B59

STATE STANDARD OF THE USSR

BABBIT TIN AND LEAD

Methods for determination of cadmium

Tin and lead babbits. Methods for the determination of cadmium*

AXTU 1709**
_______________
* The name of the standard. Changed the wording, Rev. N 2.
** Added, Rev. N 2.

Valid from 01.01.78.
to 01.01.83*
_______________________________
* Expiration removed
according to the Protocol of the Intergovernmental Council
for standardization, Metrology and certification
(IUS N 2, 1993). — Note the manufacturer’s database.

DEVELOPED by the Central research Institute for tin industry (Tsniiolovo)

Director V. A. Arsenico

Supervisor S. V. Meshkov

Executor G. V. Ivanova

INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

Zam. Minister N.N. Chepelenko

The draft all-Union scientific research Institute of standardization (VNIIS)

Director A. V. Gichev

APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from may 24, 1976 N 1264

REPLACE GOST 1380.7−70

MADE: the Change in N 1, approved and put into effect by the Decree of the USSR State Committee for standards from 14.02.83 N 805 with 01.07.83, Change No. 2, approved and put into effect by the Decree of the USSR State Committee for standards from 25.06.87 N 2463 with 01.03.88

Change N 1, 2 made by the manufacturer of the database in the text N 6 ICS 1983 ICS N 10 1987


This standard applies to tin and lead babbits and sets the polarographic method for the determination of cadmium content (if the cadmium content is from 0.01 to 1.2%) and volumetric chelatometric method for the determination of cadmium content (if the cadmium content of 0.8 to 1.2%) and atomic absorption method for determination of cadmium content (if the cadmium content is from 0.01 to 1.2%).

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 21877.0−76.

2. POLAROGRAPHIC METHOD FOR THE DETERMINATION OF CADMIUM

2.1. The essence of the method

The sample is dissolved in a mixture of hydrochloric, bromatological acid and bromine and distilled tin and antimony in the form of bromides. Remove lead chloride. Cadmium chloride polarographic on the background in the range of minus 0.7 to minus 1.1 V (relative to a saturated calomel electrode) applied voltage polarization.

2.2. Apparatus, reagents and solutions

Polarograph appropriate design dripping with mercury cathode.

Hydrochloric acid by the GOST 3118−77 and diluted 1:10.

Bromatologia acid according to GOST 2062−77.

Bromine according to GOST 4109−79.

Mix to dissolve: mix 45 cmof hydrochloric and 45 cmbromatological acid and carefully pour 10 cmof bromine.

Nitric acid GOST 4461−77 and diluted 1:1.

Ammonia according to GOST 3760−79.

Ammonium chloride according to GOST 3773−72.

Chloride-ammonia background: 135 g of ammonium chloride dissolved in a small amount of water is added 385 cmof concentrated ammonia solution, made up to 1 DMwith water and stirred.

Cadmium GOST 1467−77*.
________________
* Valid GOST 1467−93, here and hereafter. — Note the manufacturer’s database.

A standard solution of cadmium; prepared as follows: 1.0 g of cadmium is dissolved by heating in 10 cmof nitric acid, diluted 1:1. The solution was evaporated almost to dryness, add 7−10 cmof concentrated hydrochloric acid and evaporated to dryness. Treatment with hydrochloric acid again, and then add 60 cmof concentrated hydrochloric acid, transfer the solution into a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.

1 cmof the solution contains 1 mg of cadmium.

Sanitarily sodium (sodium sulfite) according to GOST 195−77, a freshly prepared solution of 200 g/DM.

Gelatin GOST 11293−78*, a solution of 10 g/DM.
__________________
* Valid GOST 11293−89, here and hereafter. — Note the manufacturer’s database.

Mercury GOST 4658−73, grade P1.

(Changed edition, Rev. N 1, 2).

2.3. Analysis

2.3.1. A portion of the babbit weighing 0.5 g were placed in a glass with a capacity of 250 cm, and dissolved in 10 cmof the mixture of acids and bromine. The solution was evaporated to dryness. The sludge treatment is repeated twice more, priliva 5 cmof the mixture. The dry residue moistened with 20 cm
hydrochloric acid diluted 1:10, boil to remove the bromine and cooled in running water. The precipitate of lead chloride is filtered off through the filter medium density, washed 5−6 times with hydrochloric acid diluted 1:10, chilled in the running water, and discard. The filtrate and washings neutralized with ammonia, is added 40 cmchloride-ammonia solution and stirred. The solution was cooled, transferred to a measuring flask with volume capacity of 1000 cm, flow 10 cmof a solution of sodium sulfite and leave for 20 minutes, then add 4 cmof a solution of gelatine, adjusted to the mark with water and mix.

After 10−15 minutes part of the solution was transferred into the electrolytic cell and polarographic at potentials from minus 0.7 to minus 1.1 V (relative to a saturated calomel electrode).

The cadmium content in percent is determined by comparing the wave height of cadmium obtained with the test solution polarographically, with the wave height obtained in polarography calibration solutions of cadmium, with the same sensitivity.

(Changed edition, Rev. N 1).

2.3.2. Preparation of the calibration solutions

In a volumetric flask with a capacity of 100 cmmake a 2.0; 6.0 and 10.0 cmof a standard solution of cadmium, which corresponds to the cadmium concentrations of 20, 60 and 100 mg/l, add 4 cmof concentrated hydrochloric acid, neutralized with ammonia and further analysis are as indicated in claim 2.3.1. Calibration solutions polarographic under the same conditions as the solutions of the tested samples.

(Changed edition, Rev. N 1).

2.4. Processing of the results

2.4.1. The contents of cadmium (a) in percent is calculated by the formula

,

where wave height obtained by polarography of test solution, mm;

 — volume of test solution, cm;

 — the mass of sample, g;

 — conversion factor calculated according to the formula

,

; ; ,

where , ,  — the height of waves, obtained by polarography calibration solutions, mm;

, , is the concentration of the calibration solutions of cadmium, mg/l.

(Changed edition, Rev. N 1).

2.4.2. Allowable absolute differences the results of the analysis shall not exceed the values given in table.1.

Table 1

(Changed edition, Rev. N 1, 2).

2.4.3. Polarographic method for the determination of cadmium is arbitration.

3. METHOD CHELATOMETRIC DETERMINATION OF CADMIUM

3.1. The essence of the method

The sample is dissolved in a mixture of hydrochloric, bromatological acids and bromine. Antimony and tin are distilled in the form of bromides. Cadmium titrated with Trilon B from aliquote part of the solution, copper is bound by a thiourea.

3.2. Reagents and solutions

Hydrochloric acid by the GOST 3118−77.

Bromatologia acid according to GOST 2062−77.

Bromine according to GOST 4109−79.

Mix to dissolve: mix 45 cmof hydrochloric and 45 cmbromatological acid and carefully pour 10 cmof bromine.

Nitric acid GOST 4461−77.

Hydrogen peroxide according to GOST 10929−76.

Thiourea according to GOST 6344−73, a solution of 100 g/DM.

Methenamine medical, 20% solution.

On-fenantrolin, a solution of 10 g/DM; prepared as follows: 1 g o-phenanthroline dissolved in 100 cmof warm water with 2−3 drops of nitric acid.

Selenology orange, water, freshly prepared solution of 1 g/DM.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, the solution concentration of 0.01 mol/l; prepared as follows: 4.0 g Trilon B dissolved in water. If the solution is turbid, it is filtered and diluted with water to 1 DM.

Lead nitrate solution of concentration 0.01 mol/l; prepared as follows: 2,0721 g of metallic lead brand WITH GOST 3778−77* placed in a beaker with a capacity of 250 cmand dissolved in 25 cmof nitric acid. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.
_____________
* Valid GOST 3778−98. — Note the manufacturer’s database.

A standard solution of cadmium; prepared as follows: 1.0 g of cadmium GOST 1467−77 placed in a beaker with a capacity of 250 cm, was dissolved with heating in 25 cmof nitric acid, cooled, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.

1 cmof the solution contains 0.001 g of cadmium.

(Changed edition, Rev. N 1, 2).

3.3. Analysis

3.3.1. Chelatometric determination of cadmium without separation of copper and lead by electrolysis

A portion of the Babbitt weight of 1.0 g were placed in a glass with a capacity of 250 cmand 15 cm pour themixture to dissolve.

The solution was evaporated until the appearance of the wet salts, add 5 cmof the mixture and evaporated to dryness. Repeat the process two more times, priliva 5 cmof the mixture. To the dry residue poured 5cmof hydrochloric acid, 1 to 3 drops of hydrogen peroxide and evaporated to dryness. Treatment of the precipitate with hydrochloric acid and peroxide is repeated three times.

To the residue was poured 5cmof hydrochloric acid and evaporated to dryness. After complete distillation of bromine dry residue moistened with 2 cmof nitric acid, pour the 20−30 cmof water and heated to dissolve the salts, then cooled, transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with water and mix.

Select the 10 cmmortar, transferred to a conical flask with a capacity of 250 cm, add 50 cmof water, 10 cmof a solution of thiourea, in small portions pour the solution of hexamine to bright-purple color (pH 5,4−5,8), then pour 2−3 cmof solution of nitrate of lead, and titrated from microburette solution of Trilon B till the yellow colour (this titration is not taken into account).

In a flask pour 10 cmof a solution of o-phenanthroline and titrated from microburette solution of nitrate of lead until the purple color, and then poured a little of the solution in excess. An excess of solution of nitrate of lead octarepeat from microburette solution of Trilon B till the transition of color in yellow-green.

(Changed edition, Rev. N 1, 2).

3.3.1.1. Chelatometric determination of cadmium after separation of copper and lead by electrolysis

A portion of the babbit B88 brand weighing 1.0 g was placed in a beaker with a capacity of 250 cmand 15 cm pour themixture to dissolve. The solution was evaporated to wet salts, add 5 cmof the mixture and evaporated to dryness. Repeat the process two more times, priliva 5 cmof the mixture. To the dry residue poured 20 cmof nitric acid, diluted 1:1, and boil to remove the bromine. The residue is diluted with water to 150−180 cmand by isolation of copper and lead by electrolysis according to GOST 21877.3−76, p.2.3.2.

After electrolysis, the solution was transferred to volumetric flask with a capacity of 250 cm, is diluted to the mark with water and mix.

In a flask with a capacity of 200 cm25 cm select thesolution, add 25 cmof water, 2 cmof thiourea, xianbao 2−3 drops of orange and small portions of the hexamine to pH 5.5 and 5.8 (solution turns crimson). Then the solution was poured 2 cmTrilon B concentration 0.01 mol/DM, and a bit of hexamine solution, painted in yellow, titrated solution of nitrate of lead in a concentration of 0.01 mol/DMbefore the transition of color in the yellow-pink color.

To the solution add 2 cmOn-fenantrolina, stirred and titrated again painted yellow solution with a solution of nitrate of lead in a concentration of 0.01 mol/luntil the color changes to yellow-pink.

(Added,

Izm. N 2).

3.3.2. The installation of the mass concentration of nitrate of lead by cadmium

Mass concentration of solution of nitrate of lead set by the standard solution of cadmium.

Pipetted or microburette 5 cmstandard solution of cadmium and titrated as described in section 3.3.1.

Mass concentration of solution of nitrate of lead () for cadmium, expressed in g/cm, is calculated by the formula

,

where  — the weight of the portion of cadmium in aliquote part of the solution, g;

 — the total volume of solution of nitrate of lead consumed in the second titration, cm;

 — volume of solution Trilon B, used for titration of excess of solution of nitrate of lead, cm;

 — a correction factor characterizing the ratio of the nitrate solution of lead, and Trilon B.

For installation of the correction factor poured into the flask from microburette 3 or 5 cmof a solution of nitrate of lead is added 40 cmof water, a few drops kylinalove orange, solution of hexamine until the appearance of crimson colour (pH 5,4−5,8) and titrated from microburette solution of Trilon B to switch the color to yellow.

The correction factor is calculated by the formula

,

where is the volume of solution of nitrate of lead, taken for titration, cm;

 — volume of solution Trilon B, spent on titration, sm.

(Changed edition, Rev. N 1, 2).

3.4. Processing of the results

3.4.1. The contents of cadmium (a) in percent is calculated by the formula

,

where is the total volume of the solution of nitrate of lead consumed in the second titration, cm;

 — volume of solution Trilon B, used for titration of excess of solution of nitrate of lead, cm;

 — correction factor (see p.3.3.2);

 — aliquota part of the solution, cm;

 — volume of test solution, cm;

 — mass concentration of solution of nitrate of lead by cadmium, g/cm;

 — the weight of the portion of the sample,

(Changed edition, Rev. N 1, 2).

3.4.2. Allowable absolute differences the results of the analysis shall not exceed 0.10%.

(Changed edition, Rev. N 2).

4. ATOMIC ABSORPTION METHOD FOR DETERMINATION OF CADMIUM

4.1. The essence of the method

The method is based on selective absorption of light from a standard source of cadmium atoms. The solution is sprayed in an acetylene-air flame atomic absorption spectrometer and measure the absorbance at a wavelength of 228,8 nm.

4.2. Apparatus, reagents and solutions

Spectrometer of atomic absorption.

The glasses are made of PTFE with a capacity of 50 cm.

Hydrofluoric acid according to GOST 10484−78.

The mixture of acids to dissolution; hydrofluoric and nitric acid is mixed with water in the ratio 2:3:5 respectively; stored in a plastic container.

Cadmium GOST 1467−77.

A standard solution of cadmium; prepared as follows: 0,1000 g of cadmium is dissolved by heating in 20 cmof nitric acid, diluted 1:1, and boil to remove oxides of nitrogen. The solution was cooled, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmof the solution contains 0.1 mg of cadmium.

4.3. Analysis

4.3.1. Depending on the content of cadmium in the sample Babbitt mass, given in table.2, is placed in a beaker made of PTFE with a capacity of 50 cmand poured in small portions to 10 cmof the mixture for dissolution. Further analysis is carried out according to GOST 21877.3−76.

Table 2

Fotometrirovanie is carried out at a wavelength of 228,8 nm according to the conditions specified in GOST 21877.3−76. The cadmium concentration set at the calibration schedule, fotometriya simultaneously with the analyzed solutions a series of solutions with known content of cadmium.

4.3.2. To build a calibration curve in a volumetric flask with a capacity of 50 cm, measure off microburette 0; 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution of cadmium pour 10 cmof the mixture for dissolution, adjusted to the mark with water and mix. Photometric solutions as well as solutions of the analyzed samples.

According to the obtained average values of absorption and the known content of cadmium build the calibration graph.

4.4. Processing of the results

4.4.1. The contents of cadmium (a) in percent is calculated by the formula

,

where is the concentration fotometricheskogo solution, µg/cm;

 — volume fotometricheskogo solution, cm;

 — the weight of the portion of the babbit, g;

 — conversion factor from micrograms to grams.

4.4.2. Allowable absolute differences the results of the analysis at a confidence level of 0.95, should not exceed the values given in table.3.

Table 3