GOST 1652.2-77
GOST 1652.2−77 Alloys copper-zinc. Methods for determination of lead (with Amendments No. 1, 2, 3)
GOST 1652.2−77
Group B59
STATE STANDARD OF THE USSR
ALLOYS COPPER-ZINC
Methods for determination of lead
Copper-zinc alloys. Methods for the determination of lead
AXTU 1709
Date of introduction 1978−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
DEVELOPERS
Y. F. Chuvakin, M. B. Taubkin, A. A. Nemodruk, N. In. Egiazarov (supervisor), I. A. Vorobyev
2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from
3. REPLACE GOST 1652.2−71
4. The standard fully complies with ISO 4749−84*
________________
* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link to the site shop.cntd.ru. — Note the manufacturer’s database.
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced | The number of the paragraph, subparagraph |
| GOST 8.315−91 |
2.4.4, 3.4.4, 4.4.4, 5.4.4, 6.4.4 |
| GOST 859−78 |
5.2 |
| GOST 1020−77 |
Chapeau |
| GOST 1652.1−77 |
1.1 |
| GOST 2062−77 |
3.2 |
| GOST 2210−73 |
3.2 |
| GOST 3117−78 |
2.2 |
| GOST 3118−77 |
2.2, 4.2, 5.2 |
| GOST 3760−79 |
3.2, 4.2 |
| GOST 3773−72 |
4.2 |
| GOST 3778−77 |
2.2, 4.2, 5.2 |
| GOST 4109−79 |
3.2, 4.2 |
| GOST 4147−74 |
3.2 |
| GOST 4166−76 |
4.2, 5.2 |
| GOST 4204−77 |
2.2, 3.2, 5.2 |
| GOST 4207−75 |
2.2 |
| GOST 4233−77 |
2.2 |
| GOST 4328−77 |
4.2 |
| GOST 4461−77 |
2.2, 3.2, 4.2, 5.2, 6.2 |
| GOST 4658−73 |
3.2 |
| GOST 5475−69 |
5.2 |
| GOST 5817−77 |
4.2 |
| GOST 6563−75 |
6.2 |
| GOST 8864−71 |
4.2 |
| GOST 9293−74 |
3.2 |
| GOST 10484−78 |
5.2 |
| GOST 10652−73 |
2.2 |
| GOST 10929−76 |
3.2 |
| GOST 14261−77 |
3.2 |
| GOST 15527−70 |
Chapeau |
| GOST 17711−93 |
Chapeau |
| GOST 18300−87 |
2.2, 4.2 |
| GOST 25086−87 |
1.1, 2.4.4, 3.4.4, 4.4.4, 5.4.4, |
6. Resolution of the state standard from
7. REVISED (June 1997) with Amendments No. 1, 2, 3 approved in November 1987, October 1990, December 1992 (ICS 2−88, 2−90, 3−93)
This standard establishes titrimetric and electrogravimetry methods for determination of lead (with a mass fraction of lead from 0.5 to 5%), a polarographic method for the determination of lead (with a mass fraction of lead from 0.001 to 5%), a photometric method for the determination of lead (from 0.005 to 1.0%) and atomic absorption method for the determination of lead (from 0.005 to 5.0%) in copper-zinc alloys according to GOST 15527, GOST and GOST 17711 1020.
The standard fully complies with ISO 4749.
(Changed edition, Rev. N 2).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 25086 with the Supplement according to claim 1.1 GOST 1652.1.
(Changed edition, Rev. N 1).
2. TITRIMETRIC CHELATOMETRIC METHOD FOR THE DETERMINATION OF LEAD
2.1. The essence of the method
The method is based on titration of lead at pH 5.5−6.0 with a solution of Trilon B in the presence kylinalove orange as an indicator to the transition of color from purple to yellow.
2.2. Apparatus, reagents and solutions
Sulfuric acid according to GOST 4204, diluted 1:1 and 1:50.
Nitric acid according to GOST 4461 and diluted 1:1.
Hydrochloric acid according to GOST 3118.
A mixture of nitric and hydrochloric acids; prepared as follows: one volume of nitric acid mixed with three volumes of hydrochloric acid.
The technical rectified ethyl alcohol according to GOST 18300.
Potassium ferrocyanide according to GOST 4207, a solution of 30 g/DM.
Ammonium acetate according to GOST 3117, a solution of 250 g/DM.
Lead brands S0 GOST 3778.
Indicator kylinalove orange, the drug is mixed with sodium chloride in a ratio of 1:100, well pounded.
Sodium chloride according to GOST 4233.
Salt is the disodium Ethylenediamine-,
,
,
-tetraoxane acid 2-water (Trilon B) according to GOST 10652, 0,025 mol/DM
solution; prepared as follows: 9,305 g Trilon B dissolved in 500 cm
of water when heated, transferred to a volumetric flask with a capacity of 1 DM
and topped to the mark with water.
(Changed edition, Rev. N 2).
THE INSTALLATION OF THE MASS CONCENTRATION OF THE SOLUTION TRILON B
0.1 g of lead dissolved in 15 cm.of nitric acid diluted 1:1, poured 40 cm
of sulphuric acid diluted 1:1, and evaporated until a white smoke of sulfuric acid. The solution was cooled, washed walls of glass with water and repeat the evaporation until a white smoke of sulfuric acid. The solution was then cooled, poured 150 cm
of water and heated to boiling, then cooled, poured in 40 cm
ethanol and left for 4 h. Further analysis is carried out as specified in clause
Mass concentration of the solution Trilon B (), expressed in grams of lead per 1 cm
of a solution, calculated by the formula
where is the mass of the lead sample, g;
— volume of solution Trilon B, spent on titration, sm
.
2.3. Analysis
2.3.1. For alloys not containing silicon
2 g of alloy are placed in a beaker with a capacity of 300 cm, cover with a watch glass and dissolved in 15 cm
of the mixture of acids when heated. After dissolution of the alloy wash glass, poured 40 cm
of sulphuric acid diluted 1:1, evaporated until a white smoke of sulfuric acid. The solution was cooled, the side of the Cup washed with water and evaporated again until a white smoke of sulfuric acid.
The residue is cooled, poured 150 cmof water, heated to boiling and cooled again. Then pour 40 cm
ethanol and left for 4 h. the Separated precipitate of lead sulphate filtered off on a tight filter, the beaker rinsed with sulfuric acid, diluted 1:50, and the precipitate washed with the same acid until the complete removal of bivalent copper (test with potassium ferrocyanide), and then two or three times with water. The filter with precipitate was placed in a beaker, in which was conducted the deposition. Pour 15 cm
of a solution of acetate of ammonia, heated to boiling and boiled for 2 min.
The solution is poured into a conical flask with a capacity of 250 cm. The glass filter is poured twice at 30 cm
of hot water, each time pouring the solution into the same flask. Back in the beaker with filter pour 15 cm
of a solution of acetate of ammonia and repeat the process filter.
In the received solution add a little (tip of spatula) mix kylinalove orange with sodium chloride and titrated with a solution of Trilon B to a transition of a purple color to yellow
th.
2.3.2. For alloys containing silicon
2 grams of the alloy placed in a platinum Cup and dissolved in 15 cm.of nitric acid diluted 1:1 and 1 cm
hydrofluoric acid. After dissolution of the alloy solution was cooled, poured 40 cm
of sulphuric acid diluted 1:1, and evaporated until a white smoke of sulfuric acid. The solution was cooled, rinse the walls of the Cup with water and evaporated again until a white smoke of sulfuric acid. The residue is cooled, salts are dissolved in water and transferred the solution into a glass with a capacity of 250 cm
. Rinse the Cup with water so that the volume does not exceed 150 cm
. The solution is heated and further analysis are as indicated in claim
2.4. Processing of the results
2.4.1. Mass fraction of lead (a) percentage calculated by the formula
where — volume of solution Trilon B, spent on titration, sm
;
— mass concentration of the solution Trilon B, g/cm
;
— the weight of the portion of alloy,
2.4.2. Allowable absolute discrepancies in the results of parallel measurements ( — convergence) must not exceed the values given in table.1.
Table 1
| Mass fraction of lead, % |
|
|
| From 0.001 to 0.003 incl. |
0,0002 |
0,0003 |
| SV. Of 0.003 «to 0.005 « |
0,0005 |
0,0007 |
| «0,005» 0,010 « |
0,001 |
0,0014 |
| «Of 0.010» to 0.025 « |
0,0025 |
0,0035 |
| «0,025» 0,050 « |
0,004 |
0,006 |
| «To 0.05» and 0.12 « |
0,01 |
0,014 |
| «0,12» 0,60 « |
0,02 |
0,03 |
| «To 0.6» to 1.5 « |
0,04 |
0,05 |
| «To 1.5» and 5.0 « |
0,08 |
0,11 |
(Changed edition, Rev. N 2, 3).
2.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (the reproducibility) shall not exceed the values given in table.1.
2.4.4. The control accuracy of the analysis carried out according to State standard samples (GSO) or industry standard sample (CCA), or by standard samples of the enterprise (SOP) copper-zinc alloys, approved GOST 8.315, or by additives, or by comparing the results obtained by another method in accordance with GOST 25086.
2.4.3,
3. POLAROGRAPHIC METHOD FOR THE DETERMINATION OF LEAD
3.1. The essence of the method
The method is based on preliminary separation of lead from primary metals by coprecipitation with ferric hydroxide in ammoniacal solution with subsequent determination of lead by a polarographic method.
3.2. Apparatus, reagents and solutions
Polarograph type 5122 or PTT-1, or any other polarograph AC.
The polarographic cell, made of glass, with external electrode (saturated calomel electrode) and mercury-drip cathode.
Hydrochloric acid according to GOST 14261, diluted 1:1, and 5% solution.
Nitric acid according to GOST 4461, diluted 1:1.
Perchloric acid, h. e. a.
Bromatologia acid according to GOST 2062.
Bromine according to GOST 4109.
Mix to dissolve, freshly made: nine volumes bromatological acid is mixed with one volume of bromine.
Ammonia water according to GOST 3760 and 2% solution.
Iron chloride according to GOST 4147, a solution of 10 g/DMin a 5% strength solution of hydrochloric acid.
Lead brands S0 GOST 3778.
Standard solutions of lead
Solution A, prepared as follows: 0.1 g of lead is dissolved by heating in 30 cmof nitric acid is removed by boiling the oxides of nitrogen, cooled, poured 50 cm
of water, transfer the solution into a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
1 cmof the solution contains 0.0001 g of lead.
Solution B is prepared as follows: 10 cmof solution A is placed in a volumetric flask with a capacity of 100 cm
, add 2 cm
of concentrated hydrochloric acid, made up to the mark with water and mix.
1 cmof solution B has the 0.00001 g of lead; prepared immediately before use.
Mercury brands r0 according to GOST 4658, dehydrated.
Nitrogen gas according to GOST 9293.
Hydrogen peroxide according to GOST 10929, 30% solution.
Ascorbic acid.
Gelatin solution 5 g/DM(freshly made).
A mixture of acid: concentrated nitric and hydrochloric acids in a ratio of 1:3.
Ammonium chloride according to GOST 2210.
(Changed edition, Rev. N
2).
3.3. Analysis
3.3.1. For all alloys containing tin less than 0.05%
A portion of the alloy (tab.2) is placed in a beaker with a capacity of 250 cm, cover with a watch glass and gently dissolved in 20 cm
of the mixture for dissolution. With incomplete dissolution in the beaker was added dropwise bromine. Poured to a solution of 20 cm
of perchloric acid and evaporate the solution to lighten and the appearance of dense white smoke of perchloric acid (total volume, the remaining solution should not exceed 5 cm
).
Table 2
| Mass fraction of lead in the alloy, % |
The mass of charge, g |
Polarografic the volume of solution, cm |
| From 0.001 to 0.003 incl. |
1 |
40 |
| SV. Of 0.003 «to 0.01 « |
1 |
20 |
| «To 0.01» to 0.025 « |
1 |
10 |
| «Of 0.025» to 0.05 « |
0,5 |
5 |
| «0,05» 0,1 « |
0,5 |
2 |
| «0,1» 0,5 « |
0,1 |
5 |
| «0,5» 2,5 « |
0,1 |
2 |
| Of «2.5 «5 « |
0,1 |
1 |
Cool the beaker, wash the side of the Cup a small amount of water, heated to dissolve the salts and add water up to 100−150 cm.
3.3.2. For alloys containing tin over 0.05%
A portion of the alloy by weight (table.2) is placed in a beaker with a capacity of 250 cm, add 20 cm
of a mixture of acids and dissolved by heating. After dissolution the solution is cooled and added water up to 100−150 cm
.
3.3.3. To the obtained solution (see section 3.3.1 and 3.3.2) pour 1 cmof solution of ferric chloride (at a mass fraction of iron in the alloy is less than 0.5%), add 3 g of ammonium chloride and ammonia solution until the staining solution in a dark blue color, and beyond that another 5 cm
of ammonia solution and maintained at 60−70°C for 20 min.
The precipitate was filtered off on a filter of medium density. The glass and the filter cake was washed 3−4 times with hot 2% solution of ammonia. The funnel with the precipitate was placed on glass, which made the deposition, the precipitate was dissolved in 20 cmof hot hydrochloric acid, diluted 1:1, adding a few drops of hydrogen peroxide in the presence in the alloy of manganese.
The filter is washed with 30 cmof hot water, the solution was diluted to a 125−150 cm
and repeat the precipitation.
After dissolving the precipitate in 20 cmof hot hydrochloric acid (1:1), the filter was washed 6 times with hot water, add 3−5 cm
of hydrogen peroxide and evaporated to dryness. To the dry residue add 5 cm
of hydrochloric acid (1:1), 3 cm
of hydrogen peroxide and repeat the evaporation. The cooled residue is dissolved in 5 cm
of hydrochloric acid, the solution transferred to a volumetric flask with a capacity of 50 cm
, add 0.5 cm
of the solution of gelatin and ascorbic acid to the disappearance of the yellow color of ferric iron. The solution was topped to the mark with water and mix.
Simultaneously with the determination of lead in the alloy conduct control experience with all reagents described above met
odice.
3.3.4. Taken from the flask aliquot part of the solution (see table.2) and transferred to a polarographic cell, dilute with water to 20 cmfor the mass concentration of lead above 0.01%. The solution in the cell is degassed flowing nitrogen for 5−7 min, stop stirring and remove the cathodic polarization curve in the voltage range from minus 0.3 to minus 0.7 V. the Peak recovery of lead observed in the field minus 0,45 V. the Sensitivity of the recording instrument is selected so that the peak of lead was at least 15 mm.
3.3.5. Lead find by the method of standard additions. Aliquot part of the solution A or B, depending on the content of lead, added to polarographically solution, stirred solution of 3 min and further analysis are as under determination of lead in test solution (see p.3.3.4).
The value of the standard additives is chosen so that the peak height of lead after introduction of the additive increased 1.5−2 times.
3.3.1−3.3.5. (Changed edition, Rev. N 2).
3.4. Processing of the results
3.4.1. Mass fraction of lead (a) percentage calculated by the formula
where is the peak height of lead in polarography solution in the reference experiment, mm.
the peak height of lead in polarography of test solution, mm;
— the height of the peak of the lead after the introduction of standard additives, mm;
— the volume of standard addition, mm;
— concentration of standard solution, g/cm
;
— the weight of the portion of the alloy taken for polarographically, g
.
3.4.2. The absolute discrepancies in the results of parallel measurements ( — convergence) must not exceed the permissible values given in table.1.
(Changed edition, Rev. N 1, 3).
3.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (the reproducibility) shall not exceed the values specified in table.1.
3.4.4. The control accuracy of the analysis carried out according to State standard samples (GSO) or industry standard sample (CCA), or by standard samples of the enterprise (SOP) copper-zinc alloys, approved GOST 8.315, or by additives, or by comparing the results obtained by another method in accordance with GOST 25086.
3.4.3,
4. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF LEAD
4.1. The essence of the method
The method is based on extraction of lead from alkaline tartrates environment of chloroform in the form of diethyldithiocarbaminate, the substitution of the extract of lead, copper, shaking the extract with an excess of water solution of sulfate of copper and optical density measurements obtained chloroform solution diethyldithiocarbaminate copper.
4.2. Apparatus, reagents and solutions
Photoelectrocolorimeter or spectrophotometer.
Tartaric acid according to GOST 5817, a solution of 400 g/DM.
Hydrochloric acid according to GOST 3118 and diluted 1:1.
Nitric acid according to GOST 4461 and diluted 1:1.
Sodium hydroxide according to GOST 4328, a solution of 500 g/DM.
Ammonia water according to GOST 3760 and diluted 1:50.
Diethyldithiocarbaminate sodium GOST 8864, aqueous solution 10 g/DM.
Phenolphthalein, solution at 10 g/lin ethanol.
The technical rectified ethyl alcohol according to GOST 18300.
Anhydrous copper sulfate solution 50 g/DM.
Chloroform.
Lead according to GOST 3778, brand C0.
Standard solutions of lead
Solution A, prepared as follows: 0.1 g of lead dissolved in 20 cmof nitric acid, diluted 1:1, when heated. After removal of oxides of nitrogen by boiling the solution 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 0.0001 g of lead.
Solution B is prepared as follows: transfer 10 cmof solution A in a volumetric flask with a capacity of 100 ml, made up to the mark with water and mix.
1 cmof solution B has the 0.00001 g of lead.
Ammonium chloride according to GOST 3773.
Sodium sulphate anhydrous according to GOST 4166.
Iron, standard sample No. 126 (low carbon steel).
The solution of nitrate of iron; prepared by dissolving 1,005 g of the standard sample N 126 15 cmof concentrated nitric acid followed by diluting the solution with water up to 1 DM
.
1 cmof the solution contains 0.001 g of iron.
The acid chloride.
Bromatologia acid according to GOST 2062.
Bromine according to GOST 4109.
Mix to dissolve, freshly prepared: mix bromatological acid with bromine in a ratio of 9:1.
(Revised edition, Edit
. N 2).
4.3. Analysis
4.3.1. A sample of alloy weighing 1 g is placed in a beaker with a capacity of 250 cm, and dissolved in 20 cm
of nitric acid, diluted 1:1, and 2 cm
of hydrochloric acid. The solution is diluted with water to 150 cm
, add 5 g of ammonium chloride and 30 cm
of a solution of nitrate of iron (for alloys with a mass fraction of less than 0.5% of iron) is heated to 80−90°C and ammonia is added to the transfer of all the copper in the soluble ammonia complex. Upset give koagulirovat in a warm place for 20−30 min, after which the precipitate was filtered off on a medium density filter and washed free of copper with hot solution of ammonia, diluted 1:50. The precipitate is dissolved in 10 cm
of hot nitric acid diluted 1:1, and repeat the precipitation of the hydroxides dissolution and washing the precipitate until the disappearance of the copper ions in the filtrate (sample with sodium diethyldithiocarbamate in chloroform).
The precipitate is dissolved in 10 cmof hot nitric acid diluted 1:1 in a glass, which made the deposition, and boil to remove oxides of nitrogen. When lead content less than 0.01% to the extraction using the full solution with lead content of more than 0.01% and the solution transferred to a volumetric flask with a capacity of 250 cm
, made up to the mark with water and mix. Aliquot part of the solution is 25 cm
(with mass fraction of lead from 0.01 to 0.05%), 10 cm
(with a mass fraction of lead from 0.05 to 0.2%) or 5 cm
(when the mass fraction of lead from 0.2 to 0.5%) or 2,5 cm
(with a mass fraction of lead from 0.5 to 1%) is transferred to a separatory funnel with a capacity of 250 cm
. The solution in the funnel is diluted with water to 100 cm
, add 15 cm
of a solution of tartaric acid, neutralized with sodium hydroxide solution to phenolphthalein before occurrence of pink coloring and on top of this add another 3−5 cm
of sodium hydroxide solution. Then add 5 cm
of a solution of sodium diethyldithiocarbaminate, 15 cm
of chloroform, and extracted the lead in the form of diethyldithiocarbaminate, shaking 5 min, the Lower chloroform layer is drained into another separatory funnel so that the funnel did not get an aqueous solution. To the remaining aqueous phase add 5 cm
of chloroform and shaken for 3 min Chloroform layer is attached to the main extract and add 20 cm
of a solution of copper sulphate and shake for 5 min. Painted the chloroform layer was transferred into a measuring flask with a capacity of 25 cm
, which has added 0.2 g of sodium sulfate. The chloroform solution in the volumetric flask, add chloroform to the mark, and measure optical density of the solution on the spectrophotometer in a cuvette with a layer thickness of 1 cm at a wavelength of 435 nm or photoelectrocolorimeter in a cuvette with a layer thickness of 1 or 2 cm with a blue filter. Solution comparison is the solution of the reference experiment.
(Modified …
tion, Rev. N 2).
4.3.1 a. When the mass fraction of tin in the alloy more than 0.1% of the weighed sample mass of 1 g was placed in a beaker with a capacity of 300 cm, add 20 cm
of the mixture for dissolution, and dissolved by heating. In case of incomplete dissolution of the added bromine dropwise. Then add 10−15 cm
of perchloric acid and evaporate the solution to lighten and the appearance of dense white smoke of perchloric acid (total volume, the remaining solution should not exceed 5 cm
). After cooling, rinse walls of beaker with water, heated to dissolve the salts, the solution is diluted with water to a volume of 150 cm
, add 5 g of ammonium chloride and then act as described in section
(Added, Rev. N 2).
4.3.2. Construction of calibration curve
In a separating funnel with a capacity of 250 cmmake 0; 1,0; 2,0; 3,0; 5,0; 7,0 and 10.0 cm
standard solution B, dilute with water to 100 cm
, is added to 15 cm
of a solution of tartaric acid and further analysis are as indicated in claim
4.4. Processing of the results
4.4.1. Mass fraction of lead (a) percentage calculated by the formula
where is the mass of lead was found in the calibration schedule g;
— the weight of the portion of alloy,
4.4.2. The absolute discrepancies in the results of parallel measurements ( — convergence) must not exceed the permissible values given in table.1.
(Changed edition, Rev. N 1, 3).
4.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (the reproducibility) shall not exceed the values specified in table.1.
4.4.4. The control accuracy of the analysis carried out according to State standard samples (GSO) or industry standard sample (CCA), or by standard samples of the enterprise (SOP) copper-zinc alloys, approved GOST 8.315, or by additives, or by comparing the results obtained by another method in accordance with GOST 25086.
4.4.3,
5. ATOMIC ABSORPTION METHOD
5.1. The essence of the method
The method is based on dissolving the sample in nitric acid or in a mixture of nitric and hydrochloric acids and the measurement of atomic absorption of lead in the flame of acetylene-air at a wavelength is 283.3 nm.
5.2. Apparatus, reagents and solutions
The atomic absorption spectrometer.
Lamp with a hollow cathode or other source of resonance radiation for the lead.
Nitric acid according to GOST 4461 and diluted 1:1.
Hydrochloric acid according to GOST 3118.
A mixture of nitric and hydrochloric acids in a ratio of 1:3.
Hydrofluoric acid according to GOST 10484.
Acetylene according to GOST 5475.
Lead according to GOST 3778.
Standard solution of lead: 1 g of lead is dissolved by heating in 10 cmof nitric acid (1:1). The solution was cooled, transferred to a measuring flask with volume capacity of 1000 cm
and top up with water to the mark.
1 cmof the solution contains 0.001 g of lead.
Copper according to the GOST 859.
Standard copper solution: 10 g of copper was dissolved with heating in 80 cmof nitric acid (1:1). The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
and top up with water to the mark.
1 cmof the solution contains 0.1 g of copper.
5.3. Analysis
5.3.1. In the determination of lead using the sample of the alloy given in table.3.
Table 3
| Mass fraction of lead, % |
The weight of the portion of the alloy, g |
The amount of acid for dissolution, cm |
| From 0.005 to 0.05 incl. |
3 |
30 |
| SV. Of 0.05 «to 0.2 « |
1 |
15 |
| «0,2» 5 « |
0,1 |
10 |
(Changed edition, Rev. N 2).
5.3.2. Analysis of alloys not containing tin and silicon
A portion of the alloy is dissolved when heated in nitric acid (1:1) (see table.3). The solution was cooled, transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark.
5.3.3. Analysis of alloys containing tin
A portion of the alloy is dissolved by heating in a mixture of acids (see table.3). The solution was cooled, transferred to a volumetric flask with a capacity of 100 cmand top up with water to the mark.
5.3.4. Analysis of alloys containing silicon
A portion of the alloy placed in a platinum Cup and dissolved when heated in nitric acid (1:1) (see table.3) and 3 cmhydrofluoric acid. The solution is evaporated to a volume of 3−4 cm
, flow 10 cm
of nitric acid (1:1) and again evaporated to a volume of 3−4 cm
. The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm
and top up with water to the mark.
5.3.5. Preparation of the calibration solutions
In eleven of the twelve volumetric flasks with a capacity of 100 cmplaced 0,1; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0; 4,5 and 5.0 cm
of a standard solution of lead, which corresponds to 0,1; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0; 4,5 and 5.0 mg of lead. If the weight of the portion of the alloy is 1 g or 3 to all flasks add 10 or 30 cm
of standard copper solution and add water to the mark.
5.3.6. Measure the atomic absorption of lead in solutions of the analyzed alloys and in the calibration solutions, recording the analytical signals. According to the obtained values build the calibration graph.
5.4. Processing of the results
5.4.1. Mass fraction of lead (a) percentage calculated by the formula
where is the concentration of lead in the sample solution alloy, was found in the calibration schedule, g/cm
;
— the concentration of lead in solution in the reference experiment, was found in the calibration schedule, g/cm
;
— the volume of the analyzed solution, cm
;
— weight alloy, g
.
5.4.2. The absolute discrepancies in the results of parallel measurements ( — convergence) must not exceed the permissible values given in table.1.
5.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (the reproducibility) shall not exceed the values specified in table.1.
5.4.4. The control accuracy of the analysis carried out according to State standard samples (GSO) or industry standard sample (CCA), or by standard samples of the enterprise (SOP) copper-zinc alloys, approved GOST 8.315, or by additives, or by comparing the results obtained by another method in accordance with GOST 25086.
5.4.2−5.4.4. (Changed edition, Rev. N 3).
6. ELECTROGRAVIMETRY METHOD FOR THE DETERMINATION OF LEAD
6.1. The essence of the method
The method is based on the release of lead electrolytically in the form of its dioxide at the anode and weighing the separated precipitate of dioxide of lead.
6.2. Equipment, reagents, solutions
Electrolysis installation DC.
Platinum mesh electrodes according to GOST 6563.
Nitric acid according to GOST 4461, diluted 1:1 and 1:100.
6.3. Analysis
6.3.1. Analysis of alloys not containing the tin
A sample weighing 0.5 g were placed in a glass with a capacity of 250 cm, adding 10 cm
of nitric acid (1:1), cover with watch glass, glass or plastic plate and dissolved by heating. After dissolution of the alloy and removal of nitrogen oxides or glass plate and the walls of the beaker rinse with water, add 15 cm
of nitric acid (1:1), dilute the solution up to 100−150 cm
water.
In the weighted solution is immersed an anode and a cathode and conducting electrolysis with a current of 1.5−2 And while stirring the solution. The glass electrolyte must be covered by the two halves of the hour glass or plastic plate with holes for electrodes and stirrer. After 30 min from the start of the electrolysis is removed or the glass plate, rinsed with water, and continue the electrolysis for 15 min. If after that svezhemorozhenoj in the solution part of the anode is not allocated sediment, the electrolysis is complete. Without turning off the current, quickly remove the beaker with the electrolyte and washed electrodes, substituting in turn the three cups with distilled water. Current is turned off, remove the anode and the precipitate of dioxide of lead, dry it at 160−170°C for 20 — 30 minutes to constant weight, cooled and weighed.
6.3.2. Analysis of alloys containing tin
A sample weighing 0.5 g were placed in a glass with a capacity of 250 cm, add 15 cm
of nitric acid (1:1), cover with watch glass, glass or plastic plate and dissolved by heating. After dissolution of the alloy or glass plate and the side of the Cup then rinsed with water and the solution was boiled down to 5−10 cm
. To the residue add 60−70 cm
of hot water and solution and the precipitate was kept at 60−70°C in a warm place or in a water bath for 1 h. the Precipitate metalbands acid is filtered off on a tight filter with filtrowanie mass, collecting the filtrate in a beaker with a capacity of 250−300 cm
. The filter residue is washed with hot nitric acid (1:100) 5−6 times. To the filtrate add 10 cm
of nitric acid (1:1), diluted with water 100−150 cm
and the electrolysis is carried out as specified in clause 5.3.1
.
6.4. Processing of the results
6.4.1. Mass fraction of lead (a) percentage calculated by the formula
where is the mass of the anode from the separated precipitate of dioxide of lead, g;
— mass of anode, g;
0,8661 — the conversion factor of lead dioxide on a lead; — the weight of the portion,
6.4.2. The absolute discrepancies in the results of parallel measurements ( — convergence) must not exceed the permissible values given in table.1.
6.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of analysis obtained in the same laboratory but under different conditions (the reproducibility) shall not exceed the values specified in table.1.
6.4.4. The control accuracy of the analysis carried out according to State standard samples (GSO) or industry standard sample (CCA), or by standard samples of the enterprise (SOP) copper-zinc alloys, approved GOST 8.315, or by additives, or by comparing the results obtained by another method in accordance with GOST 25086.
6.4.2−6.4.4. (Changed edition, Rev. N 3).
