ГОСТ 15027.8-77
GOST 15027.8−77 Bronze without tin. Methods for determination of arsenic (with Amendments No. 1, 2, 3)
GOST 15027.8−77
Group B59
INTERSTATE STANDARD
BRONZE WITHOUT TIN
Methods for determination of arsenic
Non-tin bronze.
Methods for the determination of arsenic
AXTU 1709
Date of introduction 1979−01−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from
3. REPLACE GOST 15027.8−69
4. The standard fully complies ST SEV 1541−89
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Section number, paragraph |
| GOST 493−79 |
Chapeau |
| GOST 614−97 |
Chapeau |
| GOST 859−2001 |
2.2, 3.2 |
| GOST 3118−77 |
2.2, 3.2, 4 |
| GOST 3760−79 |
2.2, 3.2, 4 |
| GOST 3765−78 |
2.2, 3.2 |
| GOST 4160−74 |
2.2 |
| GOST 4204−77 |
2.2, 3.2 |
| GOST 4232−74 |
3.2 |
| GOST 4328−77 |
2.2, 3.2, 4 |
| GOST 4461−77 |
2.2, 3.2, 4 |
| GOST 5841−74 |
2.2, 3.2 |
| GOST 6563−75 |
3.2 |
| GOST 10484−78 |
2.2, 3.2, 4 |
| GOST 10929−76 |
2.2, 4 |
| GOST 14204−69 |
2.2 |
| GOST 18175−78 |
Chapeau |
| GOST 18300−87 |
2.2, 3.2 |
| GOST 20288−74 |
3.2 |
| GOST 20490−75 |
3.2 |
| GOST 25086−87 |
1.1, 4 |
| THAT 6−09−5359−87 |
3.2 |
6. Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)
7. EDITION with Amendments No. 1, 2, 3 approved in February 1983, March 1988, December 1990 (IUS 6−83, 6−88, 3−91)
This standard sets the photometric method for the determination of arsenic with pre-Stripping it, extraction-photometric method for the determination of arsenic (in mass fraction of arsenic from 0.001% to 0.4%) and nitrogen absorption method for the determination of arsenic (if arsenic mass fraction of from 0.005% to 0.4%) in the tin bronze according to GOST 18175, GOST and GOST 614 493.
(Changed edition, Rev. N 2, 3).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 25086 with the addition of sec. 1 GOST 15027.1.
(Changed edition, Rev. N 2).
2. PHOTOMETRIC METHOD WITH PRE-STRIPPING OF ARSENIC
2.1. The essence of the method
The method is based on the release of arsenic ammonia on an iron manifold, distillation of the arsenic chloride and subsequent photometric determination of arsenic in arsenic-molybdenum blue at a wavelength of 750 or 660 nm.
(Changed edition, Rev. N 1).
2.2. Apparatus, reagents and solutions
Photoelectrocolorimeter or spectrophotometer.
Apparatus for distillation of arsenic GOST 14204.
Hydrochloric acid according to GOST 3118 and diluted 1:3.
Nitric acid according to GOST 4461 and diluted 1:1.
Sulfuric acid according to GOST 4204, diluted 1:1, 1:5 and a solution of 3 mol/DM.
Hydrofluoric acid according to GOST 10484.
Peroxide (peroxide) of hydrogen according to GOST 10929, 30% solution.
Hydrazine sulfate according to GOST 5841 and a solution of 1 g/DM.
Potassium bromide according to GOST 4160.
Ammonium molybdate according to GOST 3765, recrystallized from ethyl alcohol, a solution of 10 g/DMin the solution 3 mol/DM
sulfuric acid.
The recrystallization is produced in the following manner: 70 g of salt are dissolved in 400 cmof hot water and twice filtered through a dense filter. To the solution was added to 250 cm.
of ethanol and after standing for 1 h the precipitated crystals are sucked off on a Buchner funnel, washed the resulting crystals are again dissolved in 400 cm
of water and repeat the recrystallization. After the second suction, the crystals washed several times with mixture of alcohol and water (5:8) and dried in air.
The reaction mixture, freshly prepared:
50 cmof molybdate ammonium solution diluted with water to 150 cm
, add 50 cm
of hydrazine sulfate solution and add water to 500 cm
.
Sodium hydroxide (hydroxide) according to GOST 4328, solution 100 g/DM.
Arsenious anhydride.
Phenolphthalein, solution at 10 g/lin ethanol.
Rectified ethyl alcohol according to GOST 18300 and diluted 5:8.
The dry mixture of hydrazine sulphate and potassium bromide in the ratio 1:1.
Solutions of arsenic.
Solution A, prepared as follows: 0,1320 g of arsenious anhydride is dissolved by heating in 10 cmof sodium hydroxide solution, transfer the solution into a volumetric flask with a capacity of 500 cm
, neutralized to phenolphthalein with hydrochloric acid diluted 1:3, made up to the mark with water and mix.
1 cmof the solution contains 0.0002 g of arsenic.
Solution B is prepared as follows: 25 cmsolution And transferred to a volumetric flask with a capacity of 500 cm
, made up to the mark with water and mix.
1 cmof solution B contains 0,00001 g of arsenic.
Copper of brand of M00 according to the GOST 859.
Ammonia water according to GOST 3760 and diluted 1:20.
A mixture of acid, freshly prepared; prepared as follows: three volumes of hydrochloric acid mixed with one volume of nitric acid.
Iron, the reduced hydrogen.
Iron chloride, solution; is prepared as follows: 0.75 g of iron dissolved in 20 cmof concentrated hydrochloric acid with addition of hydrogen peroxide. The solution was transferred to a volumetric flask with a capacity of 250 cm
, made up to the mark with water and mix.
(Amended
, Edit. N 1, 3).
2.3. Analysis
2.3.1. For all bronzes except bronze brand PCMC 3−1
The weight of bronze weighing 0.2 g was placed in a beaker with a capacity of 600 cmand dissolved without heating in 10 cm
of a mixture of acids. The solution is diluted with water to a volume of 100 cm
, add 10 cm
of a solution of ferric chloride, heated to 70 °C and ammonia is added to complete the transition of copper ammonium complex. After 30 min the precipitate was filtered off on a medium density filter and washed several times with ammonia diluted 1:20, then warm water. The precipitate of hydroxides was dissolved in 25 cm
of sulphuric acid, diluted 1:4 in the glass in which was conducted the deposition, and the filter was washed 5−7 times in hot water.
The solution is evaporated until white smoke of sulfuric acid, cooled, rinse walls of beaker with water and again repeat the evaporation to white fumes.
The residue is cooled, wash the walls of the beaker with water and dissolve the residue in a small volume of water (about 20 cm), the solution was transferred to distillation flask of the device containing 1 g of dry mixture of hydrazine, potassium bromide, and connect the flask with a refrigerator.
Poured into a flask of 50 cmof concentrated hydrochloric acid and distilled arsenic in the form of trichloride, driving 2/3 of the original volume, with a uniform boiling (for uniform boiling in a flask placed glass beads). The distillate collected in the flask-receiver with a capacity of 250 cm
, containing 25−30 cm
of water. In order to avoid partial volatilization of the arsenic attached to the control receiver with 10−15 cm
of water. To both flasks add 1−2 drops of hydrogen peroxide. The distillate and the liquid control receiver combined, pour 10 cm
of concentrated nitric acid and evaporate the solution to dryness, avoiding heating the residue above 130 °C. the Glass with a dry residue kept in a desiccator for 1 h at 120−130 °C. After cooling, the dry residue moistened with 1−2 drops of sodium hydroxide solution, poured 20 cm
of water and boil for 3−5 min. the Cooled solution is neutralized with sulfuric acid, diluted 1:5, before the transition of the red color indicator paper Congo blue and pour 3−5 drops of sulfuric acid. Then translate the solution into a volumetric flask with a capacity of 100 cm
(for the mass concentration of arsenic up to 0.025% is used, the whole solution).
The solution in the volumetric flask made up to mark with distilled water and mix.
Aliquot part of the solution (table.1) or the entire solution is placed in a volumetric flask with a capacity of 50 cm35 cm is added
the reaction mixture and heated in a water bath for 10−15 min to develop the color.
Table 1
| Mass fraction of arsenic, % | The volume aliquote part of the solution, cm |
The weight of the portion corresponding to the taken aliquote part g |
| To 0.025 |
The entire solution | 0,2 |
| SV. Of 0.025 «to 0.05 |
20 | 0,04 |
| «To 0.05» to 0.20 |
10 | 0,02 |
| «Of 0.20» to 0.40 |
5 | 0,01 |
Colored solution was cooled, poured the reaction mixture to the mark, mix and measure its optical density on a photoelectrocolorimeter with a red filter at a wavelength of 600 and 750 nm in a cuvette with a length of 5 cm or a spectrophotometer with a cuvette length of 1 cm as a solution of comparison using the solution in the reference experiment.
The levels of arsenic found by the calibration schedule.
(Changed edition, Rev. N 1, 3).
2.3.2. For bronzes brands PCMC 3−1
A sample weighing 1 g is placed in a platinum Cup, poured 20 cmof nitric acid, diluted 1:1, 2 cm
hydrofluoric acid and heated to dissolve sample. The solution was evaporated almost to dryness. Then pour 10 cm
of sulphuric acid diluted 1:1, evaporated to a thick white smoke of sulfuric acid. The residue is cooled, dissolved in 50 cm
of water and a small amount of hydrochloric acid, diluted 1:2, the solution was transferred to a beaker with a capacity of 600 cm
and continue with the analysis as described in section
(Changed edition, Rev. N 1).
2.3.3. Construction of calibration curve
In glasses with a capacity of 100 cmis placed 0.2 g of copper, pour standard solution B in an amount of 0; 1,0; 2,0; 3,0; 4,0 and 5,0 cm
, flow 10 cm
of nitric acid, diluted 1:1 and dissolved by heating. After dissolution the sample is injected at the 10 cm
of sulphuric acid diluted 1:1 and poured to release white smoke of sulfuric acid. Further analysis are as indicated in claim
Note. When construction of calibration curve analysis of bronze stamps PCMC 3−1, specified in item 2.3.2, is carried out in a platinum Cup and introduce 1 g of copper.
Solution comparison is the solution not containing arsenic.
2.4. Processing of the results
2.4.1. Mass fraction of arsenic () in percent is calculated by the formula
where is the mass of arsenic, was found in the calibration schedule g;
— the weight of the portion corresponding to aliquote part of the solution,
2.4.2. The absolute discrepancies in the results of parallel measurements (the rate of convergence) must not exceed the permissible values given in table.2.
Table 2
| Mass fraction of arsenic, % |
|
|
| To 0.005 |
0,001 | 0,001 |
| SV. 0,005 «0,01 |
0,0015 | 0,002 |
| «0,01» 0,02 |
0,004 | 0,006 |
| «0,02» 0,05 |
0,007 | 0,01 |
| «To 0.05» to 0.15 |
0,01 | 0,01 |
| «To 0.15» to 0.40 |
0,02 | 0,03 |
(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 (a measure of reproducibility) shall not exceed the values given in table.2.
2.4.4. Control of accuracy of analysis results
Control of accuracy of analysis results is carried out by additives or by State standard samples without tin bronzes, certified in the prescribed manner in accordance with GOST 25086.
2.4.3,
3. EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF ARSENIC
3.1. The essence of the method
The method is based on formation of yellow arsenic-molybdenum complex followed by reduction of its sulfate with hydrazine in acidic solution to arsenic-molybdenum blue and the measurement of the optical density of colored solution.
Arsenic from the basic components of the alloys are pre-separated by coprecipitation with iron hydroxide and subsequent extraction in the form of iodide of arsenic (III) carbon tetrachloride and Stripping it with water.
3.2 Equipment, reagents and solutions
Installation for electrolysis with platinum electrodes according to GOST 6563.
Photoelectrocolorimeter or spectrophotometer.
Nitric acid according to GOST 4461 and diluted 1:1.
Sulfuric acid according to GOST 4204, diluted 1:1, 1:4 and 6 mol/DMsolution.
Hydrofluoric acid according to GOST 10484.
Hydrochloric acid according to GOST 3118 and diluted 1:3.
Ammonia water according to GOST 3760 and diluted 1:50.
Sodium hydroxide (hydroxide) according to GOST 4328, solution 100 g/DM.
Ammonium molybdate according to GOST 3765, recrystallized from alcohol solution, a solution of 10 g/DMin the solution is 6 mol/DM
sulfuric acid (recrystallization of ammonium molybdate in clause 2.2).
Potassium iodide according to GOST 4232, a solution of 0.12 mol/DMin concentrated hydrochloric acid; prepared as follows: 10 g of potassium iodide dissolved in 500 cm
of concentrated hydrochloric acid. The solution is prepared the day of application.
Hydrazine sulfate according to GOST 5841, a solution of 1.5 g/DM.
Hydrazine-molybdate solution; prepared as follows: to 50 cmof a solution of ammonium molybdate add 5 cm
of hydrazine sulfate and dilute with water to 100 cm
. Use freshly prepared solution.
Alum salesonline on the other 6−09−5359, solution 100 g/l; prepared as follows: 10 g of alum was dissolved with heating in 70 cm
water and 5 cm
of concentrated nitric acid, the solution filtered and diluted with water to 100 cm
.
Potassium permanganate according to GOST 20490, a solution of 1 g/DM.
Carbon tetrachloride according to GOST 20288.
Phenolphthalein, solution at 10 g/lin ethanol.
Rectified ethyl alcohol according to GOST 18300.
Copper of brand of M00 according to the GOST 859.
Standard solutions of arsenic (see preparation
in p.2.2).
3.3. Analysis
3.3.1. For all bronzes except the bronze brands PCMC 3−1 and Brs30
The weight of bronze weighing 0.2 g was placed in a beaker with a capacity of 250 cm, add 1 cm
of a solution of alum salesonline (if the iron is not one of the components of bronze), 10 cm
of nitric acid, diluted 1:1, covered with a glass watch glass and dissolved under heating. The solution was cooled, washed with a watch glass and walls of glass with water and diluted with water to a volume of 150 cm
. To the obtained solution was added a solution of ammonia to form a dark blue ammonia complex of copper solution and kept for 30 min at 50−60 °C for coagulation of the precipitate of iron hydroxide. The precipitate was filtered off on a medium density filter and washed 6−8 times with a solution of ammonia, diluted 1:50. The filter cake is dissolved in 20−25 cm
hot sulphuric acid, diluted 1:4 in the glass in which was conducted the deposition, and the filter was washed 5−7 times in hot water.
The solution was evaporated until a white smoke of sulfuric acid, washed the walls of the beaker with water and repeat the evaporation until a white smoke of sulfuric acid, rinse the glass wall of 5−10 cmof water added to a glass of 0.2−0.3 g of hydrazine sulfate and heated 5−10 min. the Solutions were cooled.
When the mass fraction of arsenic in bronze up to 0.025% for the analysis using the full solution with the mass fraction of arsenic from 0.025% and the above solution is transferred to a volumetric flask with a capacity of 25 cm, top up to the mark with water, mixed and taken for analysis aliquot part 5 cm
(when the mass fraction of arsenic from 0.025% to 0.1%), 2.5 cm
(from 0.1% to 0.2%) and 1 cm
(from 0.2% to 0.4%).
The entire solution or aliquot part is placed in a separating funnel with a capacity of 250 cm, the walls of the glass should be rinsed with 5 cm
of water. If they use not the whole solution, and aliquot part, then add 20 cm
of sulphuric acid, diluted 1:4. Add 60 cm
of a solution of potassium iodide, 30 cm
of carbon tetrachloride and extracted arsenic for 2 min. the Organic layer drained into another separatory funnel with a capacity of 100−150 cm
, and in the first add 15 cm
of carbon tetrachloride and repeat the extraction again. The extracts are washed for 2 minutes with 20 cm
solution, which is prepared by combining three parts of a solution of potassium iodide and one part water. The washed organic layer is drained into a third separatory funnel with a capacity of 100−150 cm
, flow 15 cm
of water and carry out the Stripping of arsenic by shaking for 2 min. the Organic layer is poured into the fourth separating funnel with a capacity of 100−150 cm
and repeat the Stripping under the same conditions. Water layers merge into a measuring flask with a capacity of 50 cm
, is added dropwise a solution of potassium permanganate until pink colour, which is then eliminated by adding dropwise a solution of hydrazine sulfate. To the resulting solution was added to 4 cm
of freshly prepared hydrazine-molybdates of the solution and the flask with reaction mixture was placed in a boiling water bath. In 10−15 min the solution was cooled, made up to the mark with water, mix and measure optical density on a photoelectrocolorimeter with a red light filter (
=656−700 nm) in a cuvette with a length of 5 cm or a spectrophotometer with a cuvette length of 1 cm at a wavelength of 840 nm. Solution comparison is the solution of the control experiment through all stages of the analysis.
(Modified re
Doccia, Rev. N 2).
3.3.2. For bronze stamps PCMC 3−1
The sample of bronze with a weight of 1 g was placed in a platinum Cup and dissolved in 10 cmof nitric acid, diluted 1:1, and 2 cm
hydrofluoric acid. After dilution pour 10 cm
of sulphuric acid diluted 1:1, and evaporated to release white smoke of sulfuric acid. After cooling, dissolve the salt in a little water and the solution transferred to a beaker with a capacity of 250 cm
. Add 1 cm
of solution gentoomaniac alum, dilute with water to 150 cm
and continue with the analysis as described in section 3.3.1, using for the analysis of the whole solution.
3.3.3. For bronze stamps Brs30
The weight of bronze weighing 0.5 g is dissolved in 15 cm.of nitric acid diluted 1:1, when heated in glass with a capacity of 250 cm
. After dissolve and remove oxides of nitrogen by boiling and transferred the solution into a volumetric flask with a capacity of 100 cm
, washing the glass with water. The solution in the flask was diluted to the mark with water and mix, selected aliquot part of the solution was 10 cm
(or 5 cm
if the mass fraction of arsenic above 0.1%) in a beaker with a capacity of 250 cm
, add 10 cm
boiled nitric acid, diluted 1:1, add water to a volume of about 100 cm
and provided the bulk of copper and lead by electrolysis for 30 min. At the end of the electrolysis is washed with electrodes of probyvali a small amount of water to the same glass, pour 1 cm
of solution gentoomaniac alum and ammonia, continuing the analysis, as indicated in paragraph 3.3
.1.
3.3.4. Construction of calibration curve
Six glasses with a capacity of 250 cmis placed 0.2 g of copper (in the analysis of bronze stamps PCMC 3−1 1 g), add 1 cm
of solution gentoomaniac alum and administered consistently 0; 1,0; 2,0; 3.0, 4.0 and 5.0 cm
standard solution B. To each beaker was added 10 cm
of nitric acid, diluted 1:1, and further analysis are as indicated in claim
The found values of optical densities build the calibration graph.
3.4. Processing of the results
3.4.1. Mass fraction of arsenic () in percent is calculated by the formula
where is the mass of arsenic, was found in the calibration schedule g;
— the weight of the portion corresponding to aliquote part of the solution,
3.4.2. The absolute discrepancies in the results of parallel measurements (the rate of convergence) must not exceed the permissible values given in table.2.
(Changed edition, Rev. N 2).
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 (a measure of reproducibility) shall not exceed the values given in table.2.
3.4.4. Control of accuracy of analysis results
Control of accuracy of analysis results is carried out according to claim
3.4.3,
4. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF ARSENIC
4.1. The essence of the method
The method is based on dissolving the samples in acids, separation of arsenic by coprecipitation with ferric hydroxide, dissolving the precipitate in hydrochloric acid and measuring the atomic absorption of arsenic in the flame acetylene-air or acetylene-nitrous oxide at a wavelength of 193.7 nm.
4.2. Apparatus, reagents and solutions
Atomic absorption spectrometer with a radiation source for arsenic.
Nitric acid according to GOST 4461 and diluted 1:1.
Hydrochloric acid according to GOST 3118 and diluted 1:1 and 1:5.
A mixture of acid: mix one volume of nitric acid with three volumes of hydrochloric acid.
Hydrofluoric acid according to GOST 10484.
Sulfuric acid according to GOST 4204, diluted 1:1.
Ammonia water according to GOST 3760 and diluted 1:99.
Hydrogen peroxide (peroxide) according to GOST 10929.
Sodium hydroxide (hydroxide) according to GOST 4328, solution 80 g/l, freshly prepared.
Iron, the reduced hydrogen.
Iron chloride, solution: 0.75 g of iron dissolved in 20 cmof hydrochloric acid with addition of hydrogen peroxide solution, the solution transferred to a volumetric flask with a capacity of 250 cm
, and topped to the mark with water.
1 cmof the solution contains 0.003 g of iron.
Arsenic oxide.
Standard solution of arsenic: 1.3200 levels g of the oxide of arsenic dissolved in 20 cmof sodium hydroxide solution, add 10 cm
water, 10 cm
of hydrochloric acid solution (1:5), transferred to a volumetric flask with a capacity of 1 DM
and topped to the mark with water.
1 cmof the solution contains 0.001 g mouse
ka.
4.3. Analysis
4.3.1. For alloys containing silicon, not more than 0.05%
A sample of alloy weighing 5 g were placed in a glass with a capacity of 400 cmand dissolved by heating at 40 cm
of a mixture of acids. The solution is diluted with water to a volume of 200 cm
, add 10 cm
of a solution of ferric chloride, heated to 70 °C, and carefully neutralized with ammonia before formation of a soluble ammonia complex of copper and add another 5 cm
in excess. The solution was heated and leave in a warm place for 30 minutes, then filtered through a filter of medium density. The filter cake is washed three times with hot ammonia solution (1:99), then twice with hot water. The precipitate is dissolved in 10 cm
of hot hydrochloric acid (1:1), collecting the solution in a glass, which conducted the deposition. The solution was transferred to a volumetric flask with a capacity of 25 cm
and top up with water to the mark. At the same time spend control experience.
Depending on the mass fraction of arsenic taken aliquot part of the solution and placed in a volumetric flask (see table 3), made up to the mark with hydrochloric acid (1:5).
Table 3
| Mass fraction of arsenic, % | The volume aliquote part of the solution, cm |
Capacity volumetric flasks, cm |
| From 0.005 to 0.05 |
The entire solution | - |
| SV. Of 0.05 «to 0.25 |
5 | 25 |
| «And 0.25» to 0.4 |
5 | 50 |
Measure the atomic absorption of arsenic in the flame acetylene-air or acetylene-nitrous oxide at a wavelength of 193.7 nm parallel to the calibration solutions.
4.3.2. For alloys containing silicon in excess of 0.05%
A portion of the sample weighing 5 g was placed in a platinum Cup and dissolved by heating in 30 cmof nitric acid (1:1) and 5 cm
hydrofluoric acid. Then add 10 cm
sulphuric acid (1:1) and evaporated until a white smoke of sulfuric acid. The Cup is cooled, add 50 cm
of water and heated to dissolve the salts. The solution was transferred to a beaker with a capacity of 400 cm
, add 10 cm
of a solution of ferric chloride and then act as described in section
4.3.3. Construction of calibration curve
In six of the seven volumetric flasks with a capacity of 100 cmis placed 0,5; 1,0; 2,5; 5,0; 7,5 and 10,0 cm
standard solution of arsenic, which corresponds to 0,5; 1,0; 2,5; 5,0; 7,5 and 10,0 mg of arsenic, made up to the mark with hydrochloric acid (1:5). Measure the atomic absorption of arsenic, as specified in clause
4.4. Processing of the results
4.4.1. Mass fraction of arsenic () in percent is calculated by the formula
where is the concentration of arsenic in the analyzed solution alloy, was found in the calibration schedule, g/cm
;
— the concentration of arsenic in solution in the reference experiment, was found in the calibration schedule, g/cm
;
— the dilution factor;
— the volume of the sample solution, cm
;
— the weight of the portion of the sample,
G.
4.4.2. The absolute discrepancies in the results of parallel measurements (the rate of convergence) must not exceed the permissible values given in table.2.
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 (a measure of reproducibility) shall not exceed the values given in table.2.
4.4.4. Control of accuracy of analysis results
Control of accuracy of analysis results is carried out according to state standard samples without tin bronzes, certified in the prescribed manner, or method of additions or by comparison of the results obtained photometric methods in accordance with GOST 25086.
Sec. 4. (Added, Rev. N 3).
