GOST 15027.11-77
GOST 15027.11−77 Bronze without tin. Methods for determination of phosphorus (with Amendments No. 1, 2, 3, adjusted)
GOST 15027.11−77
Group B59
INTERSTATE STANDARD
BRONZE WITHOUT TIN
Methods for determination of phosphorus
Non-tin bronze.
Methods for the determination of phosphorus
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 15027.11−69
4. The standard fully complies ST SEV 1531−79 and ST SEV 5008−85 in part photometric and extraction-photometric methods for the determination of phosphorus
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced | Section number, paragraph, sub-paragraph |
| GOST 493−79 |
Chapeau |
| GOST 614−97 |
Chapeau |
| GOST 3118−77 |
2.2, 3.2 |
| GOST 3760−79 |
2.2, 4.2 |
| GOST 3765−78 |
2.2, 3.2, 4.2 |
| GOST 3772−74 |
2.2 |
| GOST 4166−76 |
3.2, 4.2 |
| GOST 4172−76 |
2.2, 3.2 |
| GOST 4198−75 |
2.2, 4.2 |
| GOST 4204−77 |
3.2 |
| GOST 4461−77 |
2.2, 3.2, 4.2 |
| GOST 6006−78 |
3.2 |
| GOST 9336−75 |
2.2 |
| GOST 9656−75 |
2.2, 3.2 |
| GOST 10484−78 |
2.2, 3.2, 4.2 |
| GOST 10929−76 |
2.2 |
| GOST 18300−87 |
2.2, 3.2, 4.2 |
| GOST 20490−75 |
2.2 |
| GOST 20015−88 |
4.2 |
| GOST 25086−87 |
1.1, 2.4.4 |
| THAT 6−09−5393−88 |
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, April 1986, March 1988 (IUS 6−83, 7−86, 6−88)
AMENDED, published in IMS No. 6, 2007
An amendment made by the manufacturer of the database
This standard sets the photometric method for the determination of phosphorus (at a mass fraction of phosphorus from 0.001% to 1.2%), extraction-photometric method for the determination of phosphorus (at a mass fraction of phosphorus from 0.002% to 0.02%) and extraction-photometric method for the determination of phosphorus (at a mass fraction of phosphorus from 0.001% to 0.1%) in the tin bronze according to GOST and GOST 614 493.
The standard fully complies ST SEV 1531−79 and ST SEV 5008−85 in part photometric and extraction-photometric method for the determination of phosphorus in the yellow phosphorus-molybdenum heteropolyacid.
(Changed edition, Rev. N 1, 2).
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 1).
2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF PHOSPHORUS
2.1. The essence of the method
The method is based on formation of yellow phosphomolybdenum complex and the measurement of its optical density.
2.2. Apparatus, reagents and solutions
Photoelectrocolorimeter or spectrophotometer.
Hydrochloric acid according to GOST 3118, diluted 1:2.
Nitric acid according to GOST 4461, diluted 1:1 and 1:2, 2:3 and 1:5.
Boric acid according to GOST 9656, a solution of 40 g/DM.
Ammonia water according to GOST 3760.
Potassium permanganate according to GOST 20490, a solution of 10 g/DM.
The mixture of acids to dissolve; prepared as follows: 320 cmof concentrated nitric acid and 120 cm
of hydrochloric acid diluted with water to 1000 cm
.
Ammonium undeviatingly meta GOST 9336, is prepared as follows: 2.5 g of drug is dissolved in 500−700 cmof hot water in a volumetric flask with a capacity of 1 DM
, cooled to room temperature, add 20 cm
of concentrated nitric acid, made up to the mark with water, mixed and filtered.
Ammonium molybdate according to GOST 3765, recrystallized from alcoholic solution, a freshly prepared solution of 100 g/DM.
The recrystallization of ammonium molybdate is carried out as follows: 70 g of drug is dissolved in 400 cmof water when heated (70−80 °C) and double-filter the hot solution through a dense filter. To the solution was added to 250 cm
of ethyl alcohol. The solution was cooled and allowed to settle for 1 h. Precipitated crystals are filtered off on a Buchner funnel, sucking the solution and repeat the recrystallization. After the second suction, the crystals washed 2−3 times with ethanol, diluted 5:8, portions at 20−30 cm
. After this they are dried in the air.
Rectified ethyl alcohol according to GOST 18300 and diluted 5:8.
Hydrogen peroxide according to GOST 10929, 3% solution.
High purity copper with a phosphorus content of not more than 0,0002%.
Hydrofluoric acid according to GOST 10484.
Sodium phosphate disodium GOST 4172.
Potassium phosphate according to GOST odnosemjannyj 4198.
Ammonium disodium phosphate according to GOST 3772.
The standard solutions of phosphorus; prepared as follows: 0,4395 g of single phosphate or potassium 0,4586 g twosemester sodium phosphate or 0,4260 g twosemester ammonium phosphate (previously dried at 105 °C to constant weight) was placed in a volumetric flask with a capacity of 250 cm(solution A) 500 cm
(solution B) and 1000 cm
(In solution), dissolved in water, made up to the mark with water and mix.
Solution A contains 0.0004 g of phosphorus at 1 cm.
Solution B contains 0.0002 g of phosphorus at 1 cm.
The solution contains 0.0001 g of phosphorus at 1 cm.
Solution G: 25 cmsolution is placed in a volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Solution G contains 0,000025 g of phosphorus at 1 cm.
(Modified …
tion, Rev. N 2).
2.3. Analysis
2.3.1 for the mass concentration of phosphorus up to 0.1%
2.3.1.1. In the analysis of bronzes with a mass fraction of tin and silicon to 0.05%.
The sample of bronze with a weight of 2.5 g (at a mass fraction of phosphorus from 0.001% to 0.005%) and 1 g (in mass fraction of phosphorus in excess of 0.005%) were placed in a glass with a capacity of 250 cm, add 25 or 10 cm
of nitric acid 2:3 and dissolved first in cold and then when heated. Nitrogen oxides are removed by boiling. Add 1 cm
of solution of potassium permanganate, and heated nearly to boiling. Add 2 cm
of hydrogen peroxide solution, the solution was stirred until the destruction of the excess of potassium permanganate and bleaching solution. Add 5 cm
of the solution vadeevaloo ammonium and gently boil for about 1 min to decomposition of hydrogen peroxide. The solution was cooled, transferred to a volumetric flask with a capacity of 50 cm
, add 5 cm
of molybdate ammonium solution, made up to the mark with water and mix. After 5 min measure the optical density of the solution on a photoelectrocolorimeter with a blue filter or on a spectrophotometer at a wavelength of 440 nm in a cuvette length of 1 cm with a Solution of comparison is the sample solution, which is not a solution of molybdate of ammonium.
(Changed edition, Rev. N 2)
.
2.3.1.2. In the analysis of bronzes with a mass fraction of silicon in excess of 0.05%.
The sample of bronze with a weight of 1 g was placed in a platinum Cup or Teflon beaker, add 15 cmof boric acid solution, 2 cm
hydrofluoric acid, 10 cm
of concentrated nitric acid and dissolve. After dissolution, the solution kept for 1 h at 90 °C. the Solution was transferred to a glass beaker with a capacity of 100 cm
, rinsing with 5 cm
of water, add 1 cm
of solution of potassium permanganate and heated to boiling.
Add 2 cmof hydrogen peroxide solution, the solution was stirred until the destruction of the excess of potassium permanganate and bleaching solution. The solution is neutralized with ammonia to a pH of 3, add 5 cm
of nitric acid, diluted 1:1, 5 cm
solution vadeevaloo ammonium, boil for 1 minute and then do as described in claim 2.3.1
.1.
2.3.1.3. In the analysis of bronzes with a mass fraction of tin in excess of 0.05%.
The sample of bronze with a weight of 1 g was placed in a beaker with a capacity of 100 cm, add 15 cm
of the mixture of acids to dissolve and moderately heated to complete dissolution. Add 1 cm
of hydrogen peroxide and gently boil for 3−5 minutes, avoiding loud and prolonged boiling. Then add 5 cm
of the solution vadeevaloo ammonium, cooled, transferred to a volumetric flask with a capacity of 50 cm
, add 5 cm
of molybdenic acid ammonium solution and then act as described in section
2.3.1.4. Manufacturing control experience.
In a glass with a capacity of 100 cmis placed 25 or 10 cm
of nitric acid, diluted 2:3 and boil to remove oxides of nitrogen. Add 1 cm
of a solution of potassium permanganate, and then do as described in claim
2.3.1.5. Construction of calibration graphs for the analysis of bronzes, containing up to 0.05% tin and silicon
2.3.1.5.1. When the mass fraction of phosphorus from 0.001% to 0.005%
Six glasses with a capacity of 250 cmis placed 2.5 g of copper and five of them add 1,0; 2,0; 3,0; 4,0 and 5,0 cm
standard solution G of phosphorus. All the beakers add 25 cm
of a solution of nitric acid (2:3) and then do as described in claim
Solution comparison is the solution not containing phosphorus. According to the obtained values build the calibration graph.
2.3.1.5.2. When the mass fraction of phosphorus in excess of 0,005%
Ten cups with a capacity of 100 cmplaced 1 g of copper and nine of them add 0,5; 1,0; 2,0; 3,0; 4,0; 5,0; 7,5; 10,0 and 12.0 cm
standard solution In phosphorus. In all the glasses added to 10 cm
of nitric acid 2:3 and then do as described in claim
Solution comparison is the solution not containing phosphorus. According to the obtained values build the calibration graph.
2.3.1.4−2.3.1.5.2. (Changed edition, Rev. N 2).
2.3.1.6. Construction of calibration curve in the analysis of bronzes with a mass fraction of silicon in excess of 0.05%.
Eight platinum fluoroplastic cups or glasses placed in 1 g of copper and seven of them added 0,5; 1,0; 2,5; 5,0; 7,5; 10,0 and 12.0 cmstandard solution V. In all cups or glasses, add 15 cm
of boric acid solution, 2 cm
hydrofluoric acid, 10 cm
of concentrated nitric acid and then act as described in claim
2.3.1.7. Construction of calibration curve in the analysis of bronzes with a mass fraction of tin in excess of 0.05%.
In eight glasses with a capacity of 100 cmplaced 1 g of copper and seven of them added 0,5; 1,0; 2,5; 5,0; 7,5; 10,0 and 12.0 cm
standard solution V. In all the cups add 15 cm
of the mixture of acids and then do as described in claim
2.3.2. When the mass fraction of phosphorus above 0.1%.
2.3.2.1. The weight of bronze weighing 0.5 g were placed in a glass with a capacity of 100 cm, add 20 cm
of the mixture of acids and moderately heated to complete dissolution. Add 1 cm
of hydrogen peroxide solution and gently boil for 3−5 minutes, avoiding loud and prolonged boiling. Then add 10 cm
of a solution of ammonium anadalucia, cooled, transferred to a volumetric flask with a capacity of 100 cm
, add 10 cm
of molybdate ammonium solution, add water mark and mix. After 5 min measure the optical density of the solution on a photoelectrocolorimeter with a blue filter or on a spectrophotometer at a wavelength of 470 nm in a cuvette length of 1 cm with a Solution of comparison is the solution to which is not added to a solution of molybdate of ammonium.
2.3.2.2. Construction of calibration curve.
Nine of cups with a capacity of 100 cmis placed 0.5 g of copper and eight of them add 1,0; 2,0; 3,0; 5,0 and 10,0 cm
standard solution B; 8,0; 10,0 and 15,0 cm
standard solution A. all glasses are added in 20 cm
of a mixture of acids and then do as described in claim
Solution comparison is the solution not containing phosphorus.
According to the obtained results build a calibration curve.
2.4. Processing of the results
2.4.1. Mass fraction of phosphorus () in percent is calculated by the formula
where is the mass of phosphorus in the sample was found in the calibration schedule g;
— the mass of phosphorus in a control experiment, was found in the calibration schedule g;
— the weight of the portion,
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.1.
Table 1
| Mass fraction of phosphorus, % |
|
|
Mass fraction of phosphorus, % |
|
|
| From 0.001 to 0.0025 |
0,0004 | 0,001 | SV. 0.05−0.10 | 0,005 | 0,01 |
| SV. Of 0.0025 «to 0.005 |
About 0.0006 | 0,001 | «0,1» 0,2 | 0,01 | 0,02 |
| «To 0.005» 0.010 is |
0,001 | 0,002 | «0,2» 0,5 | 0,02 | 0,05 |
| «0,01» 0,02 |
0,002 | 0,005 | «0,5» 0,8 | 0,03 | 0,1 |
| «0,02» 0,05 |
0,003 | 0,007 | «0,8» 1,2 | 0,05 | 0,1 |
(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.1.
2.4.4. 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 by a method of additives in accordance with GOST 25086.
2.4.3,
3. EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF PHOSPHORUS BY THE MOLYBDOPHOSPHORIC BLUE COLOR OF HETEROALICYCLIC
3.1. The essence of the method
The method is based on the extraction of complex phosphorus with ammonium molybdate at a pH of 1.5 n-butyl alcohol, restore it with tin dichloride directly in the organic phase to the molybdophosphoric blue and measuring optical density of colored solution.
3.2. Apparatus, reagents and solutions
Photoelectrocolorimeter or spectrophotometer.
Nitric acid according to GOST 4461, diluted 1:2.
Hydrochloric acid according to GOST 3118, diluted 1:1.
Chloric acid, diluted 1:10 and 1:1.
Sulfuric acid according to GOST 4204, diluted 1:5 and a solution of 0.05 mol/DM.
Ammonium molybdate according to GOST 3765, solution; is prepared as follows: 15 g of the recrystallized ammonium molybdate is dissolved in 300 cmof sulphuric acid diluted 1:5 and filtered.
The recrystallization of ammonium molybdate in step 2.2.
Rectified ethyl alcohol according to GOST 18300 and diluted 5:8.
Tin dichloride on the other 6−09−5393, freshly prepared mortar, prepared as follows: 4 g of drug is dissolved in 100 cmof hot hydrochloric acid, diluted 1:1, 1 cm
of this solution is diluted with 50 cm
of a solution of 0.05 mol/DM
sulphuric acid.
Hydrofluoric acid according to GOST 10484.
Sodium sulphate anhydrous according to GOST 4166.
Sodium phosphate disodium GOST 4172.
Alcohol n-butyl according to GOST 6006, distilled at 118 °C.
The standard solutions of phosphorus.
Solution A, prepared as follows: dosagedosage of 2.29 g of sodium phosphate, dried at 105 °C, dissolved in water, transferred to a volumetric flask with a capacity of 1 DMwater and dilute to the mark.
1 cmof the solution contains 0.0005 g of phosphorus.
Solution B is prepared as follows: 10 cmof the solution 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 FOS
fora.
3.3. Analysis
3.3.1. For bronzes not containing silicon
The weight of bronze (PL.2) is placed in a beaker with a capacity of 250 cm, cover with a watch glass and dissolved in 20 cm
of nitric acid, diluted 1:2.
Table 2
| Mass fraction of phosphorus, % |
The mass of charge, g |
| From 0.002 to 0.005 |
1 |
| SV. 0,005 «0,01 |
0,5 |
| «0,01» 0,02 |
0,25 |
After dissolution of the sample wall of the glass beaker and washed with water. In a glass pour 20 cmof a solution of perchloric acid diluted 1:1, and evaporate to copious white fumes and the formation of wet salts and then cooled. To the residue poured in 40 cm
of water, the beaker cover watch glass, heat to dissolve the salts, and cooled. The resulting solution was transferred to a separatory funnel with a capacity of 100−150 cm
, flow 10 cm
of perchloric acid, diluted 1:10, 5 cm
of ammonium molybdate solution and mix, then add 20 cm
n-butyl alcohol, and shake vigorously 1 min. After separation of phases the aqueous layer is discarded. In a separatory funnel pour 5 cm
of a solution of tin dichloride, mixed again for 30 s and after separation of the phases and remove the aqueous layer. The extract is transferred to a dry volumetric flask with a capacity of 50 cm
, which added 0.2 g of anhydrous sodium sulphate, rinse the funnel, n-butyl alcohol, transferred into the same volumetric flask, made up to the mark n-butyl alcohol and stirred.
Optical density of the solution is measured on a photoelectrocolorimeter with a red filter at a wavelength of 600−700 nm in a cuvette with a length of 2 cm or on the spectrophotometer at a wavelength of 780 nm.
Solution comparison is the solution, the control experience
.
3.3.2. For silicon bronze
The linkage (see table.2) is placed in a platinum Cup and dissolved in a mixture of 20 cmof nitric acid, diluted 1:2, and 2 cm
hydrofluoric acid. After dissolution, the sample solution was evaporated to dryness. To the dry residue add 10 cm
of concentrated nitric acid and repeat the evaporation to dryness three more times, each time adding 10 cm
of concentrated nitric acid. Dissolve the salt by heating in 20 cm
of nitric acid, diluted 1:2, and transfer the solution into a glass with a capacity of 250 cm
. Further analysis is carried out as specified in clause
3.3.3. Construction of calibration curve
In a separating funnel with a capacity of 100−150 cmcarry 0; 1,0; 2,0; 4,0; 6,0 and 8,0 cm
standard solution B. the Solutions were diluted with water to 20 cm
, flow 10 cm
of perchloric acid, diluted 1:10, 5 cm
of molybdenic acid ammonium solution and further analysis is carried out as specified in clause
3.4. Processing of the results
3.4.1. Mass fraction of phosphorus () in percent is calculated by the formula
where is the mass of phosphorus was found in the calibration schedule g;
— the weight of the portion,
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.1.
(Changed edition, Rev. N 2, 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 (a measure of reproducibility) shall not exceed the values given in table.1.
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. EXTRACTION-PHOTOMETRIC METHOD FOR THE DETERMINATION OF PHOSPHORUS IN THE YELLOW THE MOLYBDOPHOSPHORIC HETEROPOLYACID
4.1. The essence of the method
The method is based on formation of yellow complex of phosphorus with ammonium molybdate at pH about 1.5, and extracted with a mixture of chloroform and n-butyl alcohol.
4.2. Apparatus, reagents and solutions
Photoelectrocolorimeter or spectrophotometer.
Nitric acid according to GOST 4461, diluted 1:1 and 1:2.
Hydrofluoric acid according to GOST 10484.
Crystal violet solution 10 g/DM.
Ammonia water according to GOST 3760.
Ammonium molybdate according to GOST 3765, a solution of 50 g/DM.
The recrystallization of ammonium molybdate is carried out as specified in clause 2.2.
Rectified ethyl alcohol according to GOST 18300, diluted 5:8.
Mixture for extraction; prepared as follows: mix n-butyl alcohol and chloroform 1:3.
Mixture for washing; prepared as follows: to 500 cmof water was added 120 cm
of nitric acid, diluted 1:2, 30 cm
of ammonium molybdate solution and 40 cm
n-butyl alcohol.
Sodium sulphate anhydrous according to GOST 4166.
Potassium phosphate according to GOST odnosemjannyj 4198.
The standard solutions of phosphorus.
Solution A, prepared as follows: 0,4395 g of single potassium phosphate, dried at 105 °C, dissolved in a flask with a capacity of 1 DMand topped to the mark with water.
1 cmof the solution contains 0.0001 g of phosphorus.
Solution B is prepared as follows: 10 cmof the solution And transferred to a volumetric flask with a capacity of 100 cm
and top up with water to the mark.
1 cmof solution B has the 0.00001 g of phosphorus.
Chloroform according to GOST 20015.
(Changed edition, Rev.
N 2).
4.3. Analysis
4.3.1. For bronzes not containing silicon
Depending on the phosphorus content of a sample of bronze (PL.4) is placed in a beaker with a capacity of 250 cmand dissolved in 10−25 cm
of nitric acid, diluted 1:1, when heated.
Table 4*
| Mass fraction of phosphorus, % |
The mass of charge, g |
| From 0.001 to 0.0025 |
2 |
| SV. Of 0.0025 «to 0.005 |
1 |
| «0,005» 0,01 |
0,5 |
| «0,01» 0,02 |
0,25 |
| «0,02» 0,1 |
0,1 |
___________________
* Table 3. (Deleted, Rev. N 2).
After dissolution of the sample wall of the glass and the glass is washed with water, boil the solution to remove the oxides of nitrogen and diluted with water to 75 cm. The solution is neutralized with ammonia to pH 1.5 by controlling the pH drip test with crystal violet solution or indicator paper. The solution was transferred to a separatory funnel with a capacity of 250 cm
, and dilute with water to 100 cm
. Add 6 cm
of a solution of molybdate of ammonium, allow to stand for 10 min, then add 8 cm
of n-butyl alcohol and stirred vigorously to saturate the aqueous solution with alcohol, add 10 cm
of nitric acid, diluted 1:2 and stirred. The yellow complex of the molybdophosphoric acid and extracted with a 10 cm
mixture for extraction, gently shaken 1 min. After phase separation, the lower organic phase was transferred to another separatory funnel. To the aqueous phase is again added to the mixture for extraction, holding her still twice with 5 cm
of the mixture. The last portion of the extract should be colorless. The organic layer is washed in a separating funnel 50 cm
mixture for washing, stirring 30 s. After the partition phase the lower layer is drained into a dry volumetric flask with a capacity of 25 cm
, which is 0.2 g anhydrous sodium sulfate, stirred, and topped to the mark with the mixture for extraction.
The optical density of the extract is measured on a photoelectrocolorimeter with a purple or blue color filter at a wavelength of 420−430 nm in a cuvette with a length of 2 cm or on the spectrophotometer at a =420 nm in a cuvette length of 1 cm relative to the solution in the reference experiment.
(Changed edition, Rev.
N 2).
4.3.2. For silicon bronze
The sample (tab.4) is placed in a platinum Cup and dissolved in a mixture of 15 cmof nitric acid, diluted 1:1, and 2−3 cm
hydrofluoric acid with gentle heating and evaporated to dryness. Rinse the walls of the Cup 10 cm
of concentrated nitric acid and repeat the evaporation to dryness three more times, each time adding 10 cm
of concentrated nitric acid.
To the dry residue add 10 cmof nitric acid, diluted 1:1, dissolved salts, and the solution transferred to a beaker with a capacity of 250 cm
, rinsing the Cup with water several times and the solution was boiled to remove oxides of nitrogen, then diluted with water to 75 cm
and further analysis is carried out as specified in clause 4.3.1
.
4.3.3. Construction of calibration curve
Ten cups with a capacity of 250 cmis administered consistently 0; 1,0; 2,0; 3,0; 4,0; 5,0; 6,0; 8,0; 10,0 and 12.0 cm
of a solution of phosphorus added to 10 cm
of nitric acid, diluted 1:1, add water up to 75 cm
and then do as specified in clause
The found values of optical densities and corresponding contents of phosphorus build a calibration curve.
(Changed edition, Rev. N 2).
4.4. Processing of the results
4.4.1. Mass fraction of phosphorus () in percent is calculated by the formula
where is the mass of phosphorus was found in the calibration schedule g;
the weight of bronze,
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.1.
(Changed edition, Rev. N 2, 3).
4.4.3. The absolute discrepancies of the analysis results obtained in two different laboratories or two of the results of the analysis conducted in the same laboratory but under different conditions (a measure of reproducibility) shall not exceed the values given in table.1.
4.4.4. Control of accuracy of analysis results
Control of accuracy of analysis results is carried out according to claim
4.4.3,
