GOST 15027.2-77
GOST 15027.2−77 Bronze without tin. Methods for determination of aluminium (with Amendments No. 1, 2)
GOST 15027.2−77
Group B59
INTERSTATE STANDARD
BRONZE WITHOUT TIN
Methods for determination of aluminium
Non-tin bronze.
Method for the determination of aluminium
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 15027.2−69
4. The standard fully complies ST SEV 1532−79
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Section number, paragraph |
| GOST 61−75 |
2.2, 3.2, 3A.2, 4.2, 5.2 |
| GOST 199−78 |
3.2, 3b.2, 4.2, 5.2 |
| GOST 435−77 |
2.2 |
| GOST 493−79 |
Chapeau |
| GOST 614−97 |
Chapeau |
| GOST 859−2001 |
2.2, 3.2, 3b.2 |
| GOST 2062−77 |
4.2, 5.2 |
| GOST 3117−78 |
2.2, 3.2, 3A.2, 4.2, 5.2 |
| GOST 3118−77 |
2.2, 3.2, 3A.2, 3b.2, 4.2, 6.2, 7.2 |
| GOST 3760−79 |
2.2, 3A.2, 4.2, 5.2 |
| GOST 3773−72 |
4.2, 5.2 |
| GOST 4109−79 |
4.2, 6.2 |
| GOST 4204−77 |
3.2, 3A.2, 3b.2, 4.2, 5.2 |
| GOST 4206−75 |
5.2 |
| GOST 4233−77 |
3.2, 3A.2, 6.2 |
| GOST 4328−77 |
4.2 |
| GOST 4461−77 |
2.2, 3.2, 3A.2, 3b.2, 4.2, 5.2, 6.2, 7.2 |
| GOST 4463−76 |
2.2, 3.2 |
| GOST 4518−75 |
2.2, 3.2, 3A.2, 3b.2 |
| GOST 4529−78 |
3A.2 |
| GOST 4658−73 |
5.2 |
| GOST 6563−75 |
3b.2, 4.2, 5.2 |
| GOST 6691−77 |
2.2, 4.2 |
| GOST 10484−78 |
4.2 |
| GOST 10652−73 |
2.2, 3.2, 3A.2, 3b.2 |
| GOST 10929−76 |
3.2, 6.2, 7.2 |
| GOST 11069−74 |
2.2, 3.2, 3A.2, 4.2, 6.2, 7.2 |
| GOST 15027.1−77 |
4.3.1, 4.3.2, 5.3, 6.3.1, 6.3.2 |
| GOST 18175−78 |
Chapeau |
| GOST 18300−87 |
2.2, 3.2, 3b.2, 5.2 |
| GOST 20478−75 |
5.2 |
| GOST 23932−90 |
5.2 |
| GOST 25086−87 |
1.1, 2.4.4, 4.4.4, |
| THAT 6−09−5077−87 |
6.2, 7.2 |
| THAT 6−09−53−59−87 |
4.2 |
| THAT 6−09−5413−88 |
4.2 |
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 approved in February 1983, March 1988 (IUS 6−83, 6−88)
This standard establishes titrimetric methods for the determination of aluminium with a visual or amperometric indication of the endpoint of the titration, with the separation of aluminium from interfering elements at a mercury cathode and with the separation of aluminum from copper electrolysis with platinum electrodes (at a mass fraction of aluminum from 3.0% to 13%), a photometric method for the determination of aluminum (with a mass fraction of aluminum from 0.005% to 0.25%), a gravimetric method for the determination of aluminum (with a mass fraction of aluminum from 3% to 13%) and atomic absorption method for the determination of aluminum (with a mass fraction of aluminum from 0.01 to 0.25% and from 3% to 13%) in tin bronze according to GOST 18175, GOST and GOST 614 493.
(Changed edition, Rev. N 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 2).
2. TITRIMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM WITH A VISUAL INDICATION OF THE TITRATION END POINT
2.1. The essence of the method
The method is based on the introduction of the sample solution and excess solution of Trilon B, which forms complexes with all components of the alloy, the titration of excess in the presence of the indicator 1-(2-pyridylazo)-2-naphthol, the decomposition of complexonate of aluminium by adding ammonium fluoride or sodium and the titration of Trilon B emitted in a quantity equivalent to the aluminium content.
2.2. Apparatus, reagents and solutions
Nitric acid according to GOST 4461, diluted 1:1.
Hydrochloric acid according to GOST 3118, diluted 1:1.
Ammonia according to GOST 3760, diluted 1:1.
Acetic acid according to GOST 61.
Ammonium acetate according to GOST 3117, a solution of 200 g/DM.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652.
1-(2-Pyridylazo)-2 naphthol (PAN), ethanolic solution of 1 g/DM.
Rectified ethyl alcohol according to GOST 18300.
Sodium fluoride according to GOST 4463.
Ammonium fluoride according to GOST 4518, solution 100 g/DM.
Urea according to GOST 6691, a solution of 100 g/DM.
Copper according to GOST 859, stamps M0 and M00.
Standard copper solution, 0.05 mol/l; prepared as follows: 3,177 g of copper is dissolved in 30 cm
of nitric acid, diluted 1:1. Once dissolved, boil the solution to remove the oxides of nitrogen, cooled, neutralized with ammonia before the advent of the stable precipitate, which is dissolved by adding acetic acid, and diluted to 1 DM
.
Aluminum brand А999 according to GOST 11069.
A standard solution of aluminum prepared by dissolving 1 g of aluminum 10 cmof hydrochloric acid diluted 1:1, transferred to a volumetric flask with a capacity of 1 DM
and up to the mark and top up with water.
1 cmof the solution contains 0.001 g of aluminium.
Determination of the titer of a solution of copper
Take 20 cmof a standard solution of aluminum in a conical flask with a capacity of 500 cm
, is diluted with water up to 50−60 cm
, neutralized with ammonia before formation of a stable precipitate, which is dissolved by adding hydrochloric acid and over this pour two drops in excess. Add 20 cm
of the solution Trilon B, 100−250 cm
of hot water and heated to boiling. In the hot solution is poured 10 cm
of a solution of ammonium acetate, 0.5 cm
of the solution PAN and the hot solution titrated with standard copper solution until the transition of the green color of the solution blue, then add 1 g of sodium fluoride (or ammonium), boiled for 5 min and again titrate with the copper solution until the transition of the green color of the solution blue.
The titer of the solution (), expressed in grams of aluminium per 1 cm
of a solution, calculated by the formula
where is the mass of aluminium, suitable aliquote part, taken for titration, g;
— the volume of copper solution consumed in the second titration, sm
.
2.3. Analysis
A sample of alloy weighing 0.5 g (for the mass concentration of aluminum of up to 5%) and 0.25 g (when the mass fraction of aluminum, more than 5%) is dissolved by heating in a conical flask with a capacity of 500 cmto 20 cm
of nitric acid, add 50−60 cm
of water and boil to remove oxides of nitrogen, then cooled, added to 10 cm
of urea solution and neutralize the solution with ammonia until the formation of a stable precipitate, which is then dissolved by adding hydrochloric acid, and over this pour two drops of hydrochloric acid in excess and further analysis are as mentioned in paragraph 2.2 when determining the titer of a solution of copper.
2.4. Processing of the results
2.4.1. Mass fraction of aluminium () in percent is calculated by the formula
where is the volume of copper solution consumed in the second titration, cm
;
the titer of the solution of copper, expressed in grams of aluminium per 1 cm
of solution;
— the weight of the portion of alloy,
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 aluminum, % |
|
|
| From 0.005 to 0.01 |
0,002 | 0,005 |
| SV. Is 0.01 «to 0.03 |
0,003 | 0,007 |
| «To 0.03» to 0.05 |
0,005 | 0,012 |
| «0,05» 0,10 |
0,008 | 0,02 |
| «To 0.10» to 0.15 |
0,010 | 0,02 |
| «0,15» 0,25 |
0,015 | 0,04 |
| From 3.0 to 5.0 |
0,07 | 0,2 |
| SV. A 5.0 «to 7.0 |
0,10 | 0,2 |
| «To 7.0» to 9.0 |
0,12 | 0,3 |
| «To 9.0» 11,0 |
0,15 | 0,4 |
| «Is 11.0» to 13.0 |
0,20 | 0,5 |
___________________
* Table.2. (Deleted, Rev. N 1).
(Changed edition, Rev. N 2).
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 comparing the results of analysis obtained with titrimetric and gravimetric or atomic absorption methods in accordance with GOST 25086.
2.4.3,
3. TITRIMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM WITH AMPEROMETRIC INDICATION OF THE ENDPOINT OF THE TITRATION
3.1. The essence of the method
The method is based on the introduction of the sample solution and excess Trilon B solution that forms complex with all the components of the alloy, the titration of an excess of solution of nitrate of copper, the decomposition of complexonate of aluminium by adding ammonium fluoride or sodium and the titration of Trilon B emitted in a quantity equivalent to the aluminium content.
3.2. Apparatus, reagents and solutions
pH-meter complete with all accessories type LPU-01 or pH-340.
Potentiometer-type of LSM-60 with a scale interval of 5 mV.
Microammeter M-95 (scale to 25 µa).
Battery voltage 2 V or dry battery of the same voltage.
Variable resistor with power of 1 mW.
Two platinum electrode, made of wire with diameter 0,8−1 mm, sealed in a glass tube. Length of the working part of the electrode 30−35 mm.
Magnetic stirrer.
Burette with a capacity of 25 cmwith Moncoutant spout.
Microburette with a capacity of 1 cmis drawn with a spout.
Nitric acid according to GOST 4461 and diluted 1:1.
Hydrochloric acid according to GOST 3118 and diluted 1:1 and 1:5.
The mixture to dissolve; preparing by mixing three volumes of concentrated hydrochloric acid with one volume of concentrated nitric acid.
Hydrochloric acid according to GOST 4204.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652, 0.2 mol/DMis prepared as follows: 74,4 Trilon B dissolved in 1 DM
of water.
Methenamine (hexamethylenetetramine).
Copper of mark M0 GOST 859.
A standard solution of copper; prepared by dissolving 3,177 g of copper to 20 cmof nitric acid, diluted 1:1, and diluting the resulting solution to 1 DM
with water in a volumetric flask.
Sodium fluoride according to GOST 4463, a solution of 25 g/DM.
Hydrogen peroxide according to GOST 10929.
The mixture for the updates of the electrode surface; prepared by adding hydrochloric acid diluted 1:5, a few drops of hydrogen peroxide.
Aluminum brand А999 according to GOST 11069.
A standard solution of aluminum prepared by dissolving 1 g of aluminium 20 cmof hydrochloric acid diluted 1:1. After dissolution the solution was transferred to volumetric flask with a capacity of 1 DM
and topped to the mark with water.
1 cmof the solution contains 1 mg of aluminium.
Manganese sulfate (II) according to GOST 435 containing 1 mg/cmof manganese; prepared as follows: a 2.75 g of salt dissolved in 1 DM
of water.
The installation for the titrimetric determination of aluminium with amperometrical indication of the titration end (see drawing).
The installation consists of the following elements: Cup 1 with a capacity of 250−300 cmfor the test solution; two platinum indicator electrodes 2 length 17−20 mm; magnetic stirrer 3 for mixing the solution in the titration; the source current of the rechargeable battery or dry battery 8; the variable resistance 6 with a capacity of 1 mW for establishing a polarizing current of 2−10 mA; microammeter 7, consecutively connected to the circuit; a potentiometer 5connected in parallel in the circuit to measure the voltage on the electrodes; burettes 4.
The scale value of the potentiometer should be less than 5 mV, that the jump in potential at the equivalence point provides a deflection on the scale of the device is not less than 20−25 divisions.
This jump is fixed with high accuracy. The titrant (solution of nitrate of copper) enters the glass burettes with a capacity of 25 cm, and in close proximity to the equivalence point the titrant is served drop by drop from microburette.
The pH value of the titrated solution at the set pH-meter. The establishment of the pH on the acid-basic indicator or indicator paper does not provide the necessary precision of the titration, especially in the case of the titration of colored solutions.
For the titrimetric determination of aluminium you can use the setup PAT.
The titer determination of the standard copper solution
A sample of copper with a mass of 0.2 g were placed in a glass with a capacity of 250 cm, add 10 cm
to the standard solution of aluminium and copper is dissolved in 3 cm.
of nitric acid diluted 1:1. After dissolution, the sample solution was evaporated to a volume of about 1 cm
, add a 40 cm
water, 1 cm
of salt solution of manganese and 20 cm
of a solution of Trilon B.
Establish a pH 6,0−6,2 (silver-chloride electrode on a pH meter) by adding hexamine in small portions. The solution was heated 5 minutes, cooled, set the beaker on the magnetic stirrer, immerse in a solution of platinum electrodes in the variable resistance installed in the circuit current of 2−10 mA, include a potentiometer and set the arrow on the scale potentiometer so that she was in the middle of the scale. Octarepeat excess Trilon B with standard copper solution in a continuously stirred solution. The titrant enters the Cup approximately at the speed of 1 cm/min By the end of the titration a standard solution of copper is added dropwise. The titration is complete when by adding one drop of titrant (a solution of copper) hand potentiometer will deviate to the left at least 20 divisions of the scale (100 mV).
After the first titration the solution was added 20 cmof a solution of sodium fluoride, establish a pH 6,0−6,2 by adding a few drops of nitric acid, diluted 1:1, or hexamine solution and boil for 2 min. After cooling, the solution titrated with standard copper solution in the same way as in the case of binding of an excess Trilon B. Last portion of the titrant in the range of 1 cm
is added from microburette and determine the endpoint of a titration amperometric, as described above.
To establish the titer of the standard copper solution in the above-described determination is repeated at least five times.
The titer of the standard solution of copper (a), expressed in grams of aluminum per millimeter is calculated according to the formula
where — the volume of a standard solution of copper consumed in the second titration, sm
.
3.3. Analysis
A sample of alloy weighing 0.2 g is dissolved in 3 cmof a mixture of acids to dissolve. After dissolution, add 1.5 cm
of sulphuric acid and evaporate the solution to start the selection, the dense white smoke of sulfuric acid. The solution volume after evaporation should not exceed 1 cm
. A glass of cool, add 40 cm
of water, 20 cm
of solution Trilon B and further analysis are as indicated in claim 3.2.
3.4. Processing of the results
3.4.1. Mass fraction of aluminium () in percent is calculated by the formula
where the titer of a standard solution of copper, expressed in g/cm
of aluminum;
— the volume of a standard solution of copper consumed in the second titration, cm
;
— the weight of the portion of alloy,
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).
3.4.2. 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.
3.4.2 b. Control of accuracy of analysis results is carried out according to claim
3.4.2 a, 3.4.2 b. (Added, Rev. N 2).
3.4.3. The differences in the assessment of the quality of bronze used this method.
3A. TITRIMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM WITH THE SEPARATION OF ALUMINIUM FROM INTERFERING ELEMENTS AT A MERCURY CATHODE
3A.1. The essence of the method
The method is based on the introduction of the sample solution and excess Trilon B solution that forms complex with aluminium, the titration of an excess of a solution of zinc chloride in the presence kylinalove orange, the decomposition of complexonate of aluminium, by the addition of sodium fluoride and the titration of Trilon B emitted in a quantity equivalent to the aluminium content. Aluminium pre-separated from the main components of the alloy on the mercury cathode.
3A.2. Apparatus, reagents and solutions
Installation for electrolysis with a mercury cathode.
Nitric acid according to GOST 4461.
Hydrochloric acid according to GOST 3118 and diluted 1:1.
Sulfuric acid according to GOST 4204, and diluted 1:1.
The mixture of acids to dissolve; prepared as follows: three volumes of hydrochloric acid mixed with one volume of nitric acid.
Acetic acid according to GOST 61.
Ammonia water according to GOST 3760, diluted 1:1.
Sodium fluoride according to GOST 4518, saturated solution.
Ammonium acetate according to GOST 3117.
Sodium chloride according to GOST 4233.
Selenology orange.
The mixture kylinalove orange with sodium chloride in a ratio of 1:100.
Buffer solution pH 5.5−6; prepared as follows: 500 g of ammonium acetate and 20 cmof acetic acid are dissolved in water and top up with water to a volume of 1000 cm
.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652, 0.1 mol/l; prepared as follows: 37,21 g Trilon B dissolved in water when heated, transferred to a measuring flask with volume capacity of 1000 cm
and top up with water to the mark.
Aluminium GOST 11069 with a mass fraction of aluminum of not less than 99.9%.
A standard solution of aluminum; prepared as follows: 0.1 g of aluminium is dissolved in 5 cmof hydrochloric acid diluted 1:1, 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 0.001 g of aluminium.
Zinc chloride according to GOST 4529, solution 0,1 mol/DMis prepared as follows: of 13.63 g of zinc chloride dissolved in 100 cm
of water, acidified with 5 cm.
of hydrochloric acid, transferred to a measuring flask with volume capacity of 1000 cm
and top up with water to the mark.
Determination of the titer of a solution of zinc chloride.
Take 20 cmof a standard solution of aluminum in a conical flask with a capacity of 500 cm
, is diluted with water to a volume of 100 cm
, add 20 cm
of Trilon B solution, boil for 2−3 min, and add dropwise ammonia to obtain a pH of 5.5−6 on universal indicator paper. The solution was cooled, added to 10 cm
buffer solution, about 0.1 g of a mixture kylinalove orange with sodium chloride and octarepeat excess Trilon B with a solution of zinc chloride to a pink-violet color. Then add 20 cm
of a solution of sodium fluoride, boil, cooled and re-titrated with a solution of zinc chloride to obtain a pink-purple color.
The titer of a solution of zinc chloride (), expressed in grams of aluminium 1 cm
, is calculated by the formula
where is the mass of aluminium, suitable aliquote part of the solution, selected for the titration, g;
— the volume of solution of zinc chloride consumed in the second titration, sm
.
3A.3. Analysis
A sample of alloy weighing 1 g (in mass percentage of aluminum to 6%) and 0.5 g (for the mass concentration of aluminum in excess of 6%) were placed in a glass with a capacity of 250 cmand dissolved in 15 cm
of the mixture of acids to dissolve when heated.
Once dissolved, rinse walls of beaker with water, add 5 cmof sulphuric acid diluted 1:1 and the solution was evaporated until a white smoke of sulfuric acid. The residue was cooled, added to 50 cm
of water and boil to dissolve the salts. The solution was cooled and, if a precipitate has formed, it is filtered off on a medium density filter and washed with hot water acidified with a few drops of sulfuric acid. The filtrate is diluted with water to a volume of 100 cm
is transferred to the installation vessel for electrolysis with a mercury cathode and conducting electrolysis at a current density of about 1.5−2 A/DM
and a voltage of 5−6 V with simultaneous stirring of the solution. Electrolysis lead to the disappearance of the reaction on the ion of copper. After electrolysis the solution was transferred to a beaker and rinse the wall of the vessel several times with water. The solution was filtered through a filter of average density in the conical flask with a capacity of 500 cm
by washing the filter with the precipitate several times with water. To the filtrate is added an excess solution of Trilon B (approximately 40 cm
), boil and add drop by drop ammonia solution to obtain a pH of 5.5−6 on indicator paper, further analysis is carried out as described in section 3A.2 when determining the titer of a solution of zinc chloride.
3A.4. Processing of the results
3A.4.1. Mass fraction of aluminium () in percent is calculated by the formula
where is the volume of solution of zinc chloride consumed in the second titration, cm
;
the titer of a solution of zinc chloride on aluminum, g/cm
;
— the weight of the portion of alloy,
3A.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).
3A.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.
3A.4.4. Control of accuracy of analysis results is carried out according to claim
3A.4.3, 3A.4.4. (Added, Rev. N 2).
3b. TITRIMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM WITH THE SEPARATION OF ALUMINUM FROM COPPER ELECTROLYSIS WITH PLATINUM ELECTRODES
3b.1. The essence of the method
The method is based on the introduction of the sample solution and excess Trilon B solution that forms complex with aluminium and other elements, the titration of an excess of solution of nitrate of copper in the presence of 1-(2-pyridylazo)-2-naphthol (PAN), the decomposition of complexonate of aluminium by the addition of sodium fluoride and the titration of Trilon B emitted in a quantity equivalent to the aluminium content.
Aluminium pre-separated from the copper by electrolysis with platinum electrodes.
3b.2. Apparatus, reagents and solutions
Installation for electrolysis with a platinum mesh electrode according to GOST 6563.
Copper according to GOST 859, M0 and M00.
The mixture of acids to dissolve; prepared as follows: three volumes of hydrochloric acid mixed with one volume of nitric acid.
Nitric acid according to GOST 4461 and diluted 1:1 and 1:99.
Hydrochloric acid according to GOST 3118.
Sulfuric acid according to GOST 4204, diluted 1:1.
Standard copper solution: 0.1 mol/DMsolution; prepared as follows: 6,3540 g of copper is dissolved in 60 cm
of nitric acid, diluted 1:1. After dissolution, the solution was boiled to remove oxides of nitrogen and the solution gently evaporated to a volume of about 10 cm
. The solution was cooled and transferred into a measuring flask with volume capacity of 1000 cm
, is added to the mark with water and mix.
Sodium fluoride according to GOST 4518, saturated solution.
Rectified ethyl alcohol according to GOST 18300.
Sodium acetate according to GOST 199, 500 g/DM.
1-(2-Pyridylazo-2-naftol (PAN), ethanolic solution of 1 g/DM.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid 2-water (Trilon B) according to GOST 10652, 0.25 mol/DM, the solution is prepared as follows: 93,002 g Trilon B dissolved in 500 cm
of water by heating, the solution was cooled, transferred to a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
3b.3. Analysis
A sample of alloy weighing 0.5−1 g were placed in a glass with a capacity of 300 cmand dissolved in 15 cm
of the mixture of acids to dissolve when heated.
Once dissolved, rinse walls of beaker with water, add 5 cmof sulphuric acid diluted 1:1, and the solution was evaporated until a white smoke of sulfuric acid. The residue is cooled, rinse the walls of the glass with water and evaporated again until a white smoke of sulfuric acid. The residue was cooled, added to 50 cm
of water and dissolved salts when heated if a precipitate has formed, it is filtered off on a medium density filter, washed with hot water acidified with a few drops of sulfuric acid.
The solution was diluted to a volume of 150 cm, add 3 cm
boiled nitric acid and the solution is electrolyzed at a current density of 1.0 to 1.5 A/DM
and a voltage of 2−2,5 V while stirring the solution.
After the bleaching solution aside the glass with the electrolyte without the current turn-off and rinse the electrodes with water in a glass, which carried out the electrolysis. The solution was then transferred to a volumetric flask with a capacity of 500 cm, cooled, made up to the mark with water and mix. In case of separation of the precipitate the solution is filtered through a dense filter into a measuring flask with a capacity of 500 cm
, the sediment washing 7−8 times with hot nitric acid, diluted 1:99, and the solution is cooled, made up to the mark with water and mix.
Aliquot part of the solution — 200 cmis placed in a conical flask with a capacity of 500 cm
, adding 25 cm
of a solution of sodium acetate, the solution is heated nearly to boiling, add 5−10 drops of PAN solution Trilon B changes to pink-violet color in yellow and an excess of 3−5 cm
.
The solution was heated and in the case of the color change of a solution of Trilon B till the appearance of yellow color. Then the excess Trilon B octarepeat solution of nitrate of copper to change color yellow through green to blue. Add 20 cmof a solution of sodium fluoride and again boil for 2 minutes, the Solution takes a yellow-green color. The solution is cooled to a temperature of 50−60 °C and titrated with a solution of copper nitrate until the color changes from yellow-green to blue.
3b.4. Processing of the results
3b.4.1. Mass fraction of aluminium () in percent is calculated by the formula
where is the volume of solution of nitrate of copper consumed in the second titration, cm
;
0,002698 the titer of a solution of nitrate of copper by aluminium in g/cm;
— the weight of the portion of alloy, suitable aliquote part of the solution,
3b.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).
3b.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.
3b.4.4. Control of accuracy of analysis results is carried out according to claim
3b.4.3, 3b.4.4. (Added, Rev. N 2).
4. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM
4.1. The essence of the method
The method is based on formation of colored complex compounds with R eryhromycin or chromazurol S after the separation of copper by electrolysis on a platinum cathode.
4.2. Apparatus, reagents and solutions
Installation for electrolysis with platinum electrodes according to GOST 6563.
a pH meter.
Photoelectrocolorimeter or spectrophotometer.
Bromine according to GOST 4109.
Bromatologia acid according to GOST 2062.
Mix to dissolve the freshly prepared nine volumes bromatological acid is mixed with one volume of bromine.
Thioglycolic acid, 0.8% solution.
Nitric acid according to GOST 4461 and diluted 1:1.
Hydrochloric acid according to GOST 3118, diluted 1:1, and 1 n solution.
Sulfuric acid according to GOST 4204, diluted 1:1.
Hydrofluoric acid according to GOST 10484.
Ascorbic acid, freshly prepared solution of 10 g/DM.
Acetic acid according to GOST 61.
Ammonium chloride according to GOST 3773 and a solution of 20 g/DM.
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 2 cm
of sulphuric acid diluted 1: 1, diluted to 100 cm
with water.
Ammonium acetate according to GOST 3117.
Sodium acetate according to GOST 199 and a solution of 2 mol/DM.
Sodium hydroxide according to GOST 4328, solution 1 mol/DM.
Ammonia water according to GOST 3760, diluted 1:1 and 1:10.
Sodium Chernovetskiy on the other 6−09−5413, a solution of 50 g/DM.
Ammonium benzoate, a solution of 50 g/DM.
The washing liquid; is prepared as follows: 5 cmof a solution of ammonium benzoate and 1 cm
of acetic acid are dissolved in 100 cm
of water.
Buffer solution pH 6; prepared as follows: 46 g ammonium acetate and 18 g of sodium acetate and dissolve in 1 DMof water. Set the pH of the solution on the pH meter, by adding sodium hydroxide solution or acetic acid.
Urea according to GOST 6691.
Eryhromycin R, an aqueous solution 0.7 g/l; prepared as follows: 0.7 g of erioglaucine dissolved in 2 cm
of concentrated nitric acid with constant stirring for 2 minutes Add 60 cm
of water, 0.3 g of urea and incubated for 24 h in a dark place. The solution was filtered in a volumetric flask with a capacity of 1 DM
, made up to the mark with water and mix. Store in a dark bottle.
Chromazurol S, the aqueous solution 2 g/DM.
Aluminium primary brand А999 according to GOST 11069.
Standard solutions of aluminium.
Solution A, prepared as follows: 0.1 g of aluminium is dissolved by heating in 20 cmof hydrochloric acid diluted 1:1. The solution was transferred to 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 aluminum.
Solution B is prepared as follows: 5 cmmortar And transferred to a volumetric flask with a capacity of 100 cm
, add 20 cm
of hydrochloric acid diluted 1:1, made up to the mark with water and mix.
1 cmof solution B contains 0,000005 g of aluminum.
(Modified
edition, Edit. N 1).
4.3. Analysis
4.3.1. For the bronze grade Br KN1−3
The sample of bronze with a weight of 1 g was placed in a platinum Cup and poured 10 cmof nitric acid, diluted 1:1, 2−3 cm
hydrofluoric acid and evaporated to obtain a wet salts. Then pour 5 cm
of sulphuric acid diluted 1:1, and evaporated the solution to release white smoke of sulfuric acid.
A Cup of cool, dissolve salt in 30−40 cmof hot water, transfer the solution into a glass with a capacity of 300 cm
, top up with water to 100−150 cm
, 8 cm pour
nitric acid, diluted 1:1, and produce copper by electrolysis according to GOST 15027.1. The electrolyte is added 2 g of ammonium chloride, 1 cm
gentoomaniac alum solution, heated to 50−60 °C and poured a solution of ammonia diluted 1:1 prior to deposition of the precipitate of hydroxide.
The dropped sediment is allowed to settle for 10−15 minutes in a warm place, and then filtered off on a loose filter. The filter cake was washed 5−6 times with a solution of ammonium chloride. The washed precipitate is washed from the filter with a jet of hot water into a glass, which conducted the deposition. The filter was washed first 3 cmof hot hydrochloric acid diluted 1:1 and then with hot water. The filtrate collected in a beaker and the precipitate was heated until complete dissolution of the precipitate. The solution was transferred to volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Depending on the content of aluminum in a beaker with a capacity of 100 cmis taken aliquot part of the solution (table.3).
Table 3
| Mass fraction of aluminum, % | Aliquota part of the solution, see |
The weight of the portion corresponding to aliquote part g |
| From 0.005 to 0.01 |
20 |
0,2 |
| SV. 0,01 «0,025 |
10 |
0,1 |
| «Of 0.025» to 0.05 | 5 |
0,05 |
4.3.1.1. Fotometrirovanie using eryhromycin R
To aliquote part of the solution (see table.3) add water to 20 cm, 2 cm
of ascorbic acid solution, 5 cm
solution servational sodium, 20 cm
solution of erioglaucine R and set pH 6 with ammonia at pH-meter. Pour the 30 cm
buffer solution, transfer the solution into a volumetric flask with a capacity of 100 cm
and dilute to the mark with water. After 20 minutes, measure the optical density of the solution on a photoelectrocolorimeter with a green optical filter in a ditch with a length of 2 cm
or a spectrophotometer at
=535 nm in a cuvette length of 1 cm with a Solution of comparison is the solution of the reference experiment.
The aluminum content found by the calibration schedule.
When visually establishing the pH of the solution to alimatou part of the solution, placed in a volumetric flask with a capacity of 100 cm(see table.3) add water up to 25 cm
, 1 drop of solution of alum salesonline 10 cm
of a solution of thioglycolic acid and drop by drop the sodium hydroxide solution until the appearance of a purple color. Then added dropwise 1 mol/DM
hydrochloric acid solution until the disappearance of color and the excess 2 cm
, 20 cm
solution of erioglaucine, after 5 min, 30 cm
buffer solution, made up to the mark with water and then do what the decree
ANO above.
4.3.1.2. Fotometrirovanie with the use of chromazurol S
Aliquot part of the solution (see table.3) is placed in a volumetric flask with a capacity of 100 cm, add 2 cm
of ascorbic acid solution, 5 cm
solution chernovetskogo of sodium and 20 min neutralize with sodium hydroxide solution to a pH of 5−6 on the universal indicator paper. Pour 5 cm
0,1 n hydrochloric acid solution, water up to 50 cm
, 2 cm
of a solution of chromazurol S, 5 cm
of a solution of sodium acetate and add water to the mark. After 10 minutes measure the optical density in the cuvette length of 1 cm on a photoelectrocolorimeter with a green filter or on spectrophotometer at
=545 nm using the solution in the reference experiment as the solution comparison.
The aluminum content found by calibration curve
.
4.3.2. For beryllium bronze
The weight of bronze weighing 0.5 g were placed in a glass with a capacity of 300 cmand dissolved in 10 cm
of nitric acid, diluted 1:1, when heated.
After dissolution of the sample and removal of nitrogen oxides by boiling washed the side of the Cup with water, diluted the solution with water to 100−150 cm, pour 5 cm
of sulphuric acid diluted 1:1, and produce copper by electrolysis according to GOST 15027.1.
After the separation of copper in the electrolyte is added 5 g of ammonium chloride, 1 cmgentoomaniac solution of alum and heated to 50−60 °C. Heating was stopped, topped up the ammonia, diluted 1:1, prior to evaporation of the hydroxide of iron and aluminum which are dissolved, pour 1−2 cm
of acetic acid. To the solution dropwise with vigorous stirring add 20 cm
benzoate of ammonium, and boil for 1−2 min. Warm solution with koagulirovat precipitate is filtered off on two medium density filter. A glass filter and washed five times with small portions of wash liquid.
The washed precipitate is washed from the filter with a jet of hot water into a glass, which conducted the deposition. The filter was washed first 3 cmof hot hydrochloric acid diluted 1:1 and then with water, collecting the filtrate in the beaker with the sediment. After dissolution of the precipitate the solution was transferred to volumetric flask with a capacity of 100 cm
, made up to the mark with water and mix.
Depending on the aluminum content aliquote take part (see table.4) and further analysis are as indicated in claim
Table 4
| Mass fraction of aluminum, % | Aliquota part of the solution, see |
The weight of the portion corresponding to aliquote part g |
| From 0.01 to 0.025 |
20 |
0,1 |
| SV. Of 0.025 «to 0.05 |
10 |
0,05 |
| «0,05» 0,1 | 5 |
0,025 |
| «Of 0.1» to 0.25 |
2 | 0,01 |
4.3.2. For bronzes with a mass fraction of tin in excess of 0.05%
A sample of alloy weighing 0.5 g were placed in a glass with a capacity of 300 cmand dissolved in 15 cm
of the mixture to dissolve when heated. After dissolving, the solution was evaporated to dryness. Repeat twice the addition of 15 cm
of the mixture for dissolution and evaporation to dryness.
To the dry residue add 10 cmof concentrated nitric acid, the solution evaporated to a wet residue and this operation is repeated twice. To wet the cooled residue add 10 cm
of nitric acid, diluted 1:1, water to a volume of 150 cm
and produce copper by electrolysis according to GOST 15027.1. Further analysis is carried out as specified in clause
(Added, Rev. N 1).
4.3.3. Construction of calibration curve
Into beakers or volumetric flasks with a capacity of 100 cm, respectively taken 0; 1,0; 2,0; 3,0; 4,0 and 5,0 cm
of solution B, dilute with water to 20 cm
, add 1 cm
of a solution of ascorbic acid and further analysis are as indicated in the claims.4.3.1.1 and
On the found values of optical densities of solutions and their corresponding grades of aluminium to build the calibration graph.
4.4. Processing of the results
4.4.1. Mass fraction of aluminium () in percent is calculated by the formula
where is the mass of aluminum was found in the calibration schedule g;
— the weight of the portion of alloy, suitable aliquote part of the solution,
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).
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.1.
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, by comparing the results of analysis of the obtained photometric and atomic absorption methods or by a method of additives in accordance with GOST 25086.
4.4.3,
5. GRAVIMETRIC METHOD FOR DETERMINATION OF ALUMINIUM
5.1. The essence of the method
The method is based on precipitation of aluminum 8-hydroxyquinoline and weighing the dried precipitate oxyhydrate aluminum after prior separation of interfering components.
5.2. Apparatus, reagents and solutions
Installation of electrolysis with a platinum mesh cathode according to GOST 6563.
Installation of electrolysis with mercury cathode.
Crucibles filter according to GOST 23932-type TF-3−20, TF-3−32.
Mercury brand P1 according to GOST 4658.
Nitric acid according to GOST 4461, diluted 1:1.
Sulfuric acid according to GOST 4204, and diluted 1:4, 1:200 and 1:50.
Acetic acid according to GOST 61, solution 2 mol/DM.
Ammonia water according to GOST 3760 and diluted 1:50.
Ammonium chloride according to GOST 3773 and a solution of 20 g/DM.
Methyl red, alcoholic solution of 2 g/DM.
Rectified ethyl alcohol according to GOST 18300.
Potassium genesisintermedia according to GOST 4206, a freshly prepared solution of 20 g/DM.
Ammonium neccersarily according to GOST 20478.
Sodium acetate according to GOST 199.
Ammonium acetate according to GOST 3117.
8-hydroxyquinoline, a solution of 30 g/DMis prepared as follows: 30 g of reagent triturated in a mortar with a small amount of 2 mol/DM
acetic acid, and then dissolved in 1 DM
2 mol/DM
acetic acid, filtered and transferred into a flask with a capacity of 1 d
m.
5.3. Analysis
A sample of alloy weighing 1 g is placed in a beaker with a capacity of 250 cm, cover with a watch glass and dissolved by heating in 15 cm
of nitric acid, diluted 1:1.
After dissolution of the sample rinse the walls of the beaker with a little water, boil to remove oxides of nitrogen, the solution was diluted to 100−150 cm, 7 cm poured
sulphuric acid, diluted 1:4, and produce copper by electrolysis according to GOST 15027.1.
After the separation of copper in the electrolyte was added 3 g of ammonium chloride, 3−5 drops of methyl red solution, heated to boiling and carefully, drop by drop, add the ammonia until, until the color of the solution above the precipitate will be yellow. Then pour another 10 drops of ammonia and boil for 1−2 min. the Precipitate was filtered off and washed on the filter with hot solution of ammonium chloride.
The washed precipitate is dissolved on the filter in 20 cmhot sulphuric acid, diluted 1:4, which poured parts. The solution collected in the beaker, which was carried out the deposition of hydrates, neutralized with ammonia solution on methyl red and poured 1 cm
of concentrated sulfuric acid.
The solution, whose volume should not exceed 50 cm, is poured into a vessel with a mercury cathode, using as the anode a platinum spiral, and electrolyzed at a current of 4 A and a voltage of 5−6 V. the Electrolysis is continued until until the solution is fully removed the iron (drip reaction with genesisintermedia potassium on a porcelain plate or filter).
Without interrupting the current, the solution is decanted into the beaker, filtering through a funnel with filter. A mercury cathode was washed 2−3 times in 10 cmsulfuric acid, diluted 1:200, and then three times with water portions of 10 cm
. Rinse water is attached to the main part of the solution. Washing, in all cases on the mercury leave the liquid layer in 2−3 mm to ensure contact with the anode. The last washing water was removed completely.
The solution is neutralized with ammonia to methyl red indicator, flow 0,5−1,2 cmof concentrated sulfuric acid, is added 2−3 g of ammonium naternicola and heated to 70−80 °C. the Precipitate of manganese dioxide is filtered off and washed 3−5 times with sulfuric acid, diluted 1:50. To the solution add 5−10 g sodium acetate or ammonium and aluminium are precipitated with a solution of hydroxyquinoline, priliva latest in an amount of 0.5−0.7 cm
for each milligram of aluminum. The solution is heated to 60−70 °C and stand at this temperature for 3−4 h.
Sediment oxyhydrate aluminum filter on weighed filter crucible under suction, washed with hot water until complete discoloration of the wash water. The crucible with the precipitate is dried in a drying oven at 130−140 °C to constant weight and vzves
ivaut.
5.4. Processing of the results
5.4.1. Mass fraction of aluminium () in percent is calculated by the formula
where is the mass of precipitate oxyhydrate aluminum, g;
0,0587 — conversion factor oxyhydrate of aluminium on aluminium; — the weight of the portion of alloy,
5.4.2. 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).
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 (a measure of reproducibility) shall not exceed the values given in table.1.
5.4.4. Control of accuracy of analysis results
5.4.4.1. Control of accuracy of analysis results is carried out according to claim
5.4.3,
6. ATOMIC ABSORPTION METHOD for the DETERMINATION of ALUMINUM WITH a MASS FRACTION of ALUMINUM from 0.01% to 0.25%
6.1. The essence of the method
The method is based on measurement of light absorption by atoms of aluminium produced during the introduction of the analyzed solution in the flame acetylene — nitrous oxide.
6.2. Apparatus, reagents and solutions
Atomic absorption spectrometer with a radiation source for aluminium.
Installation for electrolysis with two platinum electrodes.
Nitric acid according to GOST 4461 and diluted 1:1.
Hydrochloric acid according to GOST 3118 and a solution of 2 mol/DM.
Bromatologia acid according to GOST 2062.
Bromine according to GOST 4109.
Mix to dissolve the freshly prepared nine volumes bromatological acid is mixed with one volume of bromine.
Potassium chloride on the other 6−09−5077 or sodium chloride according to GOST 4233, a solution of 10 g/DM.
Hydrogen peroxide according to GOST 10929.
Aluminium GOST 11069 with a mass fraction of aluminum of not less than 99.9%.
Standard solutions of aluminium.
Solution A, prepared as follows: 0.5 g of aluminium is dissolved by heating in 20 cmof hydrochloric acid with the addition of 2−3 cm
of hydrogen peroxide. Remove excess hydrogen peroxide by boiling, the solution was cooled, transferred to a volumetric flask with a capacity of 500 cm
and top up with water to the mark.
1 cmof the solution contains 0.001 g of aluminium.
Solution B is prepared as follows: 10 cmof the solution And transferred to a volumetric flask with a capacity of 100 cm
, add 10 cm
of 2 mol/DM
hydrochloric acid solution and add water to the mark.
1 cmof a solution contains 0.0001 g Alu
iniya.
6.3. Analysis
6.3.1. For bronzes with a mass fraction of tin up to 0.05%
A sample of alloy weighing 1 g is placed in a beaker with a capacity of 250 cmand dissolved by heating in 10 cm
of nitric acid, diluted 1:1. Nitrogen oxides are removed by boiling, the solution was cooled, diluted with water to a volume of 150 cm
and carry out electrolysis for the separation of copper GOST 15027.1. The electrolyte is evaporated to a volume of 10 cm
, cooled, transferred to a volumetric flask with a capacity of 50 cm
, add 5 cm
of a solution of potassium chloride or sodium and add water to the mark.
Measure the atomic absorption of aluminum in the flame acetylene — nitrous oxide at a wavelength of 309,3 nm parallel to the calibration solutions.
6.3.2. For bronzes with a mass fraction of tin in excess of 0.05%
A sample of alloy weighing 1 g is placed in a beaker with a capacity of 250 cmand carefully add 15 cm
of the mixture for dissolution. After dissolution the solution cautiously evaporated to dryness. Evaporation with 15 cm
of the mixture to dissolve is repeated twice, evaporating in each case dry.
To the dry residue add 10 cmof nitric acid and evaporated to syrupy state. Repeat the evaporation with 10 cm
of nitric acid, diluted with water to a volume of 150 cm
and the electrolysis is carried out according to GOST 15027.1. The electrolyte is evaporated to a volume of 10 cm
, cooled, transferred to a volumetric flask with a capacity of 50 cm
, add 5 cm
of a solution of potassium chloride or sodium and add water to the mark.
Measure the atomic absorption of aluminum, as specified in clause 6.3
.1.
6.3.3. Construction of calibration curve
Ten of the eleven volumetric flasks with a capacity of 100 cmis placed 1,0; 2,5; 5,0; 10,0; 15,0 cm
standard solution B aluminum; 2,0; 3,0; 4,0; 5,0 and 6,0 cm
standard solution And aluminum. To all flasks add 10 cm
solution of 2 mol/DM
hydrochloric acid, 10 cm
of a solution of potassium chloride or sodium, made up to the mark with water and measure the atomic absorption of aluminum, as specified in clause
6.4. Processing of the results
6.4.1. Mass fraction of aluminium () in percent is calculated by the formula
where is the concentration of aluminum was found in the calibration schedule, g/cm
;
— the volume of the final sample solution, cm
;
— the weight of the portion,
6.4.2. 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).
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 (a measure of reproducibility) shall not exceed the values given in table.1.
6.4.4. 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 comparing the results of analysis obtained by atomic absorption, gravimetric or photometric method of analysis in accordance with GOST 25086.
6.4.3,
7. ATOMIC ABSORPTION METHOD for the DETERMINATION of ALUMINUM WITH a MASS FRACTION of ALUMINUM from 3% to 13%
7.1. The essence of the method
The method is based on measurement of light absorption by atoms of aluminium produced during the introduction of the analyzed solution in the flame acetylene — nitrous oxide.
7.2. Apparatus, reagents and solutions
Atomic absorption spectrometer with a radiation source for aluminium.
Nitric acid according to GOST 4461.
Hydrochloric acid according to GOST 3118 and a solution of 2 mol/DM.
Hydrogen peroxide according to GOST 10929.
Potassium chloride on the other 6−09−5077 or sodium chloride according to GOST 4233, a solution of 10 g/DM.
Aluminium GOST 11069 with a mass fraction of aluminum of not less than 99.9%.
A standard solution of aluminum; prepared as follows: 0.5 g of aluminium is dissolved by heating in 20 cmof hydrochloric acid with the addition of 2−3 cm
of hydrogen peroxide solution. Remove excess hydrogen peroxide by boiling, the solution was cooled, transferred to a volumetric flask with a capacity of 500 cm
and top up with water to the mark.
1 cmof the solution contains 0.001 g of aluminium.
7.3. Analysis
7.3.1. A sample of alloy weighing 0.25 g were placed in a glass with a capacity of 150 cmand dissolved by heating in 10 cm
of nitric acid with a few drops of hydrochloric acid.
Nitrogen oxides are removed by boiling, the solution was cooled, transferred to a volumetric flask with a capacity of 250 cm, adding 25 cm
of a solution of potassium chloride or sodium and add water to the mark.
Measure the atomic absorption of aluminum in the flame acetylene — nitrous oxide at a wavelength of 309,3 nm parallel to the calibration solutions.
7.3.2. Construction of calibration curve
In seven of the eight volumetric flasks with a capacity of 100 cmplaced 2,0; 4,0; 6,0; 8,0; 10,0; 12,0 and 14.0 cm
standard solution aluminum.
To all flasks add 10 cmsolution of 2 mol/DM
hydrochloric acid, 10 cm
of a solution of potassium chloride or sodium, made up to the mark with water and measure the atomic absorption of aluminum, as specified in clause
7.4. Processing of the results
Processing of results conducted as specified in claim 6.4.
Sec. 6, 7. (Added, Rev. N 1).
7.5. The method used in the differences in assessing the quality of tin-bronze.
(Added, Rev. N 2).
