GOST 741.11-80
STATE STANDARD OF THE USSR
COBALT
METHOD FOR THE DETERMINATION OF ALUMINIUM
COBALT
Method for the determination of aluminium
GOST 741.11−80
Group B59
AXTU 1709
(code AXTU introduced by Change No. 1, promulgated by the Decree of Gosstandart of the USSR from
Replace GOST 741.11−69
The validity of
from July 1, 1981
prior to July 1, 1986
This standard specifies the flotation-photometric method for the determination of aluminum at a mass proportion from 0.0004 inch to 0.2%.
(the chapeau as amended by Changes No. 2, approved. By the decree of Gosstandart of the USSR from
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 741.1−80.
(as amended by Change No. 1, promulgated by the Decree of Gosstandart of the USSR from
2. THE PHOTOMETRIC METHOD FOR THE DETERMINATION OF ALUMINIUM
(from 0.0001 to 0.002%)
Section 2 was deleted 1 may 1992. — Amendment No. 2, approved. By the decree of Gosstandart of the USSR from
3. FLOTATION-PHOTOMETRIC DETERMINATION OF ALUMINIUM
(as amended by Changes No. 2, approved. Resolution
Gosstandart of the USSR from
3.1. The essence of the method
The method is based on measurement of absorption of complex compounds of aluminium with eryhromycin-R at a wavelength of 535 nm after prior separation of the aluminium by flotation in the form of complex compounds with eryhromycin-R.
(section 3.1and introduced by the Change in N 2, approved. By the decree of Gosstandart of the USSR from
3.1. Apparatus, reagents and solutions
Spectrophotometer or photoelectrocolorimeter of any type.
a pH meter.
Hydrochloric acid according to GOST 14261−77, the solutions are 0.2 M and 1:4.
Nitric acid according to GOST 11125−84, a solution of 1:1.
Sulfuric acid according to GOST 4207−75, a solution of 1:1.
Ascorbic acid, a solution of 20 g/dm3, use freshly prepared solution.
Acetic acid according to GOST 18270−72.
Ammonia water according to GOST 3760−79 and solutions 1:1 and 1:10.
Sodium chloride according to GOST 4233−77.
Sodium nitrate according to GOST 4168−79.
Sodium acetate according to GOST 199−78.
Acetate buffer solution with a pH of 6.2: 200 g of sodium acetate in portions of 10 — 20 g dissolved in 500 cm3 of water, pour 4 cm3 of acetic acid, transferred to a measuring flask with volume capacity of 1000 cm3, made up to the mark with water and filtered.
Eryhromycin-R, a solution of 0.75 g/dm3: 0.375 g of the reagent was placed in a quartz beaker, add 12.5 g of sodium chloride, 12.5 g of sodium nitrate, 1 cm3 of nitric acid and 200 cm3 of water.
Bwithe thoroughly mixed and allowed to stand for 12 — 24 hours Then filtered through a dense filter into a measuring flask with volume capacity of 500 cm3 and adjusted to the mark with water.
The solution is used within two weeks.
Benzene according to GOST 5955−75.
Aluminium GOST 11069−74.
Standard solutions of aluminium
Solution A: 0,1000 g of aluminum is dissolved at the temperature 40 — 60 °C 10 cm3 of hydrochloric acid, add 3 to 4 drops of nitric acid, transferred to a volumetric flask with a capacity of 500 cm3, made up to the mark with water and transferred in a dry plastic container.
1 cm3 of solution contains gof aluminum.
Solution B: 5.0 cm3 of the solution And transferred to a volumetric flask with a capacity of 500 cm3 and adjusted to the mark with water.
1 cm3 of solution contains gof aluminum.
The solution is prepared before use.
All the solutions were stored in polyethylene containers.
(clause 3.1 as amended by Changes No. 2, approved. By the decree of Gosstandart of the USSR from
3.2. Analysis
A portion of the cobalt mass (see table. 1) is placed in a quartz glass with a capacity of 250 — 300 cm3 and decomposed by heating in 10 to 15 cm3 of nitric acid, diluted 1:1, then add 5 cm3 of sulphuric acid diluted 1:1, and gently evaporated to dryness. The glass is removed from the plate and after cooling poured 20 cm3 of water, dissolve the sulfate salt in low heat.
(in edition of Changes No. 1, promulgated by the Decree of Gosstandart of the USSR from
Table 1
─────────────────────────┬──────────┬────────────┬────────────────
Mass fraction of aluminum, %│ Weight │Volume measuring│Aliquotapart
│sample, g│ flasks, cm3 │ of solution, cm3
─────────────────────────┼──────────┼────────────┼────────────────
From 0.0005 to 0.0008 inch │1 │- │-
SV. 0,0008 «0,0018 │0,5 │- │-
«0,0018» 0,0028 │1 │100 │25
«0,0028» 0,01 │1 │100 │10
«0,01» 0,03 │0,5 │250 │10
«0,03» 0,07 │0,2 │250 │10
«0,07» 0,15 │0,2 │250 │ 5
«0,15» 0,20 │0,2 │500 │ 5
(as amended by Change No. 1, promulgated by the Decree of Gosstandart of the USSR from
Aliquot the solution or part of the solution was transferred to a beaker with a capacity of 50 cm3, add 1 cm3 of ascorbic acid solution, add 5 cm3 of a solution of eryhromycin-R and 15 cm3 of buffer solution. Set the pH of the solution 6,0 +/- 0,2 on the pH meter by adding drop by drop a solution of ammonia 1:10 or 0.2 M hydrochloric acid. The solution was quantitatively transferred to a separating funnel, pour 15 cm3 of benzene and shake the funnel for 1 min (the precipitate of aluminium with a reagent blue-purple color). After separation of phases the aqueous layer is drained into a second separatory funnel, washed benzene layer 5 cm3 buffer solution and poured it into the solution. From the test solution re-conduct flotation with a fresh portion of benzene. The aqueous layer is discarded and the organic phases combined. In the second separating funnel, containing the remains of the walls of the precipitate of aluminium, pour 2 cm3 of 0.2 M hydrochloric acid, shake the separating funnel, poured the acid with dissolved aluminium in the first separating funnel. The precipitate of aluminium is dissolved by shaking, poured the solution into a clean beaker with a capacity of 50 cm3. Relocatio repeat 2 cm3 of 0.2 M hydrochloric acid, and then the benzene layer was washed with 2 — 3 cm3 of water, which drained into the same beaker.
(as amended by Change No. 1, promulgated by the Decree of Gosstandart of the USSR from
To the beaker add 0.5 cm3 of the ascorbic acid solution, 2 cm3 of a solution of eryhromycin-R, 15 cm3 of buffer solution set pH 6,0 +/- 0,2 and transfer the solution into a measuring flask with volume capacity of 50 cm3, made up to the mark with water and measure the light absorptionof the solution at a wavelength of 535 nm.
(as amended by Change No. 1, promulgated by the Decree of Gosstandart of the USSR from
The complex is stable for 30 min.
(as amended by Changes No. 2, approved. By the decree of Gosstandart of the USSR from
As a solution comparison, use water.
(as amended by Changes No. 2, approved. By the decree of Gosstandart of the USSR from
A lot of aluminium in the sample solution found by the calibration schedule, adjusted for the weight of aluminium in solution in the reference experiment.
(as amended by Changes No. 2, approved. By the decree of Gosstandart of the USSR from
3.3. The construction of the calibrationgraph
In a volumetric flask with a capacity of 50 cm3 pour six drops of hydrochloric acid 1:4 and injected 0; 0,50; 1,00; 2,00; 3,00; 4,00; 5,00 cm3 of standard solution B, which corresponds to (0; 0,001; 0,002; 0,004; 0,006; 0,008; 0,010) g of aluminum, add 5 cm3 of water, 0.5 cm3 of the ascorbic acid solution and then in accordance with clause 3.2.
According to the obtained values of absorption and their corresponding masses of the aluminium build of the calibration graph, adjusted for the value of the light absorption of the calibration solution containing no aluminum.
(item 3.3 as amended by Changes No. 2, approved. By the decree of Gosstandart of the USSR from
3.4. Processing of the results
3.4.1. Mass fraction of aluminum (X) in percent is calculated by the formula
,
where is the mass of aluminum was found in the calibration schedule g;
m — weight of cobalt, g.
3.4.2. Allowable absolute discrepancies in the results of parallel measurements characterizing the convergence of the method (d), and the results of two analyses that characterize the reproducibility of the method (D), shall not exceed the values specified in table. 2.
Table 2
────────────────────────────┬─────────────────────────────────────
Mass fraction of aluminum, % │allowable Absolute differences, %
├───────────────────────┬─────────────
│ d │ D
────────────────────────────┼───────────────────────┼─────────────
From 0,0004 to 0,0008 incl.│0,0033 │0,0004
SV. 0,0008 «0,0015» │of 0.0005 │0,0007
«0,0015» 0,003 «│0,001 │0,001
«0,003» 0,006 «│0,002 │0,003
«0,006» 0,012 «│0,004 │0,004
«0,012» 0,030 «│0,008 │0,008
«0,030» 0,060 «│0,015 │0,015
«0,06» 0,12 «│0,02 │0,02
«0,12» 0,20 «│0,03 │0,03
(paragraph 3.4.2 as amended by Changes No. 2, approved. By the decree of Gosstandart of the USSR from
