ISO 900:1977 pdf download.Aluminium oxide primarily used for the production of aluminium — Determination of titanium content — Diantipyrylmethane photometric method.
1 SCOPE AND FIELD OF APPLICATION
ISO 900:1977 specifies a diantipyrylmethane photometric method for the determination of the titanium content of aluminium oxide primarily used for the production of aluminium.
The method is applicable to products having a titanium content, expressed as titanium dioxide (TiO2)，equal to or greater than 0, 001 % (m/m).
2 REFERENCES
ISO 802, Aluminium oxide primarily used for the production of aluminium – Preparation and storage of test samples.
ISO 804, Aluminium oxide primarily used for the production of aluminium – Preparation of sample solution for analysis – Method by alkaline fusion
3 PRINCIPLE
Alkaline fusion of a test portion and extraction of the fused mass with sulphuric acid solution. Formation of the titanium-diantipyrylmethane complex in approximately 4.6 N sulphuric acid solution.
Photometric measurement of the coloured complex at a wavelength of approximately 420 nm.
5 APPARATUS
Ordinary laboratory apparatus and
5.1 Burette, graduated in 0,05 ml, complying with the requirements of ISO/R 385.
5.2 Spectrophotometer, or
5.3 Photoelectric absorptiometer, fitted with suitable filters, having maximum absorption at about 420 nm.
6 PROCEDURE
6.1 Preparation of the test solution (principal solution P)
Proceed in accordance with sub-clauses 6.1 6.2 and 6.3 of ISO 804, replacing the nitric acid solution (4.5 of ISO 804) by the sulphuric acid solution(4.3) and diluting the principal solutions to 250 ml.
6.2 Test portion
Place 50,0 ml of the test solution (6.1)， containing 1,000 g of the dried sample (see sub-clause 3.3 of ISO 802)， in a 100 ml one-mark volumetric flask.
NOTE-If the TiO, content is greater than 0,01 %(m/m)， reduce the test portion proportionately and take this into account in the calculation of the results.
6.3 Preparation of the calibration graph
3.3.1 Preparation of the standard colorimetric solutions for photometric measurements using 4 cm cells.
Into a series of seven 100 ml one-mark volumetric flasks transfer, by means of the burette (5.1)，the volumes of the standard titanium solution (4.10) shown in the following table.
Add 25 ml of the sulphuric acid solution(4,4)to each flask. Dilute with water to about 70 ml, add 3 ml of the ascorbic acid solution (4.5)and 3 drops of the copper() sulphate solution (4.6)and mix. Allow to stand for 20 min add 10 ml of the diantipyrylmethane solution (4.7)， dilute to the mark and mix.
6.3.2 Photometric measurements
After at least 40 min, carry out the photometric measurements using the spectrophotometer (5.2) at a wavelength of about 420 nm or the photoelectric absorptiometer (5.3) fitted with suitable filters, after having adjusted the instrument to zero absorbance against the compensation solution.
NOTE – The absorbance of the solution is stable for about 24 h.
6.3.3 Plotting of the calibration graph
Plot a graph having, for example, the values of the masses, in milligrams, of titanium dioxide (TiO2)contained in 100 ml of standard colorimetric solution, as abscissae and the corresponding values of absorbance as ordinates.ISO 900:1977 pdf download.