ISO 3262-20:2000 pdf download
ISO 3262-20:2000 pdf download.Extenders for paints – Specificationsand methods of test— Part 20: Fumed silica.
Wet the ignited test portion in the platinum dish with 2 ml to 3 ml of water, add 1 ml of sulfuric acid (6.2.1) and 15 ml of hydrofluoric acid (6.2.2) and evaporate to a syrup on the infrared evaporator (6.3.3), taking care to avoid loss by spitting. Allow to cool and wash the sides down with small quantities of water. Then add a further 10 ml of hydrofluoric acid and evaporate to dryness. If the evaporation of the silicon tetrafluoride is not complete, add a further 10 ml of hydrofluoric acid and evaporate to dryness again.
Heat the residue until white fumes are no longer evolved, then ignite for 30 mm in the muffle furnace at (1 000 ± 20) °C. Remove from the furnace, allow to cool in the desiccator and weigh to the nearest 0,2 mg (1112).
6.5 Expression of results
Calculate the silica content w(Si02), expressed as a percentage by mass, using the equation
is the mass, in grams, of the test portion after ignition;
in2 is the mass, in grams, after treatment with hydrofluoric acid and ignition.
Calculate the mean of the two determinations and report the result to the nearest 0,1 %.
6.6 Precision
No precision data are currently available.
7 Determination of aluminium oxide, titan ium(IV) oxide and iron(lll) oxide contents by
spectrometry
7.1 Principle
A test portion is treated with sulfuric acid and hydrofluoric acid in a platinum dish. The resulting silicon tetrafluoride is volatilized and the residue is dissolved in hydrochloric acid. After diluting with water to a constant, known volume, the Al, Ti and Fe impurities are determined either by flame atomic absorption spectrometry (FAAS) or by inductively coupled plasma atomic emission spectrometry (ICP-AES), depending on which instrument is available in the laboratory.
NOTE The advantages of the ICP-AES method include its wide dynamic range and multi-element capabilities. Both methods (FAAS and ICP-AES) are relative analytical techniques. For quantitative analytical results, both measurement techniques must be calibrated using standard matching solutions.
7.2 Reagents and materials
Use only reagents of recognized analytical grade except for acids, which shall be ultrapure, and use only water of at least grade 3 purity as defined in ISO 3696.
7.2.1 Sulfuric acid, diluted 1 + 1.
Add 1 part by volume of concentrated sulfuric acid, approximately 96 % (iidm), p 1,84 g/ml, slowly to 1 part by volume of water.
7.2.2 Hydrofluoric acid, concentrated, approximately 40 % (m/in), p 1,13 g/ml.
7.2.3 Hydrochloric acid, concentrated, approximately 30 % (m/in), p 1,15 g/ml.
7.2.5 Caesium chloride buffer solution.
Dissolve 50 g of caesium chloride in approximately 500 ml of water and add 50 ml of concentrated hydrochloric acid (7.2.3). Make up to 1 000 ml with water and mix well.
7.2.6 Standard stock solutions, containing 1 ,000 g/l of aluminium, titanium and iron, respectively.
Store each solution in a fluorinated-polyethylene/polypropylene (FEP) bottle.
7.2.7 Standard solutions, containing 10 mg of the element per litre.
Prepare these solutions on the day of use.
Pipette 1 ml of the appropriate standard stock solution (see 7.2.6) into a 100 ml one-mark volumetric flask, add
10 ml of concentrated hydrochloric acid (7.2.3), make up to the mark with water and mix well.
1 ml of the standard solution contains 10 pg of the element concerned.
Prepare a more dilute or more concentrated standard solution, if necessary, depending on the concentration of Al,
Ti or Fe in the product under test.
7.2.8 Ethanol, 96 % (V/V).
7.2.9 Acetylene (C2H2), commercial grade, in a steel cylinder.
7.2.10 Compressed air.
7.2.11 Dinitrogen oxide (N20), commercial grade, in a steel cylinder.
7.3 Apparatus
Use ordinary laboratory apparatus and glassware, together with the following:
7.3.1 Flame atomic absorption spectrometer (FAAS), suitable for measurements at the following wavelengths:
309,3 nm for aluminium (Al),
— 364,3 nm for titanium (Ti), 248,3 nm for iron (Fe),
fitted with a suitable burner fed with
— an N20/C2H2 mixture for Al and Ti determinations,
— a C2H2iair mixture for Fe determinations,
and also fitted with hollow-cathode lamps for the elements Al, Ti and Fe and a deuterium background corrector.
7.3.2 Inductively coupled plasma atomic emission spectrometer (ICP-AES), preferably with high resolution ( 0,01 nm), automatic control of all plasma operating functions and a computer-controlled signal compensation system.
7.3.3 Platinum dish.
7.3.4 100 ml one-mark volumetric flasks, complying with the requirements of ISO 1042.
7.3.5 Pipettes,calibrated, of suitable volumes (see 7.4), complying with the requirements of lSO 648.7.4Procedure
7.4.1Preparation of standard matching solutions
Introduce, with pipettes (7.3.5), suitable volumes of the standard solutions (7.2.7) into a series of several 100 mlone-mark volumetric flasks (7.3.4), add 10 ml of concentrated hydrochloric acid (7.2.3), make up to the mark withwater and mix well. For the aluminium and titanium determination by FAAS, add 5 ml of caesium chloride solution(7.2.5) before making up to 100 ml with water.
