71.080.50 - Anhydrides

Gives general instructions and specifies methods of analysis. The methods to be used are determination of destillation yield, of bromine number, of arsenic content, of permanganate index, of dichromate index, the measurement of colour, titrimetric determination of acetic anhydride content, gravimetric determination of ash, spectrometric determination of phosphate content and visual limit tests for inorganic chlorides, sulphates and heavy metals including iron, sulphuric acid colour test. It results from the combination into one single decument of draft International Standard ISO/DIS 754 part 1 to 10; it cancels and replaces ISO Recommendation R 754-1968.

The principle consists in the dissolution of a test portion in diluted standard volumetric sodium hydroxide solution and titration with standard volumetric sodium hydroxide solution in presence of phenolphthalein as indicator. - ISO 1390, Parts 1 to 6, replace ISO Recommendation R 1390-1970.

The principle is based on the dissolution, in hot hydrochloric acid, of the residue from the determination of the ash of a test portion (see ISO 1390/5). Reduction, by hydroxylammonium chloride, of the iron(III) contained in the solution thus obtained, formation of the coloured complex iron(II)-2,2'bipyridyl in a buffered medium. Photometric measurement of the coloured complex at a wavelength of about 510 nm. - ISO 1390, Parts 1 to 6, replace ISO Recommendation R 1390-1970.

The document also specifies the method to be used for the determination of the crystallizing point. Before carrying out the tests, the sample shall be grind to a fine powder and shall be mixed thoroughly. Exposure to moist air may lead to the formation of maleic acid. - ISO 1390, Parts 1 to 6, replace ISO Recommendation R 1390-1970.

The principle is based on the measurement of colour, by the method specified in ISO 2211, of a test portion in the molten state. The results are expressed in Hazen units. - ISO 1390, Parts 1 to 6, replace ISO Recommendation R 1390-1970.

The principle consists in burning a test portion and heating in a furnace controlled at (600 30) °C, until all carbonaceous matter has disappeared, to constant mass. The residue may be retained for the determination of iron. - ISO 1390, Parts 1 to 6, replace ISO Recommendation R 1390-1970.

The procedure is based on the potentiometric titration of the free acidity in a test portion with a standard volumetric triethylamine solution in anhydrous methyl ethyl ketone (butanone). - ISO 1390, Parts 1 to 6, replace ISO Recommendation R 1390-1970.

The principle consists in treatment of a test portion in acid solution with excess standard volumetric potassium bromide-potassium bromate solution, addition of potassium iodide solution and titration of the liberated iodine with a standard volumetric solution of sodium thiosulphate. - Replaces ISO Recommendation R 761-1968.

The principle is based on the dissolution, in hot hydrochloric acid, of the residue from the determination of the ash of a test portion (see ISO 1389/8). Reduction, by hydroxylammonium chloride, of the iron(III) contained in the solution thus obtained, formation of the coloured complex iron(II)-2,2'bipyridyl in a buffered medium. Photometric measurement of the coloured complex at a wavelength of about 510 nm. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The principle consists in the dissolution of a test portion in an excess of standard volumetric sodium hydroxide solution and back-titration of the excess with a standard volumetric hydrochloric acid solution using phenolphthalein as indicator. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

This method is not specific for maleic anhydride. The polarographic method specified in part 7 should be used. The principle is based on the oxidation of unsaturated organic acids and anhydrides in a test portion with an excess of cold standard volumetric potassium permanganate solution in the presence of sulphuric acid, followed by iodometric determination of the potassium permanganate remaining. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The principle is based on the measurement of colour, by the method specified in ISO 2211, of a test portion in the molten state. The results are expressed in Hazen units. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The test sample is treated with sulphuric acid solution in a conical flask in boiling water bath for 3 h. The colour is measured by the method specified in ISO 2211. The results are expressed in Hazen units. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The principle consists in the dissolution of a test portion in acetone, removal of 1,4-naphthoquinone present in the solution by extraction with benzene. Polarographic measurement of the aqueous solution and determination of the mass of maleic anhydride by means of the calibration graph. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The principle consists in the development of a pink colour by heating a test portion containing 1,4-naphtoquinone with tin(II) chloride, and comparison of the colour produced with a series of prepared reference colours. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The principle is based on the measurement of the colour of a test portion, by the method specified in ISO 2211, after a specified heat treatment. The test sample is maintained in a colorimetric tube in an electrically heated aluminium block, controlled at (250 3) °C for 90 min, in the molten state. The results are expressed in Hazen units. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The principle of the method consists in the potentiometric titration of a test portion not exceeding 10 g and containing not more than 0.150 g of phthalic acid, with a standard volumetric solution of triethylamine in anhydrous butanone. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

This document also specifies a method to be used for the determination of the crystallizing point. Before carrying out the analysis and tests, the sample shall be grind to a fine powder and mixed thoroughly. Exposure to moist air may lead to the formation of phthalic acid. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.

The principle consists in burning a test portion and heating in a furnace controlled at (600 30) °C, until all carbonaceous matter has disappeared, to constant mass. - ISO 1389, Parts 1 to 11, replace ISO Recommendation R 1389-1970.