71.060.40 - Bases

A test portion is introduced into a solution of boric acid and the solution obtained is titrated with a standard volumetric solution of sulfuric acid in the presence of methyl red as indicator. The method is applicable to solutions containing not more than 35 % (m/m) of ammonia.

A test portion is evaporated in a tared platinum dish and the residue is weighed after drying at 105 2 °C. The method is applicable to solutions containing not more than 35 % (m/m) ammonia.

Covers a method applicable to liquid or solid products having mercury contents greater than 0,02 mg/kg. The principle of determination is based on oxidation of the mercury contained in a test portion to mercury(II) ions by potassium permanganate in the presence of sulphuric acid, reduction of the excess oxidant by hydroxylammonium chloride, reduction of the mercury(II) ions to mercury by tin(II) chloride, entrainment of the mercury in air or nitrogen, passage of the gaseous mixture through a measuring cell, and measurement of the absorption at a wavelength of 253,7 nm.

Applicable to products having contents, expressed as CO2 , of more than 0.01 % (m/m). Relates to a procduct containing neither sulphides nor chlorates or only sulphides or only chlorates. Preliminary test by boiling an acidified test sample in the presence of methyl orange and with a lead acetate paper strip in the vapour. The sulphides blacken the paper and chlorates delolourize the methyl orange. Products containing neither sulphides nor chlorates: liberation of carbon dioxide by acidification and heating. Entrainment in a flow of gas and absorption in an excess of barium hydroxide solution. Titration of the excess barium hydroxide solution with a standard volumetric hydrochloric acid solution in the presence of thymolphthalein as indicator.

Indicates the conditions under which the test sample shall be prepared and relates to particular properties which require particular precausions: the samples shall be taken rapidly in a dry atmosphere, storage in an airtight bottle. The bottle shall be made from an inert material such as polyethylene. Preparation of the main solution with distilled carbonat- free water. If the silica content is to be determined the test portion shall be dissolved in a container made from silica-free material such as polyethylene or silver. Cancels and replaces ISO Recommendations R 977/1969 and R 978/1969.

Method for determination of the titre; this is expressed conventionally as percentages by mass of NaOH, a) as total alkalinity and b) as caustic alkalinity, corresponding to the total alkalinity less the alkalinity due to carbonates. The principle consists in titration of the total alkalinity with standard volumetric hydrochloric acid solution in the presence of methyl orange as indicator. Calculation of the two amounts a) and b). The mass of carbon dioxide is determined by the method specified in ISO 3196. This method has also been approved by the IUPAC. - Cancels and replaces ISO Recommendation R 979-1969 of which it constitutes a technical revision.

Provides certain indications relating to the sampling and indicates the conditions under which the test sample should be prepared The special properties which make particular precautions essential such as hygroscopic characteristics, absorption of carbon dioxide, corrosive action on containers, should be stressed. The preparation of the main solution is carried out by dissolution of the test portion in distillated water or by transfer of the liquid test portion directly and quantitatively in a one-mark volumetric flask. Cancels and replaces ISO Recommendation R 988-1969 and ISO recommendation R 989-1969.

The method is applicable to products of which the chloride content is greater than 0.005 % (m/m). The procedure based on titration of the chloride ions with mercury(II) nitrate in the presence of diphenylcarbazone as indicator. - Replaces ISO Recommendation R 981-1969.

Covers a method applicable to liquid or solid products having mercury contents greater than 0,05 mg/kg. The principle of determination is based on oxidation of the mercury contained in a test portion to mercury(II) ions by potassium permanganate in the presence of sulphuric acid, reduction of the excess oxidant, extraction in chloroform of the complex formed, and photometric measurement of the complex at a wavelength of about 490 nm.

Applicable to products having contents of more than 2.5 mg Ca/kg and 0.5 mg Mg/kg if an acetylene-air flame is used or 0.6 mg Ca/kg and 1.0 mg Mg/kg if an acetylen-dinitrogen monoxide flame is used. The principle consists in the acidification of a test portion with hydrochloric acid, aspiration of the solution into an acetylene-dinitrogen monoxide flame or acetylene-air flame. In the latter case, addition of lanthanum ions in order to suppress certain interferences. Measurement of the absorption of the 422.7-nm and 285.2-nm lines emitted by calcium and magnesium hollow-cathode lamps.

Applicable to products having contents of more than 2.5 mg Ca/kg and 0.5 mg Mg/kg if an acetylene-air flame is used or 0.6 mg Ca/kg and 1.0 mg Mg/kg if an acetylen-dinitrogen monoxide flame is used. The principle consists in the acidification of a test portion with hydrochloric acid, aspiration of the solution into an acetylene-dinitrogen monoxide flame or acetylene-air flame. In the latter case, addition of lanthanum ions in order to suppress certain interferences. Measurement of the absorption of the 422.7-nm and 285.2-nm lines emitted by calcium and magnesium hollow-cathode lamps.

The method is applicable to products having a calcium content equal to or greater than 0.002 % (m/m). The principle consists in titration of the calcium with a standard volumetric solution of the disodium salt of (ethylenedinitrilo)tetraacetic acid (EDTA disodium salt) in the presence of 2,2'-(ethylenedinitrilo)diphenol Äglyoxal-bis-(2-hydroxyanil)Ü as indicator, after elimination of impurities which may hinder the determination. - Replaces ISO Recommendation R 986-1969.

The method is applicable to products having a calcium content equal to or greater than 0.002 % (m/m). The principle consists in titration of the calcium with a standard volumetric solution of the disodium salt of (ethylenedinitrilo)tetraacetic acid (EDTA disodium salt) in the presence of 2,2'-(ethylenedinitrilo)diphenol Äglyoxal-bis-(2-hydroxyanil)Ü as indicator, after elimination of impurities which may hinder the determination. - Replaces ISO Recommendation R 997-1969.

The method is applicable to products having silica contents exceeding 10 mg/kg. The principle is based on the formation of yellow oxidized silico-molybdic complex in a strongly acid medium, in the presence of boric acid to suppress interference by fluorides. Selective reduction of this complex with a mixture of aminonaphtholsulphonic acid (4-amino-3-hydroxynaphthalene-1-sulphonic acid), sodium metabisulphite and sodium sulphite, in the presence of oxalic acid and in a strongly acid medium so as to suppress interference by phosphates. Photometric measurement of the blue-coloured complex at a wavelength of about 795 nm.

Applicable to products the content of which, expressed as sulphate, is equal or more than 5 mg/kg. The principle consists in the reduction of the sulphur compounds to hydrogen sulphide by heating with a mixture of hydriodic acid and hypophosphorous acid. Distillation of the hydrogen sulphide by a current of purified oxygen-free nitrogen in a mixture of sodium hydroxide and acetone. Titration of the sulphide with standard volumetric mercury(II) nitrate solution in the presence of dithizone as indicator.

Applicable to products the content of which, expressed as sulphate, is equal or more than 5 mg/kg. The principle consists in the reduction of the sulphur compounds to hydrogen sulphide by heating with a mixture of hydriodic acid and hypophosphorous acid. Distillation of the hydrogen sulphide by a current of oxygen-free nitrogen in a mixture of sodium hydroxide and acetone. Titration of the sulphide with standard volumetric mercury(II) nitrate solution in the presence of dithizone as indicator.

Applicable to products having contents, expressed as chlorine, between 2 mg/kg and 50 mg/kg. For contents exceeding 50mg/kg the method specified in ISO 992 shall be used. The principle consists in quantitative displacement of the thiocyanate (SCN- ) ions of the mercury(II) thiocyanate by the cloride (Cl- ) ions contained in the test portion. Reaction of the thiocyanate ions with iron(III) nitrate to form iron(III) thiocyanate (red). Photometric measurement of the colour at a wavelength of about 450 nm.

Applicable to products having contents, expressed as chlorine, between 2 mg/kg and 50 mg/kg. For contents exceeding 50 mg/kg the method specified in ISO 981 shall be used. The principle consists in the quantitative displacement of the thiocyanate ions of the mercury(II) thiocyanate by the cloride ions contained in the test portion. Reaction of the thiocyanate ions with iron(III) nitrate to form iron(III) thiocyanate (red). Photometric measurement of the colour at a wavelength of about 450 nm.

The method is applicable to products the chloride content of which is greater than 25 mg/kg. The procedure is based on titration of the chloride ions with mercury(II) nitrate in the presence of diphenylcarbazone as indicator. - Replaces ISO Recommendation R 992-1969.

Specifies a method that is more sensitive and more widely used than the 2,2'-bipyridyl method. It is applicable to products having iron contents equal to or greater than 0.5 mg/kg. The principle is based on the reduction of trivalent iron by hydroxylammonium chloride, formation of a bivalent iron/1,10-phenanthroline complex in a buffered system. Photometric measurement of the coloured complex at a wavelength of about 510 nm. This method has also been approved by the IUPAC. - Cancels and replaces ISO Recommendation R 983-1969.

The method is applicable to products having silica contents exceeding 10 mg/kg. The principle is based on the formation of yellow oxidized silico-molybdic complex in a strongly acid medium, in the presence of boric acid to suppress interference by fluorides. Selective reduction of this complex with a mixture of aminonaphtholsulphonic acid (4-amino-3-hydroxynaphthalene-1-sulphonic acid), sodium metabisulphite and sodium sulphite, in the presence of oxalic acid and in a strongly acid medium so as to suppress interference by phosphates. Photometric measurement of the blue-coloured complex at a wavelength of about 795 nm.

The method is applicable to products having sodium contents greater than 0.01 % (m/m). The principle consists in the dissolution of a test portion, followed by acidification to ph value 1. Atomization of the obtained solution in the burner of a flame spectrophotometer. Measurement of the intensity of the radiation emitted at 589 nm; comparison with the intensity obtained for standard sodium chloride solutions, the acidity and potassium chloride content of which are equivalent to that of the test solution. - Cancels and replaces ISO Recommendation R 1550-1970.

Applicable to products having CO2 contents of more than 0.01 % (m/m). Three cases are envisaged. The product containing neither sulphides nor chlorates or containing sulphides or chlorates. The principle in presence of neither sulphides nor chlorates consists in liberation of carbon dioxide in a flow of gas and absorption in an excess of standard volumetric barium hydroxide solution. Titration of the excess with standard volumetric hydrochloric acid solution in the presence of thymolphthalein as indicator. In presence of sulphides, pretreatment by oxidation of the sulphides by hydrogen peroxide and boiling, in presence of chlorates, pretreatment by reduction of the chlorates to chlorides by the addition of iron(II) sulphate.

Method for determination of the titre, conventionally expressed as percentages by mass of KOH. There are three ways: a) total alkalinity, b) caustic alkalinity corresponding to the total alkalinity less the alkalinity due to carbonates and c) actual potassium hydroxide corresponding to the total alkalinity less the alkalinity due to carbonates and any hydroxide which may be present. The principle consists in titration of the total alkalinity with standard volumetric hydrochloric acid solution in the presence of methyl orange as indicator. Calculation of the three amounts a), b), and c). - Replaces ISO Recommendation R 990-1969.

Describes a method that is more sensitive and more widely used than the 2,2'-bipyridyl method. It is applicable to products having iron contents equal to or greater than 0.3 mg/kg. The principle is based on the reduction of iron(III) by hydroxylammonium chloride, formation of a iron(II)/1,10-phenanthroline complex in a buffered system. Photometric measurement of the coloured complex at a wavelength of about 510 nm. - Cancels and replaces ISO Recommendation R 994-1969.