Rechercher

Applicable to the determination of Fe contents, expressed as Fe2 O3 , of more than 0.020 % (m/m). Covers the dissolution of a test portion by alkaline fusion by means of sodium carbonate and boric acid. Dissolving of the residue with nitric acid solution and reduction of iron(III) by means of hydroxylammonium chloride. Formation of the iron(II)-1,10-phenanthroline complex in a buffered medium at…

Applicable to products having H2 SiF6 contents between 0.01 % (m/m) and 0.2 % (m/m). Gives introductory instructions to the risk in handling with the product. The principle of analysis consists in formation of oxidized molybdosilicate (yellow) in weakly acid medium in the presence of boric acid to suppress interference by fluorine. Selective reduction of this complex after addition of sulphuric…

Preliminary reduction of the iron(III) by hydroxylammonium chloride, if required, suppression of the interference of tin by oxalic acid. Formation of the coloured iron(III)-2,2'-dipyridyl complex in a buffered medium. Photometric measurement of the coloured complex at a wavelength of about 522 nm.

Applicable to products in which the content of soluble iron exceeds 2 mg/kg. The preparation of the test solution is carried out according to ISO 2217. Reduction of the iron(III), contained in the aliquot part of the solution, with hydroxylammonium chloride. Formation of the coloured complex between iron(II) and 2,2'-dipyridyl in buffered solution. Photometric measurement of the coloured…

Is applicable to products having a minimum KCl content of about 95 % (m/m). The principle consists in dissolution of a test portion taken from the laboratory sample, previously ground and sifted. Acidification to pH 1 after suitable dilution, and atomization of the resultant solution in the burner of a flame spectrophotometer. Measurement of the intensity of the 766 nm ray, compared with the…

The method is applicable to products having a minimum KCL content of about 95 % (m/m). The principle consists in dissolution of a test portion taken from the laboratory sample, previously ground and sifted. Addition of formaldehyde solution to transform any ammonium ions present into hexamethylenetetramine, and of ethylenedinitrilotetraacetic acid, disodium salt, to complex any extraneous cations…

The method is applicable to products having a minimum KCl content of about 95 % (m/m). The principle consists in dissolution of a test portion taken from the previously ground and sifted laboratory sample and elimination of many ammonium ions present. Precipitation of the potassium, in a slightly acid medium, by an excess of an standard volumetric sodium tetraphenylborate solution. Filtration and…

The solubility of wool in alkali provides a useful index of the extent of change in its chemical properties brought about by certain agencies. Immersion of the wool in sodium hydroxide solution under specified conditions of time, temperature and volume. Determination of the loss in mass as the difference in the mass of the dry sample before and after treatment.

Application to products containing at least 98 % of elemental sulphur, expressed as a percentage by mass, of the product dried at 80 °C for 2 h. The difference between the ash and the residue corresponds to the "non-volatile bituminous matter" content at 200 °C. The principle of ashing consists in slow combustion in air of a test portion of the dried product. Heating in a furnace,…

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…