Sodium sulphate for industrial use — Determination of iron content — 1,10- Phenanthroline photometri...
Applicable to products the Fe content of which is equal to or more than 0.0003 % (m/m). Dissolution of the test sample in delute hydrochloric acid and bromine water by heating. Preliminary reduction of the iron(III) by hydroxylammonium chloride. Formation of the iron(II)-1,10-phenanthroline complex in a buffered medium. Photometric measurement of the coloured complex at a wavelength of about 510…
Cheese — Determination of fat content — Butyrometer for Van Gulik method
Specifies the characteristics of an apparatus with a measuring range between 0 and 40 % and illustrates suitable devices for weighing and introducing the cheese test portion. Describes the scale, its graduation and the inscriptions to be marked on the body of the butyrometer. In addition, it gives information on material, shape and dimensions of stoppers for butyrometers.
Cheese — Determination of fat content — Van Gulik method
Applicable to all types of cheese. The principle of determination consists in dissolving the protein with sulphuric acid, followed by separation of the cheese fat in a Van Gulik butyrometer by centrifugating, the separation being assisted by addition of a small quality of amyl alcohol. The fat content is read directly on butyrometer scale.
Nitric acid for industrial use — Determination of sulphate content — Method by reduction and titrime...
Applicable to products the SO4 content of which is equal to or more than 0.0001 % (m/m). Heating of a test portion to dryness in the presence of sodium carbonate. Reduction of the sulphureous residue to sulphides by a mixture of hydriodic acid and hypophosphorus acid. Absorption of the hydrogen sulphide evolved in a mixture of sodium hydroxide solution and acetone. Titration with standard…
Ammonium nitrate for industrial use — Determination of content of sulphur compounds — Method by redu...
Applicable to products the content of which, expressed as sulphate, is equal to or more than 0.0005 % (m/m). Heating of a test portion in the presence of sodium carbonate, in a fume-cupboard, until the ammonium salts have been eliminated (about 300 °C). Reduction of the sulphureous residue to sulphides by a mixture of hydriodic acid and hypophosphorus acid. Absorption of the hydrogen sulphide…
Ammonium nitrate for industrial use — Determination of ammoniacal nitrogen content — Titrimetric met...
Based on dissolution of a test sample in water. Distillation of the ammonia after displacement by an alkali solution. Absorption in an excess of standard volumetric sulphuric acid solution and back-titration with standard volumetric sodium hydroxide solution in the presence of methyl red/methylene blue mixed indicator. A typical distillation apparatus is shown in a figure.
Ammonium nitrate for industrial use — Determination of total nitrogen content — Titrimetric method a...
Based on the conversion of nitrate into ammonia by means of Devarda's alloy in alkaline solution together with the liberation of ammonia from ammonium ions. Distillation of the ammonia from both reactions, absorption in an excess of standard volumetric sodium hydroxide solution in the presence of methyl red/methylene blue mixed indicator. A typical distillation apparatus is shown in a figure.
Ammonium sulphate for industrial use — Determination of copper content — Zinc dibenzyldithiocarbamat...
Applicable to products of which the Cu content is more than 0,1 mg/kg. The detection bases on the formation of a coloured complex of copper and of zinc dibenzyldithiocarbamate and photometric measurement at a wavelength of about 435 nm.
Phosphoric acid for industrial use — Determination of soluble silica content — Reduced molybdosilica...
Specifies a reduced molybdosilicate spectrophotometric method for the determination of the soluble silica content of phosphoric acid for industrial use. The method can be used for the determination of 1 µg of soluble silica in the presence of 20 mg of phosphorus pentoxide. It is thus, for example, applicable to the determination of soluble silica contents greater than 30 mg/kg if the phosphoric…
