Sodium sulphate for industrial use — Determination of chlorides content — Mercurimetric method
Applicable to products the content of which expressed as chlorine exceeds 0.005 % (m/m). If the analyst can easily detect the indicator's colour change using a 0.02 N standard volumetric mercury(II) nitrate solution the method can, subjected to agreement, be extended to products the content of which exceeds 0.001 % (m/m). The titration of the chloride ions (Cl- ) is carried out with a 0.1 N…
Sodium sulphate for industrial use — Determination of sulphates content — Calculation method and bar...
Applicable to the analysis of products manufactured by traditional methods provided that the impurities other than sulphates are well known. The gravimetric method shall be applied only in the case of doubt as to the accuracy of the calculated result. Principle of calculation: subtraction of the loss in mass at 110 °C, acid-insoluble matter, chlorides content (as NaCl), alkalinity (as Na2 CO3 )…
Sodium sulphate for industrial use — Determination of calcium content — EDTA complexometric method
Applicable to products the Ca content of which exceeds 0.002 % (m/m). Extraction of a test portion with dilute acid and separation of the insoluble residue. Titration of the calcium with standard volumetric disodium ethylenediamine-NNN'N'-tetra-acetate dihydrate (EDTA) solution in the presence of glyoxal-bis(hydoxy-2-anil) as indicator.
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.
