Meat and meat products — Determination of nitrate content (Reference method)
The method consists in extracting of a test portion with hot water, precipitating of proteins and filtrating. Reduction of the extracted nitrates into nitrites by metallic cadmium. Formation of a red colouration by adding of sulfanilamide and nphthyl ethylenediamine hydrochloride and photometric measurement at a wavelength of 538 nm.
Sodium tripolyphosphate and sodium pyrophosphate for industrial use — Determination of total phospho...
Based on hydrolysis of a test portion by prolonged boiling in the presence of hydrochloric acid. Precipitation of the phosphate ions in the form of quinoline phosphomolybdate in the presence of acetone. Filtration by means of a filter crucible, washing, drying and weighing of the precipitate.
Meat and meat products — Determination of nitrite content (Reference method)
The method consists in extracting of a test portion with hot water, precipitating of proteine and filtrating. In presence of nitrits formation of a red cloured complex by adding sulfanilamide and naphthylethylenediamine hydrochloride, and photometric measurement at a wavelength of 538 nm.
Phosphoric acid for industrial use — Determination of arsenic content — Silver diethyldithiocarbamat...
Applicable to products having As contents of more than 0.1 mg/kg. Relates to the method of analysis according to ISO 2590. Reduction of the As by zinc in a hydrochloric acid solution with the formation of arsine. Absorption of the arsine in a solution of silver diethyldithiocarbamate in pyridine. Photometric measurement of the purplish-red colour produced by the colloidally dispersed silver at…
Sodium hydroxide for industrial use — Determination of sulphur compounds — Method by reduction and t...
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…
Potassium hydroxide for industrial use — Determination of sulphur compounds — Method by reduction an...
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…
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.
