Sodium hydroxide for industrial use — Determination of silica content — Reduced silico-molybdic comp...
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…
Cryolite, natural and artificial — Determination of sodium content — Flame emission and atomic absor...
The methods are applicable as alternatives to products for which the molar ratio NaF/AlF3 is equal to about 3. The principle of the flame emission method consists in atomization of the test solution in a flame of oxygen/hydrogen and determination by measurement of the intensity of the radiation at 589 nm. The principle of the flame atomic absorption method is based on atomization in an air/…
Glycerols for industrial use — Determination of arsenic content — Silver diethyldithiocarbamate phot...
The method is applicable tp products with a content greater than 0,1 mg/kg. It is applied to a test portion as it is, and to another identical portion with a known quantity of arsenic added. The principle consists in reduction of the arsenic by zinc in a hydrochloric acid medium, with the formation of arsine; absorption of the arsine in a solution of silver diethyldithiocarbamate in pyridine.…
Sulphuric acid and oleums for industrial use — Determination of ammoniacal nitrogen content — Spectr...
Applicable to products having contents of more than 0.0001 % (m/m). The procedure described is suitable for contents between 0.0001 % (m/m) and 0.0005 % (m/m). It bases on distillation, with entrainment by steam, of the ammonia in the presence of an excess of sodium hydroxide and collection of the distillate in an excess of acid solution. Neutralization of the dexcess of acid and formation of the…
Nitric acid for industrial use — Determination of ammoniacal nitrogen content — Spectrophotometric m...
Applicable to products containing more than 0.0001 % (m/m) of ammoniacal nitrogen. The procedure described is siutable for contents between 0.0001 % (m/m) and 0.0005 % (m/m). The principle of the analysis consists in distillation, with entrainment by steam, of the ammonia in the presence of an excess of sodium hydroxide and collection of the distillate in an excess of acid solution.…
Ammonium sulphate for industrial use — Determination of iron content — 2,2'- Bipyridyl photomet...
Applicable to Fe contents of equal to or more than 0.0001 % (m/m). The reaction bases on the reduction of iron(III) by hydroxylammonium chloride. Formation of the complex between iron(II) and 2,2'-dipyridyl in a buffered medium (pH value between 4.5 and 6). Photometric measurement of the coloured complex at a wavelength of about 522 nm. Has also been approved by the IUPAC.
Paints and varnishes — Determination of viscosity at a high rate of shear
Describes a procedure for determining the viscosity of coating materials and related products at a rate of shear not less than 5000 s-1 and not higher than 20000 s-1. When products are being compared the rate of shear shall be approximately the same. The test shall be made at a closely controlled temperature unless otherwise agreed. The value obtained gives information about the resistance of the…
Sulphuric acid and oleum for industrial use — Determination of lead content — Dithizone photometric ...
Applicable to the determination of contents exceeding 1 mg/kg. The principle bases on evaporation of the test portion, dissolution in hydrochloric acid and reduction by hydroxylammonium chloride. Formation of complexes of interferring elements with ammonium citrate and potassium cyanide. Extraction of the lead at a pH of between 8.5 and 10 by a solution of dithizone in chloroform. Elimination of…
Urea for industrial use — Determination of biuret content — Photometric method
Applicable to the determination in the presence of ammoniacal salts less than 15 mg in the aliquot amount taken for the determination. In the presence of quantities exceeding 15 mg the ammoniacal nitrogen shall be removed by a cation exchange resin because these salts interfere with the determination. The principle of the reaction consists in formation of a violet-red complex between allophanic…
