Ammonium nitrate for industrial use — Determination of free acidity — Volumetric method
The principle of the analysis consists in titration of a test portion with a standard sodium hydroxide solution in the presence of methyl red/methylene blue mixed indicator.
Aluminium fluoride for industrial use — Determination of fluorine content — Modified Willard-Winter ...
The principle of the method consists in fusion of a test portion with sodium carbonate. Separation of fluorine by distillation with sulphuric acid. Titration with thorium nitrate solution using sodium alizarinsulphonate-methylene blue as indicator. Alternatively, the thorium nitrate titration may be made using only sodium alizarinsulphonate; the end-point being spectrophotometrically determined…
Formaldehyde solutions for industrial use — Limit test for inorganic chlorides
The method, as specified, is applicable when the required limit is not greater than 0,05 % and not less than 0,0005 %. If the required limit lies outside that range, the mass of the test portion should be changed. The principle of the test consists in comparison of the turbidity obtained by the addition of silver nitrate solution to a solution of the sample, in the presence of nitric acid, with…
Formaldehyde solutions for industrial use — Limit test for inorganic sulphates
The specified method is applicable when the required limit is not greater than 0,1 % and not less than 0,001 %. If the required limit lies outside that range, the mass of the test portion should be changed. The principle ot the test consists in comparison of the turbidity obtained by the addition of barium chloride solution to a solution of the sample, in the presence of hydrochloric acid, with…
Formaldehyde solutions for industrial use — Determination of iron content — 2,2'- Bipyridyl pho...
The specified method is applicable to the detection of Fe contents less than 0,0004 % (m/m). The principle consists in conversion of any iron present into the sulphate by evaporation to dryness in the presence of sulphuric acid, and reduction of iron (III) by means of hydroxylammonium chloride. Formation of a iron (II) 2,2'-bipyridyl complex. Photometric measurement of the coloured complex…
Formaldehyde solutions for industrial use — Determination of formaldehyde content
The specified method is applicable to HCHO contents between 25 5 and 45 %. The field of application may be extended by siutably modifying the mass of the test portion. The principle consists in the reaction of the test solution with a neutral sodium sulphite solution, and acidimetric titration of the liberated sodium hydroxide in presence of thymolphthalein as indicator.
Formaldehyde solutions for industrial use — Determination of methanol content
The results obtained by this method will include the methanol freed from combined forms. These are however not usually present at higher levels to effect the results. The principle consists in esterfication of the methanol present with formic acid using sulphuric acid as a catalyst. Distillation of the methyl formate into sodium hydroxide solution and back-titration of the excess sodium hydroxide…
Formaldehyde solutions for industrial use — Limit test for heavy metals (excluding iron)
The method detects only the heavy metals present in non-complex form, the sulphides of which are precipitated in acid solution. The method is not specific for any one heavy metal. The principle consists in conversion of heavy metal, such as lead and copper, in acid solution to their sulphides, and comparison of the colour produced with that given by an aliquot volume of standard lead solution…
