Plastics - Phenol-formaldehyde mouldings - Determination of free ammonia and ammonium compounds - Colorimetric comparison method (ISO 120:1977)
Specification of a semi-quantitative method. The content of free ammonia in a moulded article is of importance, when corrosion of metal inserts or contamination in contact with the article has to be considered. Distillation of the aqueous extract from a powdered test portion, coloration of the distillate by reaction with Nessler reagent and comparison of the colour with that of standard matching solutions.
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