ISO 1833-17:2019

This document specifies a method, using concentrated sulfuric acid, to determine the mass percentage of chlorofibres and certain other fibres, after removal of non-fibrous material, in textiles made of mixtures of
-  cotton, viscose, cupro, modal, lyocell, acetate, triacetate, polyamide, polyester, elastomultiester, certain acrylic and certain modacrylic fibres
with
-  chlorofibres (based on homopolymers of vinyl chloride), polypropylene, elastolefin, melamine and polypropylene/polyamide bicomponent.
The modacrylics concerned are those which give a clear solution when immersed in concentrated sulfuric acid.
This method can be used, particularly in place of the methods described in ISO 1833-12 and ISO 1833-13, in all cases where a preliminary test shows that the chlorofibres do not dissolve completely either in dimethylformamide or in the azeotropic mixture of carbon disulfide and acetone.