ISO 1833-12:2019

This document specifies a method, using dimethylformamide, to determine the mass percentage of acrylic, modacrylic, chlorofibre or elastane, after removal of non-fibrous matter, in textiles made of mixtures of
-  acrylic, certain modacrylics, certain chlorofibres, certain elastane fibres
with
-  wool, animal hair, silk, cotton, viscose, cupro, modal, lyocell, polyamide, polyester, elastomultiester, elastolefin, melamine, polyacrylate or glass fibres.
It is not applicable to animal hair, wool and silk dyed with chromium based mordant dyes.
NOTE       Dyestuff identification is described in ISO 16373-1[3].