This document specifies a method, using dichloromethane, to determine the mass percentage of triacetate or polylactide, after removal of non-fibrous matter, in textiles made of mixtures of — triacetate or polylactide with — wool or other animal hair, silk, protein, cotton, viscose, cupro, modal,lyocell, polyamide, polyester, acrylic, elastomultiester, polypropylene, elastolefin, melamine, polypropylene/polyamide bicomponent,polyacrylate and glass fibres.