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