This document specifies a qualitative and quantitative procedure to determine the composition of animal hair fibre blends (made of wool, cashmere, yak, alpaca, camel or angora) by LC-MS without protein reduction. NOTE 1 – The composition of non-animal hair fibres can be measured by ISO 1833 (all parts). Both results are combined to determine the total fibre composition. The method is based on a preliminary identification, by light microscopy, of all fibres in the blend on the basis of their morphology, according to ISO/TR 11827[4]. It is not applicable if fibres of the same animal species (such as blends of cashmere and mohair) are present. NOTE 2 – In this case, the quantitative analysis is performed using microscopical analysis [for example, ISO 17751 (all parts)].