The invention relates to a method and a device for concentrating and stabilising conjugated oestrogens from the urine of pregnant mares on solid supports in order to obtain a suitable starting material for producing pharmaceuticals that contain the natural mixture of these conjugated oestrogens as the active component. The inventive device is characterised by its suitability for practical, decentralised concentration and stabilisation of mixtures of conjugated oestrogens (CE) contained in the urine (PMU) of pregnant mares on a solid support (= adsorbent), especially in the proximity of the stable or field, in a column or a cartridge. The adsorber columns can be filled directly at the site of urine collection with the device. As a result, it is no longer necessary to transport large quantities of urine liquid daily to a central processing point. The filling process can take place continuously over a longer period of up to several weeks, until the adsorber column or cartridge is saturated. The leftover urine that runs off remains at the site, where suitable devices for disposal are already available. Only the filled column or cartridge is transported and the transport can take place at longer intervals and take longer, e.g., up to a few weeks. The excellent stability of the CE on the adsorber ensures that there is no risk of decomposition.