Fuente: WIPO "biotechnology" Problem: when proteins are purified using a protein-binding dye immobilised on a chromatographic matrix, the dye or a portion/derivative may leak into the eluant. Solution: an ion-exchange resin (e.g. Dowex-1) and a disrupting material (e.g. salt and a fatty acid such as sodium octanoate) are used to separate the dye from the protein.