Certain proteins, particularly when dilute, tend to show a high affinity towards various surfaces which may lead to irreversible binding. Although Pall centrifugal devices are made of materials with low intrinsic affinity for proteins, this phenomenon can cause decreased recovery. Protein recovery can be improved through 'passivation' of the device. This is a pretreatment aimed to occupy potential binding sites by filtering a solution with additional protein (often albumin), detergents, or salts through the centrifugal device prior to use.