Important processes and parameters that affect the recovery yield using tangential flow ultrafiltration for the concentration and purification of proteins from dilute, large volume samples are investigated. Proteins from a radiolabeled E. coli cell lysate are concentrated from 60 and 20 L samples of artificial seawater. First, the improvement in the recovery and carryover with use of surface blocking agents is measured. The surface passivation resulted in a measurable decrease in adsorptive losses with minimal carryover. Additionally, the surface blocking agent pre-treatment resulted in more reproducible and reliable recovery yields (similar to 55-60%) and enhanced initial relative recovery by 46% for the initial 20 L processed. Second, the effects of the total protein sample concentration on the recovery yield are investigated. At low protein concentration (1.0 mu g protein/L) the percent recovery yield was reduced, while at concentrations above 2.0 mu g protein/L the percent recovery yield was nearly constant. Third, the components of the system were quantitatively analyzed to identify the relative contribution of the system components to adsorptive loss, and no single component was found to account for a large percent of the adsorptive loss. These results provide quantitative values for the recovery yields and critical information for improving protein recovery. (c) 2005 Elsevier B.V. All rights reserved.