Vivaspin® concentrators are disposable ultrafiltration devices for the concentration of biological samples. Vivaspin® 2 can effectively be used in swing bucket or fixed angle rotors accepting 15 ml centrifuge tubes. The patented vertical membrane design and thin channel filtration chamber (US 5,647,990) minimizes membrane fouling and provides high speed concentrations, even with particle-laden solutions. Vivaspin® 2 combines the speed of the classic Vivaspin® products with low internal surface and membrane area in order to achieve superior recoveries from very dilute solutions. Available with a choice of PES, Cellulose Triacetate or Hydrosart® membranes, Vivaspin® 2 offers the highest flexibility for process optimization. Another unique feature of Vivaspin® 2 is the choice of directly pipetting the concentrate from the dead stop pocket built into the bottom of the concentrator or alternatively reverse-spinning the concentrate into the recovery cap. Both methods result in near total concentrate recovery.