Amicon® Ultra-2 mL centrifugal filter devices provide fast ultrafiltration, with the capability for high concentration factors and easy concentrate recovery from dilute and complex sample matrices. The vertical design and available membrane surface area provide fast sample processing, high sample recovery (typically greater than 90% of dilute starting solution), and the capability for 50-fold concentration. Solute polarization and subsequent fouling of the membrane are minimized by the vertical design, and a physical deadstop in the filter device prevents spinning to dryness and potential sample loss. Efficient recovery of the concentrated sample (retained species) is achieved by a convenient reverse spin step after collecting the filtrate. The device can be spun in a swinging bucket or fixed angle rotor. Amicon® Ultra-2 mL devices are supplied non-sterile and are for single use only. With their vertical membrane design and reverse spin, Amicon® Ultra 2 mL filters deliver the highest recovery with shortest spin times.