For protein and other biological samples, such as nucleic acids with a 50K MWCO, Thermo Scientific Pierce Protein Concentrators PES offer rapid protein concentration, excellent sample recovery, and instrument compatibility. These centrifugal devices feature a high-flux polyethersulfone (PES) membrane for concentration, desalting, and buffer exchange of biological samples. This product has a molecular-weight cutoff of 50K and can be used for processing sample volumes of 0.5–100 mL.

Features of 50K MWCO Protein Concentrators PES include:
• Rapid protein concentration—sample concentration of 10- to 30-fold can be achieved in 15 or fewer minutes
• Excellent protein recovery—typical protein recovery is >90% (when the sample mass is at least two-fold greater than the posted MWCO)
• Instrument-compatibility—a standard microcentrifuge with swinging (except 88504) or fixed-angle rotors can be used; sample can be collected and recovered without invert spinning
• Versatile—easily perform sample concentration, diafiltration, or buffer-exchange of biological samples

For easy identification, the MWCO value is etched on the side of each device. To assist with sample addition and recovery, a clear window with graduations is located on the side of each device enabling visual determination of the retentate volume. The vertical design of the membrane allows high-flux rates, low non-specific binding, and negligible protein aggregation on the membrane and provides reliable and consistent results for processing sample volumes between 0.5 and 100 mL. Typical protein recovery is 90% when the mass of the proteins in the sample is at least two-fold greater than the MWCO of the device used. For example, when using IgG (MW ~150K) samples, use the 5K, 10K, 30K, or 50K MWCO Concentrators. Sample concentration of 10- to 30-fold can be achieved within 15 minutes.

Protein Concentrators PES applications
• Protein concentration of tissue culture media, antiserum, or monoclonal antibody preparations
• Concentration of protein peaks following gel-permeation chromatography
• Removal of unincorporated label following protein modification reactions
• Concentration and desalt/buffer-exchange after elution of protein from ion-exchange, hydrophobic interaction (HIC), metal chelate, or affinity chromatography columns
• Separation of different sized molecules

Pierce Protein Concentrators PES contain a membrane rated for retaining molecules with a molecular weight at least two-fold greater than the MWCO rating of the PES membrane within the device. Reduced recovery may occur when using a concentrator with molecules smaller than the recommended mass. Protein recovery will vary depending on the specific protein in the sample and its starting concentration.

The dead-stop volume for the 0.5 mL, 2–6 mL, 5–20 mL, and 20–100 mL concentrators is approximately 15 µL, 30 µL, 50 µL, and 350 µL, respectively.

To achieve >90% recovery of protein with the 0.5 mL concentrators, the minimum protein sample concentration should be 0.05 mg/mL. For all other concentrators, the minimum protein sample concentration should be 0.1 mg/mL.

Optimal centrifuges and speeds
The 0.5 mL concentrators can be used effectively at a maximum centrifugal force of 15,000 × g using a fixed angle centrifuge only.

For the 2-6 mL concentrators, swinging-bucket or fixed-angle centrifuge models can be used. Swinging bucket centrifuges capable of generating 2,000–4,000 × g and a maximum centrifugal force of 4,000 × g are recommended. With fixed-angle centrifuges, models capable of generating 5,000–10,000 × g and a maximum centrifugal force of 8,000 × g are recommended.

For the 5-20 mL volume concentrators, swinging-bucket or fixed-angle centrifuge models can be used. Swinging-bucket centrifuges capable of generating 2,000–5,000 × g and a maximum centrifugal force of 4,000 × g are recommended. With fixed-angle centrifuges, models capable of generating 5,000–8,000 × g and a maximum centrifugal force of 6,000 × g are recommended.

For the 20-100 mL concentrators, only swinging-bucket centrifuges capable of generating 1,000–2,000 × g are recommended. Use a maximum centrifugal force of 2,000 × g. These concentrators are not recommended for use in fixed-angle rotors.

Centrifugal force, temperature, sample volume, concentration, and viscosity will all affect filtration rate. Centrifugation time should therefore be optimized for each application.