For proteins and other biological samples such as nucleic acids with 3K and 5K MWCO, Pierce Protein Enrichment Tubes (PES) provide rapid protein concentration, excellent sample recovery and instrument compatibility. These centrifugal devices feature high-throughput polyethersulfone (PES) membranes and are suitable for concentration, desalting and buffer exchange of biological samples. These concentrator tubes are available in MWCO 3K and 5K and can be used to handle sample volumes from 0.5–100 mL.

Features of the 3K and 5K MWCO Protein Concentrators (PES) include:
•Fast Protein Concentration—Concentrate samples from 10 to 10 to 15 minutes in 15 minutes or less 30x
• Excellent protein recovery—Typical protein recovery >90% (when sample mass is at least two times greater than claimed MWCO)
• Instrument Compatible Robust—Standard microcentrifuges with horizontal baskets or fixed-angle (except 88534) rotors can be used; no counter-rotation is required to collect and recover samples
• Versatile—Easy bioprocessing Concentration, diafiltration or buffer exchange of samples

For easy identification, the MWCO value is etched on the side of each tube. To facilitate sample addition and recovery, each tube has a graduated transparent window on the side for visual determination of the trapped volume. The vertical design of the membrane enables high throughput rates, low non-specific binding and negligible protein aggregation on the membrane, and provides reliable and consistent results for processing sample volumes of 0.5-100 mL. Typical protein recoveries are 90% when the mass of protein in the sample is at least twice the MWCO of the device used. For example, when concentrating IgG (MW ∼150 KDa) samples, use 5K, 10K, 30K, or 50K MWCO concentrator tubes. Samples can be ultimately concentrated 10 to 30 times in 15 minutes or less.

Protein Enrichment Tubes (PES) Applications
• Protein concentration of tissue culture media, antisera or monoclonal antibody preparations
• After processing by gel permeation chromatography Concentration of peaked proteins
• Removal of unbound label after protein modification reaction
• Elution from ion exchange, hydrophobic interaction (HIC), metal chelate or affinity columns Concentration, desalting/buffer exchange of proteins that have come down
• Separation of molecules of different sizes

Pierce Protein Enrichment Tube (PES) contains a membrane for trapping molecules with a molecular weight of at least the device The MWCO of the inner PES membrane is twice the stated value. Using concentrator tubes with a molecular weight smaller than recommended may reduce recovery. Protein recovery will vary depending on the specific protein in the sample and its starting concentration.

The stop volumes for the 0.5 mL, 2–6 mL, 5–20 mL, and 20–100 mL concentrator tubes are approximately 15 µL, 30 µL, 50 µL, and 350 µL, respectively.

To achieve >90% protein recovery using 0.5 mL concentrator tubes, the protein sample concentration should be at least 0.05 mg/mL. For all other concentrator tubes, the protein sample concentration should be no less than 0.1 mg/mL.

Excellent centrifugation and speed
Efficient use of 0.5 mL concentrator tubes at maximum centrifugal force of 15,000 × g using only a fixed-angle centrifuge.

For 2-6 mL concentrator tubes, horizontal basket or fixed angle centrifuge models are available. Horizontal basket centrifuges are capable of producing a centrifugal force of 2,000–4,000 × g, with a maximum recommended centrifugal force of 4,000 × g. For fixed-angle centrifuges, models are capable of generating centrifugal forces of 5,000–10,000 × g, with a maximum recommended centrifugal force of 8,000 × g.

For concentrator tubes with volumes of 5-20 mL, horizontal basket or fixed angle centrifuge models are available. Horizontal basket centrifuges are capable of producing a centrifugal force of 2,000–5,000 × g, with a maximum recommended centrifugal force of 4,000 × g. For fixed-angle centrifuges, models are capable of generating centrifugal forces of 5,000–8,000 × g, with a maximum recommended centrifugal force of 6,000 × g.

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

Centrifugal force, temperature and sample volume, concentration and viscosity will affect filtration rate, requiring optimization of time for each application.