When choosing an appropriate ultrafiltration tube, the main considerations are MWCO and concentration volume. The most common one is Ultra-15 (10kD).
Usually, the molecular weight cutoff should not be greater than 1/3 of the molecular weight of the target protein. For example, if the molecular weight of the target protein is 35kDa, you can choose an ultrafiltration tube with a molecular weight cutoff of 10kDa. If the molecular weight of the target protein is about 10kD, an ultrafiltration tube with a molecular weight cutoff of 3kD can be used. Read the instruction manual carefully and note that ultrafiltration membranes have different tolerances to various chemicals.
The newly purchased ultrafiltration is dry. Before use, add MilliQ water to completely cover the membrane, and pre-cool it in an ice bath or refrigerator for a few minutes. Then pour out the water and add the protein solution. The amount added shall not exceed the white line at the top of the tube. The operation should be gentle. The ultrafiltration tube needs to be placed on ice to pre-cool before adding the protein solution.
Extended information:
Ultrafiltration concentration centrifuge tube, the latest patented product Hydrosart membrane type 2K has extremely low protein adsorption characteristics, high flow rate and high throughput. It is the ideal immunoglobulin Ideal membrane for protein concentration and desalting.
Ultrafiltration membranes are available in four materials: polyethersulfone, cellulose triacetate, regenerated cellulose and Hydrosart, which can be flexibly selected according to different requirements; two methods of recovering concentrated liquid: either a straw can be used Directly absorb and recover, or put the centrifuge tube into a centrifuge and spin it back, throw the concentrated liquid into the recovery cap, and cover it for storage. Both methods can achieve nearly complete recovery of the concentrated solution;
Baidu Encyclopedia - Ultrafiltration Concentration Centrifuge Tube