Maintenance and use method of ultrafiltration tube

Maintenance and use method of ultrafiltration tube

Function of ultrafiltration tube:

1) Concentration; 2) Desalting; 3) Replace buffer; 4) It has the effect of partial purification.

1. The new ultrafiltration tube can be used directly without other treatment;

2. The ultrafiltration tube cannot be sterilized at high temperature;

3. Treatment of ultrafiltration tube when changing concentrated protein

The ultrafiltration tube can be reused. Soak it in 0.1M NaOH for 1-2h, wash it with water, and then wash it with relevant solution (sterilized water or PBS) on the centrifuge for 3 times, which can be used to concentrate new protein;

4. Treatment of normally placed ultrafiltration tube

For the frequently used ultrafiltration tube, soak it in 0.1M NaOH for 1-2h, wash it with water and soak it in sterilized water. Be sure to keep the filter membrane wet and prevent bacteria from growing;

5. Treatment of ultrafiltration tube placed for a long time

If the ultrafiltration tube is not used for a long time, soak it in 0.1M NaOH for 1-2h, wash it with water, and soak it in 20% ethanol for storage. Be sure to keep the filter membrane wet and prevent bacteria from growing;

6. Centrifugal speed used for ultrafiltration tube

The centrifugal speed is generally 4000rpm (3000g is generally recommended, and the maximum can not exceed 4000g). After centrifugation for 5-8 minutes, 4ml sample can be concentrated to less than 1ml to dozens of microliters; If the speed is too high, the target protein will fall off, resulting in the loss of target protein; Low speed, time-consuming and low work efficiency;

7. Precautions when the gun head extends into the ultrafiltration tube

When adding protein solution or buffer to the ultrafiltration tube, the blue gun head can be used; However, when the concentrated target protein is absorbed from the bottom of the ultrafiltration tube, the yellow gun head must be used; When the gun head is inserted into the ultrafiltration tube, it must be prevented from touching the filter membrane to avoid puncturing the filter membrane;

8. Reduce protein adsorption loss of ultrafiltration tube

The membrane of the ultrafiltration tube can adsorb protein, which will reduce the target protein by about 30%; In order to reduce protein loss, after absorbing the target protein solution, purge the bottom of the ultrafiltration tube with protein buffer to wash most of the protein adsorbed by the filter membrane and reduce the loss of target protein; If the purified protein is concentrated, pay attention that the concentrated volume should not be too small; Generally, no matter how centrifuged, about 200 µ L protein solution will be retained at the bottom;

9. How to define the failure of ultrafiltration tube

Under normal use, when the filter membrane is not punctured, the concentrated protein solution does not contain protein or the amount is very low (including target protein), while the first filtered solution contains target protein, it indicates that the filter membrane is invalid and needs to be replaced with a new ultrafiltration tube.