1. Fetal bovine serum is recommended to be stored in -20℃ to -80℃ medical refrigerator. When the serum is thawed, it should be transferred from -80℃ to -20℃ and then to 2-8℃ overnight. After the serum is basically thawed at 2-8℃, it should be transferred to room temperature (16-25℃) and thawed completely for storage or sealed frozen storage. In the process of thawing, the fetal bovine serum needs to be shaken regularly to make it evenly mixed, to avoid the aggregation of protein substances in the serum to cause flocs. After the serum is dissolved, if one bottle cannot be used at a time, the serum can be stored in a sterile, non-pyrogen container sealed and frozen.

2. The serum should not be directly transferred from -20℃ to room temperature and thawed in a warm bath at 37℃ or 56℃. Precipitation is easy to occur when the temperature difference is too large, and it is easy to make the serum become turbidized when placed at 37℃ for too long. At the same time, some of unstable components of the serum will be destroyed, which will affect the quality of the serum. If flocculent precipitation has been found after serum dissolution, it is suggested to remove the precipitation by centrifuging at 400g/1-2 minutes or simply depositing it on the bottom of the bottle, and carefully transfer the serum to a sterile bottle. Filtering is not recommended. After the serum is completely thawed, it can be placed at 37℃ to keep the mixture regularly shaken, the precipitation will disappear naturally, however, during the heating process of this method, the complement in fetal bovine serum may be destroyed.

3. Fetal bovine serum defrosted at 2-8℃ generally fails to be stored for about 3 weeks in an unopened and very clean refrigerated environment. It is recommended to prepare or seal and freeze the unsealed or packaged serum immediately, because fetal bovine serum will be stored in cold storage or room temperature for a long time, which will easily produce phage or other pollution sources, increase the endotoxin index of the serum, degrade the active components, and affect the use quality. Therefore, do not store fetal bovine serum in cold storage at 2-8℃ or at room temperature for a long time.