Details

The storage conditions and stability of PBS (phosphate buffered saline) prepared in the laboratory mainly depend on whether it is sterilized and whether it contains additives, as follows:

1.Sterilized PBS (without additives such as serum, antibiotics, etc.)

>Storage temperature

A:Short-term storage (within several weeks) : Refrigerate at 4 ° C (in a sealed container) to prevent microbial contamination and component leaching.

B:Long-term storage (several months) : Freeze at -20℃ (it is recommended to aliquot to avoid repeated freezing and thawing), but note: Freezing may cause slight precipitation of phosphate. After thawing, gently shake well. If there is insoluble precipitate, re-prepare.

C:Storage at room temperature: If well sealed and away from light, it can be stored for 1-2 weeks for a short period of time. However, be vigilant against environmental microbial contamination (especially in humid environments), and high temperatures may accelerate the decline in buffering capacity.

>Stability

Sterilized PBS can usually remain stable for 3 to 6 months when stored in a sealed container at 4℃. If turbidity, sedimentation, unpleasant odor or significant pH change occurs (which can be detected by pH test paper), it should be discarded and not reused.

2. Unsterilized PBS (for non-sterile experiments only, such as general washing, sample dilution, etc.)

Storage temperature: Must be refrigerated at 4℃ (to inhibit microbial growth), do not store at room temperature.

Stability: Usually, it can only be stored for 1-2 weeks. It is necessary to closely observe whether it becomes turbid (caused by microbial reproduction). Once it becomes turbid, it will lose its effectiveness.

Notes

Storage containers should be clean and well-sealed (such as sterilized glass bottles or centrifuge tubes), avoiding evaporation, contamination or excessive contact with air (to prevent CO₂ from entering and affecting pH).

If calcium and magnesium ions (such as "PBS++") are added to PBS, long-term storage may cause turbidity due to ion precipitation. It is recommended to shorten the storage time (1-2 months at 4℃) and shake well for observation before use.

No matter which storage method is used, the appearance should be checked before use: clarity, no sediment and no odor are the basic standards for qualification.