Handling and Aliquoting Frozen Stock of Serum

The serum is commercially supplied in different sizes with 500 ml being the most common size. Since repeated freezing and thawing of serum can compromise growth supportive activities of serum, it is recommended to store the serum in small aliquots that can be consumed completely upon thawing. Since the culture medium is often prepared in 500 ml sizes that require 50 ml serum, preparing 50 ml aliquots is a good choice. You can prepare 10 aliquots of 50 ml with a 500 ml stock solution.


Reagents and solution
♦ Serum (500 ml stock bottle)

Equipment and disposables
♦ Water bath
♦ 50 ml tubes
♦ Laminar flow hood (Class II)
♦ Pipette and pipette aid

Prior to start:
1. Label twenty sterile 50-ml tubes with Serum type (e.g., FBS), date, Catalog no. and supplier’s name. 
2. Set the water bath at 37°C


Step 1: Thaw the serum by keeping it in a 37°C water bath.

1. Shake the bottle frequently to accelerate the thawing process.
2. You can also leave the bottle overnight at 4°C for thawing.

Step 2: Wipe the bottle with dry tissue paper to remove water and then wipe with 70% ethanol and bring it inside the laminar flow hood.

Step 3: Aliquot 50 ml in each tube using 25 ml pipette and pipette aid.
Before aliquoting, mix the content by inverting the bottle 3-4 times.

Precaution: Pouring serum in 50 ml tubes from a serum bottle is not recommended as it can increase the risk of contamination.

Store all aliquots at -20°C.

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