Handling and Aliquoting Frozen Stock of L-glutamine

Ready to use L-glutamine solution (200 mM, sterile-filtered, 100 x concentration) is commercially supplied in different sizes with 100 ml being the most common size. Since repeated freezing and thawing of L-glutamine can cause degradation, it is recommended to store L-glutamine in small aliquots that can be consumed completely upon thawing. Since the culture medium is often prepared in 500 ml sizes that require 5 ml L-glutamine, preparing 5 ml aliquots is a good choice. You can prepare 20 aliquots of 5 ml with 100 ml stock solution.


Reagents and solution
♦ L-Glutamine stock solution

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

Prior to start:
♦ Label twenty sterile 15-ml tubes with 100X L-Glutamine (200 mM), date, Catalog no., and company name. 
♦ Set the water bath at 37°C


Step 1: Thaw the L-Glutamine solution by keeping it in a 37°C water bath.
You will see white precipitate in the bottle. You must shake the bottle to dissolve it. This will also accelerate the thawing process.

Precaution: As soon as all solution is thawed, remove the bottle from the water bath and start aliquoting it. The L-Glutamine solution must be stored in frozen form to protect it from degradation.

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 5 ml in each tube using pipette and pipette aid.
Before aliquoting, mix the content by inverting the bottle 3-4 times.

Precaution: Never pour the solution in a tube.

Store all aliquots at -20°C.

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