Preparation of 1 mM Biotin Stock Solution in PBS


Biotin (also known as vitamin B7) is slightly soluble in water but soluble in hot and alkaline water. A 1 mM Biotin stock solution can be prepared by dissolving 2.44 mg of Biotin in PBS to a final volume of 10 ml.


Reagents and solutions
Biotin (C10H16N2O3S, Molecular Weight 244.31)
Deionized water

Equipment and disposables
15 ml graduated screw-capped centrifuge tube
Vortexer mixer or Tube Rotator

1 mM Biotin


Step 1: To prepare 10 ml of 1 mM biotin stock solution, weigh out 2.44 mg Biotin and transfer it to a 15 ml graduated screw-capped centrifuge tube. Add 9 ml PBS and mix by vortexing the tube or by keeping it on the tube rotator to dissolve it.

You can add a few drops of 1N NaOH to dissolve the Biotin.

Do not dissolve in 10 ml of deionized / Milli-Q water. Volume of the solution will increase when you add a few drops of 1N NaOH to dissolve biotin.

Step 2: Adjust the volume to 10 ml with deionized water. Mix it again.

Step 3: Sterilize the solution by filtering through a syringe filter unit containing a membrane with pore size 0.22 μm or less under aseptic condition.

Aseptically aliquoted the solution into smaller volumes (0.5 ml or 1 ml)  and stored at -20°C until use.

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