The Tris/Borate/EDTA buffer (TBE) is commonly made as a 5x solution. What volumes of 5x TBE and water are required to make 500 mls of a 0.5x solution which is often used in electrophoresis?

50 ml (5x TBE) + 540 ml (water)

Explanation:

To prepare 0.5x TBE solution from 5x TBE solution we need to use the following dilution formula:

C1 x V1 = C2 x V2, where:

- C1, V1 = Concentration/amount (start), and Volume (start)

- C2, V2 = Concentration/amount (final), and Volume (final)

* So when we applied this formula it will be:

5 x V1 = 0.5 x 500

V1 = 50ml

- To prepare 0.5x we will take 50ml from 5x and completed with 450ml water and the final volume will going to be 500ml.