Question

Given 200ul of a 0.5mg/ml stock solution of BSA, how much do you pipet into a test tube so that you are adding 5ug of BSA to the test tube

Answer 1

Answer: $10\mu L$ of volume needs to be pipetted out in the test tube.

Explanation:

We are given:

Mass of BSA to be formed = $5\mu g=0.005mg$      (Conversion factor: $1mg=1000\mu g$

Volume of stock solution = $200\mu L=0.2mL$    (Conversion factor: $1mL=1000\mu L$

It is also given that for the mass of BSA is 0.5 g, the volume used up is 1 mL

In order to have, 0.005 g, the volume of stock solution needed will be = $\frac{1mL}{0.5g}\times 0.005g=0.01mL=10\mu L$

Hence, $10\mu L$ of volume needs to be pipetted out in the test tube.