Question

You are given a protein solution with a concentration of 0.15 mg/ml.

v. Suppose that we want to prepare 100 microliters of 0.1 micrograms/microliters solution. How much of H2O and protein stock do we need to add to obtain the target concentration and volume?

Answer 1

Step-by-step explanation:

The given data is as follows.

Initial concentration = 0.15 mg/ml,

Final concentration = 0.1 mg/ml, (as
`(0.1 microgram)/(1 microliter) * (10^(-3))/(1 microgram) * (1 microliter)/(10^(-3)ml)`)

Final volume =
`100 microliter * (10^(-3) ml)/(1 microliter)` = 0.1 ml

According to the dilution formula we get the following.

`C_(i) * V_(i) = C_(f) * V_(f)`

or,
`V_(i)` =
`(C_(f) * V_(f))/(C_(i))`

Putting the given values into the above formula we get the following.

`V_(i)` =
`(C_(f) * V_(f))/(C_(i))`

=
`(0.1 mg/ml * 0.1 ml)/(0.15 mg/ml)`

= 0.0667 ml

=
`6.67 * 10^(-2) ml * (1 microliter)/(10^(-3) ml)`

= 66.7 microliter

This means that volume of protein stock which is required is 66.7 ml. Hence, calculate the volume of water required as follows.

Volume of water required = Total volume - volume of protein stock

= (100 - 66.7) microliter

= 33.3 microliter

Thus, we can conclude that we need 33.3 microliter of water and 66.7 microliter of protein.