Question

The molecular weight of vincristine, a pharmaceutical drug, is 923.04 g/mol. It is supplied in 1 mg per vial. You want to treat your culture cells with a final concentration of 7 hM vincristine and will need 12 mL of cells for your experiment. You only want to add 21 mL of vincristine solution to your cells. What concentration should you make your stock solution of vincristine in order to make this 21 uL addition?The molecular weight of vincristine, a pharmaceutical drug, is 923.04 g/mol. It is supplied in 1 mg per vial. You want to treat your culture cells with a final concentration of 7 hM vincristine and will need 12 mL of cells for your experiment. You only want to add 21 mL of vincristine solution to your cells. What concentration should you make your stock solution of vincristine in order to make this 21 uL addition?

Answer 1

First we shall convert all units to the same prefix, giving molarity in mM and volume in mL:

1 ul = 0.001 mL

5 nM = 5 x 10?? mM

We can calculate the concentration of stock solution using the following equation:

MiVi = MfVf

Where:

Mi - Initial molarity
Vi - Initial volume
Mf - Final molarity
Vf - Final Volume

Substituting the values we get:

Mi x 20 mL = 5 x 10?? mM x 0.001 mL

Rearranging to give an equation for Mi we get:

Mi = (5 x 10?? mM x 0.001 mL) / 20 mL = 2.5 x 10?