Staurosporine (FW: 466.53 g/mol) is a potent reagent used to inhibit various PKC

Question

Staurosporine (FW: 466.53 g/mol) is a potent reagent used to inhibit various PKC isoforms in human cell lines, and is supplied in a vial containing 2 mg of lyophilized powder. You want to treat 12 ml of HL-60 cells with a final concentration of 5 nanoMolar staurosporine, and you only want to add 6 microLiters of staurosporine solution to the cells. What concentration should you male your stock solution of staurosporine in order to make this 6 microLiters addition? Based on this concentration, how would you make 100 mL of the staurosporine stock solution using DMSO as a solvent?

Explanation / Answer

You have to use the relationship

Molarity 1 * Volume 1 = Molarity 2 * Volume 2

Solution 1

Volume is 12 ml

Molarity is 5 nM

Solution 2

Volume is 6 microliters

Molarity = ?

The first thing we need to do is change 12 ml to microliters or changing 6 microliter to mililiters. I´m changing 12 ml

1 mililiter is 1000 microliters

12 ml are 12000 microliters.

We apply the equation

12000 microL.* 5 nM = 6microL * X nM

X = 10, 000 nanoMolar

or

Concentration = 10 micromolar

b) If we want to make a stock solution of 10 micromolar in 0.1 L

moles = 0.00001 molar * 0.1 L = 0.000001 moles

weight = 0.000001 * 466.53 = 0.00046653 grams

This is 0.46653 mg

You need to dissolve 0.46653 mg in 100 ml. Since it is a very small ammount you can take the 2 mg (pill or compound) that has 4.28697 x 10-6 moles and then just add solvent until you reach 10 micromolar. this is

Volume = moles / Molarity

= 4.28697 x 10-6 moles / 0.000 01 molar

= 0.42869 Liters or 428.69 mililiters

So I would take the 2 mg pill and ad 428.69 mililiters and then I would just take 100 ml of that solutions, also you could make more stock 100 ml solutions from this.

Other way to do this is adding 2 mg to 2 ml, this would give 1 mg / ml, then you could take 0.466 ml and put it on another flask then you can add (100 - 0.466 =) 99.533 ml or 100 ml

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