Ok this is a bit of a stoichiometry question. There are four chemicals that need

Question

Ok this is a bit of a stoichiometry question.

There are four chemicals that need to be added to a serum that needs to total 150 microliters including the serum that is already there. Chemical A has an initial concentration of 0.1 mg/mL, chemical B has an initial concentration of 500 micrograms per milliliter, chemical C has an initial concentration of 0.125 mg/mL and chemical D has a concentration of 100 micrograms per 200 microliters.

How much of chemical A ,B,C and D need to be added to make the solution total 150 microliters total including the original solution?

Chemical A needs to have a final concentration of 2.5 micrograms per milliliter, chemical B needs a 1:200 dilution, chemical C needs a final concentration of 1.0 micrograms per milliliter and chemical D needs a 1:200 dilution as well.

Please show all work.

Explanation / Answer

Ans. Given:

# Initial solution:

[A] = 0.1 mg/ mL = 100 ug/mL                  ; [B] = 500 ug/mL                

[C] = 0.125 mg/mL = 125 ug/mL

[D] = 100 ug/200 uL

# Total volume of final serum solution to be made = 150.0 uL = 0.150 mL

# Requirement for final solution-

[A] = 2.5 ug/ mL                   ; [B] = 1:200 dilution             ; [C] = 1.0 ug/mL      

[D] = [B] = 1:200 dilution   

# Preparation:

# Required amount of stock A soln.:

Using C1V1 (initial stock soln.) = C2V2 (final soln.)

Now,

            Required volume of stock [A], V1 = (2.5 ug mL-1 x 0.150 mL) / 100 ug mL-1

            Or, V1 = 0.00375 mL = 3.75 uL

# Required amount of stock B soln.: A 1:200 dilution means there is 1 part of the original solution per 200 parts of the final/total solution.

So,

            Required volume of stock B soln. = (1 / 200) x Total volume to be made

                                                                        = (1 / 200) x 150.0 uL

                                                                        = 0.75 uL

# Required amount of stock C soln.:

Using C1V1 (initial stock soln.) = C2V2 (final soln.)

Now,

            Required volume of stock [A], V1 = (1.0 ug mL-1 x 0.150 mL) / 125 ug mL-1

            Or, V1 = 0.0012 mL = 1.20 uL

# Required amount of stock D soln. = 0.75 uL           ; [See #B]

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