I need to dilute a 0.28 ug/uL solution to obtain a 100 ng/ul solution. How should I make the dilution?

Answer 1

0.28ug=280 ng
280/100=2.8
The solution should be diluted 2.8 times
Make the volume of the present solution 2.8 times ... u achieve required dilution.
That is if u have 1 ul of the undiluted solution add 1.8 ul of the solvent.

Answer 2

0.28 ug/ul = 280 ng/ul

280ng/(1ul+x ul)= 100 ng/ul
280 = 100 + 100 x
180 = 100x
x= 1.8

That is, you need to add 1.8 ul of water to 1 ul of your 0.28 ug/ul solution to get 2.8 ul of 100ng/ul solution

To get 100 mL of 100 ng/ul, do this:

100 mL/2.8 =35.7 mL

So add 35.7 mL of 0.28 ug/ul to 64.3 mL of water (100 minus 35.7) and you get 100 mL of 100 ng/ul