please help with dilutions?

[magentacatz]

Please help?
I've been trying to understand this for hours but for some reason I just do not understand serial dilutions


I have a stock solution of 0.25 miligrams/mL and I have to get it to a concentration of 100 nanograms/mL and then also to 10 nanograms/mL.

I've done the whole C1V1 = C2V2 thing but it does not work for serial dilutions. I never learned about serial dilutions in college and now I have to do it in lab.

[MrMistery]

you set c1=0.25 miligrams/mL
c2=100 nanograms/mL
v2=whatever volume you need of your 100 nanograms/mL solution.

then you calculate your v1.

Once you have your 100 nanograms/mL you can do the following thing: use the same formula, setting c1=100 nanograms/mL, c2=10 nanograms/mL and v2=whatever volume you need of the 10 nanograms/mL solution, and then calculate v1 (in this particular case, you will only need to dilute your 100 nanograms/mL solution 10 times).

Cheers,
Andrei