# Dilution help - changing units (May/22/2006 )

Hello All:

Im sorry for this another topic regarding dilutions.. ive been through all the dilution topic in this fourm and non of them did actually help me...

anyway... lets suppose that i want to dilute 10uM to 1pmol in 100ul... i already knew the answer which is 10 uL, but want to be sure from where did it come and how.

i know we use the C1.V1=C2.V2

after changing the c1 unit to pmol , C1 = 10 000 000 pmol

applying the formula

V1= 1.100/10 000 000

V1= 0.00001

what is the final answer unit.. is uL, L or mL?

some said you have to differnt concentrations one is in M and the other is in mol..

thanks for looking...

nop

1 pmol/100 ul is equal to 0,01uM

so you have to make a dilution 1/1000 of your 10 uM stock to get 1 pmol/100ul (or 0,01uM)

if you want to use the formula, first define what volume you need

eg ... for a final V of 1 ml

CfVf=CoVo

Vo = 0,01uM * 1ml / 10 uM

you get 0,001 ml

or 1 ul

in others... a dilution 1/1000

1 M is 1 mol/L

Go to this site. It helps with calculations.

http://www.graphpad.com/quickcalcs/Molarityform.cfm

Oh well, links...

Lecture notes on concentration:

http://www.chembuddy.com/?left=concentration&right=toc

Concentration cheat sheet:

http://www.chembuddy.com/?left=CASC&right=...ion-cheat-sheet

Note that when calculating dilutions you may mix different units of concentration and volume as long as all voulmes are expressed in the same units (like L, mL, UL) and all concentrtations are expressed in the same units (M, mM, uM). If you want to use different units - like L and mL - at the same time, you must add conversion factor of 100 somewhere.