Originally Posted by mcdeena
For dilution, I add 10 microlit of the stock to 90 microlit of 10% DMSO in tubes. From there, I transfer 10 microlit from the tube + 190microlit cell suspension in the well. This will gives me 100mcg/mL concentration.
Didn't notice that underlined part the first time.
I don't think you need to dilute into 10% DMSO just use molecular grade water.
I think you are ending up with
%DMSO = (10 *100%/100) + (90*10/100) = 10% + 9% = 19%DMSO at 1st dilution
Makes sense because 90ul at 10% would be 9ul of DMSO + 10ul 100% DMSO = 19ul of DMSO / 100ul total volume
Like I said you don't need to dilute into 10% solution, unless you can also dissolve the curcumin into pure water, then your method would work and give you the 0.5% DMSO final conc'n.