I have performed MTT assay with cell densities ranging from 1000-9000 cell and added MTT after 24h of incubation. The resulting absorbance is less than 0.75. Hence I selected higher cell densities ranging from 10000-30000 and the resulting absorbance for 30000 was 0.66.
Now my question is can I select this higher cell density to determine IC50 of drug?
OR ELSE
I should consider low cell density and incubate them for 48h or 72h to get the absorbance in range of 0.75-1.25?
Thank you