# Blank - Why do you have to subtract the blank OD from the rest of the ODs? (Jul/22/2010 )

Why do you have to subtract the blank OD from the rest of the ODs before making your standard curve? Why can't you just calculate your curve from the optical densities given with the blank as a zero without subtracting the OD?

its basically the same you are suggesting. if blank = 0 you already subtracted the blank from all the others. just two ways of doing the same thing

-gebirgsziege-

Gradstudent78 on Jul 23 2010, 06:35 AM said:

Why do you have to subtract the blank OD from the rest of the ODs before making your standard curve? Why can't you just calculate your curve from the optical densities given with the blank as a zero without subtracting the OD?

it is not necessary to subtract the blank from all readings... u will still get the same results.... the slope remains the same!!!just that the blank subtraction gives the od or rfu values which are only of the analyte and not contributed by the blank and u know of the LOD and LOQ!!!
i dunno for elisa s (4PL graphs) but it shud hold true for all assays

-Prep!-