What exactly is an OD?
RESPONSE:Optical density (OD)=log10( Ii / It) where Ii = Intensity of incident light, It = Intensity of transmitted light. An OD unit (ODU) is the absorbance on a 1mL solution, typically in water, measured at 260nm in a 1cm path-length cuvette. One ODU represents ~33ugrams of single-stranded oligonucleotide and 1umole of oligonuclotide will absorb ~10ODU/base.