Fluorometric determination of DNA in mammalian cell cultures by PicoGreen

An intercalating fluorochrome, PicoGreen, was assessed for its ability to d etermine the concentration of DNA in clarified mammalian cell culture broth s containing monoclonal antibodies. Fluorescent signal suppression was amel iorated by sample dilution or by performing the assay above the pI of secre ted IgG. The source of fluorescence in clarified culture broth was validate d by incubation with RNase A and DNase I. At least 91.8% of fluorescence wa s attributable to nucleic acid and pre-digestion with RNase A was shown to be a requirement for successful quantification of DNA in such samples.