Comments on the determination of nucleic acids in natural waters by the CTAB-DABA-orcinol method

Karl and Bailiff (1989) presented the CTAB-DABA-orcinol method for the determination of dissolved DNA (D-DNA) and RNA (D-RNA) in natural waters. Here we demonstrate that, by this method, no only RNA but also heteropolysaccharides containing pentose sugars are precipitated and measured. RNase treatment resulted in only a slight reduction of the measured D-RNA concentrations in seawater. These findings indicate that the CTAB-orcinol method is not specific for measuring D-RNA. We improved the accuracy of the CTAB-DABA assay for determining D-DNA in seawater and we further show that viral DNA is probably also measured by the CTAB-DABA method.