When I image wet chromatography paper in a gel-doc, the intensity is not much. When I add a drop of ethidium bromide in water (0.5 ug/ml) on this paper, it gives a high intensity. Washing the paper with water does not really decrease the intensity.The same ethidium bromide solution, when imaged in a PCR tube, gives little intensity. It is clear that what I am seeing is not just paper's autofluorescence. It looks like EtBr binds strongly to cellulose. (1) Does anyone know if this is the case and why? (2) Is there a way to quench the fluroscence of EtBr on paper? Any help will be much appreciated. Thanks a lot.