A fluorescent label for the specific and reversible labelling of the outer components of the plasma membrane. The reagent reacts with a fixed number of sites on the surface of cells concerned with anion permeation; does not pass through the osmotic barrier of the membrane; reacts under physiological conditions of temperature, pH and tonicity; and is detectable in small amounts. SEE ALSO NOTES FOR DIDS (CAT#D460600).Fluorescence: max. Abs. l = 336nm, max. Em. l = 436 nm.