The Viability Dye 506 can be used to exclude non-viable cells in flow cytometry assays. It irreversibly binds to cell surface and intracellular amines. The dye can covalently bind to a higher concentration of amines in cells that have lost plasma membrane integrity, such as those in the late stages of apoptosis or dead cells, and generate a significantly more intense fluorescence signal. The advantage of this viability dye over propidium iodide and 7-AAD, is that the cells it denotes can be washed, fixed, permeabilized and intracellularly stained without losing the fluorescence of the viability staining.  The Viability Dye 506 can be excited by the violet (405nm) laser and has a peak emission of 506nm detectable by the 510/50 band pass filter.