Purity ≥95% (HPLC). Propidium Iodide is a phenanthridine compound, a class of compounds with reported activity against several species of trypanosomes. Propidium iodide may be used in flow cytometry to evaluate cell viability when used with other dyes that stain viable cells or cells that are early in the apoptosis process. Propidium iodide (PI) is a fluorescent dye [FW 668.41] that binds specifically to DNA. This property has led to its common use in evaluation of cell cycle, aneuploidy and apoptosis by flow cytometry. When excited by a laser light at 488nm, PI emits a signal that can be monitored by the red wavelength detector typically reserved for phycoerythrin (usually FL2). Propidium iodide is excluded from viable cells, thus analysis of DNA content in cells requires membrane permeabilization. In evaluation of apoptosis, PI is used to distinguish necrotic cells or cells in late stages of apoptosis, which have permeabilized membranes and thus bind PI, from viable cells or cells in