Morning Argha, propidium is being used as a viability dye and/or evaluate DNA fragmentation @ 1-2µg/ml(final dilution) in combination with AnnexinV. Similar concentrations can be used for DAPI and Hoechst to allow combinations of other AnnexinV conjugates. While 7-AAD is generally used a higher concentration(5µg/ml) and requires longer incubation.