1. Add 1 µl of 1 mg/ml 7-AAD (1 µg/ml final) to approximately 1x106 washed cells suspended in 1 ml PBS.
2. Incubate ≥30 min in the dark on ice.
3. Analyze on flow cytometer with excitation at 488 nm. Collect fluorescence emission with a 650-nm long-pass or a 670 ± 20–nm band-pass filter.
7-AAD is easily excited at 488 nm. The fluorescence emission of the dye has a peak at ∼670 nm.
From Current Protocols in Flow Cytometry