Calcein Violet 450 AM is a membrane-permeable live-cell labeling dye. Upon entering the cell, intracellular esterases cleave the acetoxymethyl (AM) ester group, yielding the membrane-impermeable Calcein Violet fluorescent dye. Apoptotic and dead cells with compromised cell membranes do not retain Calcein Violet 450. Calcein Violet 450 is optimally excited at 408 nm and has a peak emission of 450 nm. For fluorescent microscopy, Calcein Violet 450 can be detected using the appropriate filter sets. For flow cytometric analysis, it can be excited off of the violet laser line (405 nm) and detected using filters for Pacific Blue®/eFluor® 450 (450/50). Co-staining with Annexin V or 7-AAD is recommended to allow the greatest resolution between live and dead/apoptotic cells. Molecular weight: 600 Peak excitation: 408 nm Peak emission: 450 nm Calcein Violet 450 AM should be reconstituted in high-quality, freshly opened DMSO. Once reconstituted, it should be stored at -20°C with dessicant and used within a short period of time. Avoid freeze-thawing.