There are several advantages to using Dead Cell Apoptosis kits with Annexin V for flow cytometry in order to assay cell viability:

Superior brightness
Unlike other Annexin V kits that have lower protein concentrations or purification levels, the Annexin V Alexa Fluor 488 conjugate is optimized for flow cytometry to provide the largest separation between apoptotic and live cells. The Alexa Fluor 488 dye is a superior green-fluorescent dye with a spectrum similar to fluorescein (FITC).

High binding efficiency
Annexin V conjugates are made from a highly purified cys-annexin, resulting in higher binding efficiency and extremely accurate characterization of the apoptotic process.

Multi-parametric
Many publications require a minimum of two different ways to identify apoptotic cells. This multi-parametric kit detects phosphatidyl serine (PS) on the cytoplasmic surface of the cell membrane, while membrane integrity is determined via propidium iodide.

Dead Cell Apoptosis Kit with Annexin V Alexa Fluor 488 & PI
The Dead Cell Apoptosis Kit with Annexin V Alexa Fluor 488 & Propidium Iodide (PI) (V13241, V13245) is used in flow cytometry to measure early apoptosis by detecting phosphatidyl serine (PS) expression and membrane permeability. When cells are stained with Annexin V and propidium iodide, apoptotic cells expressing PS show green fluorescence, which can be detected in the FITC channel, and low red fluorescence. Dead or necrotic cells show bright red fluorescence and no green fluorescence, while live cells show no green or red fluorescence.

Dead Cell Apoptosis Kit with Annexin V PE and SYTOX Green
The Dead Cell Apoptosis Kit with Annexin V PE and SYTOX Green detects PS externalization in apoptotic cells during flow cytometry using recombinant annexin V conjugated to the orange fluorescent phycobiliprotein R-PE, while dead cells are detected with SYTOX Green nucleic acid stain. After treatment with both probes, apoptotic cells show orange fluorescence, dead cells show green fluorescence, and live cells show little or no fluorescence. These populations can easily be distinguished in the 530/30 nm and 585/42 nm bandpass filters with a 488 nm laser flow cytometer.

Dead Cell Apoptosis Kit with Annexin V APC and SYTOX Green
The Dead Cell Apoptosis Kit with Annexin V APC and SYTOX Green detects PS externalization in apoptotic cells during flow cytometry using recombinant annexin V conjugated to red laser-excited allophycocyanin, and dead cells using SYTOX Green nucleic acid stain. Apoptotic cells are detected by annexin V binding to externalized PS. Live cells show little or no fluorescence, apoptotic cells show red fluorescence and very little green fluorescence, and late apoptotic cells show a higher level of red and orange fluorescence. These populations can easily be distinguished using a flow cytometer that has both 488 nm and 633 nm excitation sources (an argon-ion laser and a HeNe laser).

The Dead Cell Apoptosis Kit with Annexin V FITC and PI
The Dead Cell Apoptosis Kit with Annexin V FITC and PI detects PS externalization in apoptotic cells using recombinant annexin V conjugated to green-fluorescent FITC dye and dead cells using PI. Necrotic cells that stain with PI show red fluorescence. After treatment with both probes, apoptotic cells show green fluorescence, dead cells show red and green fluorescence, and live cells show little or no fluorescence.