The probe provided in Cat# 16316 is cell-impermeable and should be used to measure peroxynitrite anion (ONOO-) in solution.
The probes available in Cat# 16315 and Cat# 16317 are cell-permeable and can be used for intracellular ONOO- measurements. Cat#16315 is optimized for fluorescence microscopy and fluorescence microplate readers, and Cat# 16317 is optimized for flow cytometry.
All three assay kits are measured at an Ex/Em = 480/525 nm (green fluorescence).