Propidium Iodide Spectrum

Molecular Structure of Propidium Iodide. Diagram depicts the skeletal structure of propidium iodide, chemical formula C₂₇H₃₄I₂N₄.

Propidium Iodide (PI) binds nucleic acids by intercalation in the bases. When bound to nucleic acid it has an excitation maxima ~535 nm and an emission maxima ~615 nm. On a flow cytometer PI is typically excited by 488 or 561 nm and can be detected in a 610/20 bandpass.

Propidium Iodide Spectrum. Analysis of excitation, dotted line, and emission, solid line, of propidium iodide in aqueous solution.