Ready-to-use formaldehyde-based fixation buffer for immunofluorescence staining for microscopy or flow cytometry. Also available in the Flow Cytometry Fixation/Permeabilization Kit. Note: this fixative is prepared with methanol-stabilized formaldehyde. For methanol-free formaldehyde fixative, see our Paraformaldehyde, 4% in PBS, Ready-to-Use Fixative.