Paraformaldehyde (PFA; 4% in PBS)
Add 4% (w/v) paraformaldehyde (PFA) to ±75% of the desired volume of Phosphate-buffered saline (PBS; 1×) in a glass beaker. Make sure to always wear a dust mask. To dissolve the powder, gently stir (using a stir bar and plate) and heat (until ±60°C) the PFA inside a fume hood. Cool down to room temperature and adjust the volume to 100% of the total volume with 1× PBS in a volumetric flask. Store the PFA for up to 1 wk at 4°C. Always use the PFA at room temperature.
