Formaldehyde (4%, w/v in PBS)
MATERIALS
Reagents
NaOH (2 M) (optional; see Step 2)
Paraformaldehyde (EM Grade, purified, prill form) (Electron Microscopy Sciences, Inc.)
Equipment
Filter unit (disposable, 0.22 μm)
Tube (50 mL)
Water bath or incubator preset to 60°C
METHOD
-
1. Dissolve 4 g of paraformaldehyde in 50 mL of H2O in a 50-mL tube.
-
2. Heat at 60°C until dissolved.
Add a few drops of 2 M NaOH to help dissolve, if necessary.
-
3. Cool to room temperature.
-
4. Add an equal volume of 2X PBS.
-
5. Filter with a 0.22-μm disposable filter unit.
