Preparation Paraformaldehyde PAF 4%
To prepare the PFA: watch out it is not easy, you have to use the chemical hood because and heat the solution otherwise it will not dissolve and you will kill yourself by inhaling this stuff!!!…
Morevoer, it takes a little while so prepare a lot and aliquot in 5ml so you’ll have enough for all year long. I keep my aloquots at -20oC and never use them more than twice, and never keep them at 4oC.
Place 450 ml of dH2O in a glass beaker. Heat to 60oC using a hot plate with stirring.
While stirring, add 20g of paraformaldehyde powder [Fisher #04042] to the heated water. Cover and maintain at 60oC.
Add 5 drops of 2N NaOH (1 drop per 100 ml). The solution should clear within a couple of minutes. pH 10 dissolves the paraformaldehyde. There will be some fine particles that will not go away. Do not heat solution too much above 60°C. PFA will dissociates and break down at temperature above 60oC.
Remove from heat and add 50 ml of 10X PBS. Adjust pH to 7.2; you may have to add some HCl. Final volume will be 500 ml. Place on ice, cover with foil to protect from the light. Sterilize through a 0.22 micron filter.
Use immediately, or aliquot may be frozen at -20oC and thawed as needed.
Preparation Paraformaldehyde PAF 4% —> PDF