Author: Unknown Date: Unkown

Fixing Cells with Paraformaldehyde

Hazards: Carcinogenic at low doses. Fumes and contact are dangerous.
Protection: wear gloves when handling formaldehyde. Wear mask and goggles when preparing from powder. Mix in chemical waste hood.
Waste: Discard formaldehyde by emptying into hazardous waste container. Store in chemical waste hood until picked up by waste disposal.
Spill clean-up: refer to MSDS. Any spill over 25 µl is considered hazardous.
Storage: Store powder on chemical shelf. Store liquids in opaque containers at 4ºC. Use within five days. Label all containers as carcinogenic.
Procedure:
For up to 5x106 cells:
1. Paraformaldehyde preparation:
B) From 16% sealed vials. Break vial, dilute to desired concentration using 10x PBS and ddH2O to a final concentration of 1xPBS. (To make 12 ml of a 1% solution, add 750 µl 16% PFA to 1.2 ml 10xPBS to 10.05 ml ddH2O.
C) Make 4% solution from powder: Add 4 g of PFA to 96 ml PBS in 250 ml beaker. Place on hot plate set at approx 4.5 (don’t bring temp above 80ºC) with stirrer at 2.5. Mix for approx 30 min. Cool
D) Store in opaque container at 4ºC. Use within five days. Otherwise will decompose.
2. Start with a cell pellet
3. Resuspend pellet in 1 – 4 % PFA (either 200 µl in 96 well-plates, or 1 ml in eppe tubes).
4. Let sit 20 min at RT.
5. Pellet cells and wash with 1x PBS.