How to Make 4% Paraformaldehyde (4%PF)
Make 4% PF 1000ml:
- Fill a 2000ml Beaker with about 400ml H2O, put a thermometer into the beaker. Heat beaker at hot stir plate to reach temperature at 62-64°C.
- 980ml RNAse free PBS in 1000ml bottle. Put a stir bar into PBS bottle. Add 100ul 10N NaOH (7 drops 10N NaOH) and 40g paraformaldehyde into PBS.
- Put bottle into beaker and stir the paraformaldehyde.
- Watch the temperature while stiring the paraformaldehyde. When the temperature reach to 62-64°C, the fixative will be clear gradually.
- Remove fixative from hot plate, cool down to room temperature.
- Filte fixative.
The pH of this fixative should be around 7.3; check pH is not necessary.
- Aliquot fixative and store at -20 °C.