Sep 01, 2025
Paraformaldehyde (4%)
- isabel.dilandro 1
- 1Claremont McKenna College
- Isabel DiLandro
Protocol Citation: isabel.dilandro 2025. Paraformaldehyde (4%). protocols.io https://dx.doi.org/10.17504/protocols.io.ewov11do2vr2/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: August 29, 2025
Last Modified: September 01, 2025
Protocol Integer ID: 225921
Keywords: paraformaldehyde
Abstract
4% PFA
Materials
Scale
Weigh boat
1L beaker
PBS
Paraformaldehyde powder
Sodium Hydroxide (NaOH)
Coffee filters
Funnel
Hot plate
Stir bar
Thermometer
1L bottle
Troubleshooting
Safety warnings
Do not inhale PFA powder, all mixing and weighing should take place under the fume hood
Directions
Add 800mL of PBS to your 1L beaker and place beaker on hot plate under the fume hood. Add a stir bar and heat while stirring up to 60°C.
Weigh out 40g of paraformaldehyde powder and add it to the beaker. The mixture will be very cloudy and will not clear right away.
Gradually raise the pH of the solution by adding drops of NaOH from a pipette until the solution clears. Once the solution is clear and paraformaldehyde has been dissolved, leave the solution to cool.
Once cooled, filter the solution through the coffee filter into your 1L bottle using a funnel.
Adjust the volume of the bottle up to 1L by adding PBS.
Store and refrigerate up to one month.