Important: Prepare solution under the ventilation hood, always wear gloves, mask, and goggles!

1 liter of 0.1M PB (pH 7.35)

40 grams of paraformaldehyde

1. 40 g paraformaldehyde (PF)
2. Place a 1 or 2 L Erlenmeyer flask on a stirring hotplate (in hood!), with a stir bar.
3. Pour the 40 g of PF into the flask + 500 mL of 0.1 PB, and begin stir (the other 500 mL will be added later).
4. On a holding bar (attached to the hotplate), place a thermometer and place into the solution to obtain continuous readings of temperature in the  solution.
5. Gradually start heating.
6. Wait for the temperature to rise, do not allow to rise above 60 degrees. If temperature reaches 60 degrees, and turning down the heat knob does not slow the increase, then use some of the remaining 500 ml 0.1 M PB solution to cool the solution.
7. After the temperature in the solution reaches ~60 degrees (and stays constant), the solution should begin to change from a cloudy to a clear solution.
8. After it clears, continue to stir at 60 degrees for an addition 5-10 min.
9. Now, you must filter the solution before use.
10. Filter.
11. pH the filtered solution to 7.35.
12. Store in +4 degrees, allow it to cool, before using it.