2% Formaldehyde Solution

Method 1: Formaldehyde preservative 

2% formaldehyde solution in protein-free PBS. 

Prepare as follows: 

• 10% formaldehyde* at 20 ml
• 10 x PBS at 10 ml
• Distilled water 70 ml * 

*10% formaldehyde solution (e.g., Polysciences, Warrington, PA, ultrapure, Cat.#04018), depolymerized paraformaldehyde, EM grade, methanol-free solution. 

Method 2: Formaldehyde Preservative 

2% formaldehyde solution in protein-free phosphate-buffered saline (PBS). 

Prepare as follows: 

Add 2 g paraformaldehyde powder (e.g., Sigma, St. Louis, MO) to 100 ml of 1 X PBS. Heat to 70°C (do not exceed this temperature) in a fume hood until the paraformaldehyde goes into solution (note that this happens quickly as soon as the suspension reaches 70°C). Allow the solution to cool to room temperature. Adjust to pH 7.4 using 0.1 M NaOH or 0.1 M HCl, if needed. Filter and store at 4°C protected from light.