What formaldehyde solution should I use for cross-linking cells/tissue in my Chromatin Immunoprecipitation (ChIP) experiment?

At CST, we use methanol-containing formaldehyde, specifically product F8775 from Sigma, to increase the shelf-life of our reagents. Therefore, it is not necessary to use methanol-free formaldehyde to cross-link your samples.

Regardless of the type of formaldehyde used, it is necessary to ensure that the final concentration of formaldehyde is 1% in the plate or tube.

Important note: Paraformaldehyde (PFA) is not a cross-linker and will result in a failed Chromatin Immunoprecipitation (ChIP) experiment.

Last updated: June 30, 2026