Isn't formalin just the 37% aqueous solution of formaldehyde? Formaldehyde is a gas, H2C=O. Paraformaldehyde is a solid, sparingly soluable in water. Paraformaldehyde is a polymeric form of formaldehyde, (H2C0)N. If you are stirring a powder into water ovenight (or a shorter time in warm aqueous NaOH) to make your fixative, you are making a solution of paraformaldehyde (probably 1 or 2% w/v). If your fixative comes out of a big plastic jug from Sigma (etc.), it is formalin. Mark Miller mamiller@wista.wistar.upenn.edu
This archive was generated by hypermail 2b29 : Wed Apr 03 2002 - 11:49:17 EST