|From:||"Smith, Allen" |
Neither "4% paraformaldehyde" nor "4% formaldehyde" accurately describes the solution, which is actually 4% methanediol (i.e., formaldehyde hydrate).
"4% paraformaldehyde" is a legitimate description of how the solution was made. It suggests that the solution was fresh and that very little formic acid or methanol had had time to form.
"10% formalin" is generally understood to mean: "I added 10 ml of what my supplier called 40% formaldehyde to 90 ml of water. I have no idea how pure the stock solution was."
Unfortunately "4% formaldehyde" is ambiguous because it does not tell how the solution was made.
Allen A. Smith, Ph.D.
School of Graduate Medical Sciences
Podiatric Medicine and Surgery
Miami Shores, Florida 33161-6695