Which statement is true regarding mercuric chloride in common fixatives discussed here?

• A. Both contain mercuric chloride
• B. Only Bouin contains mercuric chloride
• C. Only 10% NBF contains mercuric chloride
• D. Neither contains mercuric chloride

Answer: (D)

Mercuric chloride is found in some older mercurial fixatives, but it is not present in the common fixatives discussed here. Bouin’s solution is made of picric acid, formaldehyde, and acetic acid, with no mercury, and 10% neutral buffered formalin is simply formaldehyde in phosphate buffer, also without mercury. Therefore, in the fixatives considered, mercuric chloride is not included.

Note: other mercurial fixatives (not in the set discussed) do contain mercuric chloride, such as Zenker’s or Helly’s, but those aren’t part of the current context.