Hematoxylin solutions with which chemical are considered stable?

• A. Ferric chloride
• B. Ammonium aluminum sulfate
• C. Sodium sulfate
• D. Sodium chloride

Answer: (B)

Hematoxylin solutions stay stable when a metal mordant is present to form a dye complex that resists fading. The aluminum-based mordant, provided by ammonium aluminum sulfate, binds the oxidized form of hematoxylin (hematein) to create a colored, long-lasting complex. This combination gives the solution good shelf life and consistent staining because the aluminum ion stabilizes the dye and helps it adhere to tissue once bound.

Ferric chloride introduces iron, which can act as an oxidizer and can lead to less predictable staining and faster fading in some cases. Sodium sulfate and sodium chloride don’t supply a mordant to stabilize the hematoxylin complex, so they don’t improve stability. Hence, ammonium aluminum sulfate is the stabilizing choice.