Which statement best describes the role of ammonium aluminum sulfate in hematoxylin staining?

• A. Stabilizes hematoxylin solutions
• B. Ripes hematoxylin
• C. Causes color change to blue
• D. Has no effect

Answer: (A)

The key idea is that aluminum salts act as a mordant in hematoxylin staining. Ammonium aluminum sulfate provides aluminum ions that form a complex with oxidized hematoxylin (hematein), which then binds to tissue and stays fixed during processing. This mordanting stabilizes the dye so the stain remains vivid and resists rinsing or fading. While whitening, aging, or oxidizing steps can influence hue and intensity, the primary role of ammonium aluminum sulfate is to stabilize and fix the hematoxylin complex rather than change color or have no effect.