Which pair of reagents is used in Mayer hematoxylin preparation?

• A. Sodium iodate and ammonium aluminum sulfate
• B. Sodium iodate and ferric chloride
• C. Ammonium aluminum sulfate and ferric chloride
• D. Sodium iodate and sodium chloride

Answer: (A)

Mayer hematoxylin relies on two roles: activating the dye and forming a stable dye complex that binds nuclei. Sodium iodate acts as a mild oxidizer to convert hematoxylin into hematein, the activated form that can interact with a mordant. Ammonium aluminum sulfate provides aluminum ions that serve as the mordant, allowing the activated hematoxylin to form a stable hematein-aluminum complex that adheres to nuclear chromatin. This combination yields a crisp, long-lasting nuclear stain. Ferric chloride would change the oxidation environment and affect staining, while sodium chloride is just a salt and doesn’t participate in oxidation or mordanting. Therefore, the pair used is sodium iodate and ammonium aluminum sulfate.