The routine Alcian blue stain is done at a pH of 1.5.

• A. True
• B. False
• C. It is done at pH 7.0
• D. It depends on tissue

Answer: (B)

Alcian blue staining relies on acidic mucins carrying negative charges to bind the dye, so the pH is set to a defined acidic value. The standard routine uses pH 2.5, which allows both sulfated and carboxylated mucins to stain blue. Dropping the pH to 1.5 would protonate some carboxyl groups, reducing binding for those mucins and highlighting mainly sulfated mucins—not the typical broad staining seen at 2.5. A neutral pH like 7.0 wouldn’t promote proper binding either. While some specialized procedures differentiate mucin types by pH, the routine Alcian blue stain is not performed at 1.5. Therefore, the statement is false.