The demonstration of sulfated mucosubstances is possible with this stain

• A. Alcian blue 1.0
• B. Alcian blue 2.5
• C. Alcian blue 8GX
• D. Alcian blue pyridine variant

Answer: (A)

Sulfated mucosubstances are best demonstrated when the staining depends on which groups remain negatively charged at a given pH. Alcian blue is a cationic dye that binds to negatively charged mucosubstances. At a very acidic pH (around 1.0), the carboxyl groups of many mucosubstances are not deprotonated and thus not negatively charged, while the sulfate groups remain strongly negatively charged. This makes the dye bind specifically to sulfated mucosubstances, allowing their demonstration.

If you use a higher pH, such as 2.5, both sulfated and carboxylated mucosubstances carry negative charges and bind the dye, so the staining isn’t specific for sulfated mucosubstances. Alcian blue variants exist for different pH ranges, but for showing sulfated mucosubstances specifically, the low-pH approach is the key.