Which statement is true about formic acid in relation to ion exchange resins?

• A. Formic acid is used with ion exchange resins.
• B. Formic acid is never used with ion exchange resins.
• C. Formic acid is used with ion exchange resins only after decalcification.
• D. Formic acid is used with ion exchange resins to dehydrate tissues.

Answer: (A)

Formic acid is used as a gentler decalcifying agent, and in some protocols it works together with ion-exchange resins. The resin helps remove calcium released during decalcification and helps maintain a stable, suitable pH as the acid penetrates the tissue. This combination lets decalcification proceed with less damage to cellular detail and preserves morphology better than stronger acids. It is part of the decalcification step itself, not a dehydration step, which is done later with graded alcohols. Therefore, using formic acid with ion-exchange resins is a recognized approach, making it the correct statement.