Which definition best matches a chelating agent?

• A. A chemical that acts as a solvent for oils.
• B. A chemical that neutralizes acids.
• C. A chemical that reacts with metal ions to form stable water-soluble complexes.
• D. A chemical that polymerizes proteins.

Answer: (C)

A chelating agent is defined by its ability to bind metal ions through multiple donor sites, creating a stable, ring-like complex that stays soluble in water. This sequestration of metal ions is what makes the agent effective at removing metals from tissues or solutions, such as calcium in bone during decalcification, where EDTA forms strong complexes with Ca2+ to soften the tissue while preserving proteins.

So, the best answer describes a chemical that reacts with metal ions to form stable water-soluble complexes. The other descriptions don’t fit this role: a solvent for oils dissolves nonpolar substances, a neutralizer addresses acidity with bases or buffers, and a polymerizer would cause proteins to link together rather than bind metal ions.