Methaemoglobin

Ferri-hemiglobindie; ferric-III-containing oxidized form of hemoglobin (Hb) with coordinative binding of water (acid methemoglobin) or -OH (alkaline methemoglobin = hemiglobin hydroxide). Formed when Hb is exposed to oxidizing agents (e.g. nitrite, methylene blue, hydrogen peroxide) and is no longer capable of oxygen transport.