Chelation

complex formation involving a metal ion and two or more polar groupings of a single molecule

Description
Chelation can be used to remove a metal ion from participation in biological reactions, as in the chelation of Ca2+ of blood by EDTA (which thus acts as an anticoagulant in vitro). In vivo, chelation normally refers to the process of iron chelation by desferrioxamine or deferiprone, or ICL670 in iron-overloaded patients, more rarely to the chelation of aluminium and other metals.