Chelating
Citric acid can act as a mild chelating agent; citrate, usually in the form of trisodium citrate, may be given as an anticoagulant, because it chelates calcium ions, and therefore inhibits coagulation. Another application is in the form of iron(II) citrate as a nutritional supplement. Here, the benefit is the solubility as a chelate of the otherwise mostly insoluble iron.
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