chelating agents

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chelating agents (kē´lātĬng). Certain organic compounds are capable of forming coordinate bonds (see chemical bond) with metals through two or more atoms of the organic compound; such organic compounds are called chelating agents. The compound formed by a chelating agent and a metal is called a chelate. A chelating agent that has two coordinating atoms is called bidentate; one that has three, tridentate; and so on. EDTA, or ethylenediaminetetraacetate, (-O2CH2)2NCH2CH2N(CH2CO2-)2, is a common hexadentate chelating agent. Chlorophyll is a chelate that consists of a magnesium ion joined with a complex chelating agent; heme, part of the hemoglobin in blood, is an iron chelate. Chelating agents are important in textile dyeing, water softening, and enzyme deactivation and as bacteriocides.

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chelating agents Chemicals that combine with metal ions and remove them from their sphere of action, also called sequestrants. They are used in food manufacture to remove traces of metal ions which might otherwise cause foods to deteriorate and clinically to reduce absorption of a mineral, or to increase its excretion; e.g. citrates, tartrates, phosphates, and EDTA.

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chelating agent (kee-layt-ing) n. a chemical compound that forms complexes by binding metal ions. Some chelating agents, including desferrioxamine and penicillamine, are drugs used to treat metal poisoning: the metal is bound to the drug and excreted safely.