Chelating agent

Chelating agents (from Greek chel = crab claw), also called complexing agents, are chemical compounds that form complexes with metal ions. Among other things they are used as additives in cosmetic products.

The chelate complex - also called chelate in short - describes compounds where a multidentate ligand (which has more than one free electron pair) occupies at least two coordination sites (binding sites) of the central atom. The central atom is usually a double positively charged metal ion (such as Fe++, Cu++). Ligand and central atom are linked by coordinative bonds.

Chelating agents are used to bind or remove disturbing chemical properties of metal ions.

In cosmetic products chelating agents are used as additives.

In detergents chelating agents are used to bind calcium ions. This prevents lime deposits on appliances and laundry.

Chelating agents are used as additivesin food . Here chelate complexes ensure the stability of colours and flavours of the food. Furthermore chelating agents increase the effect of antioxidants.

In medicine, chelates are added to blood products as anticoagulants, for example.

Natural chelating agents are e.g. dicarboxylic acids such as oxalic acid and succinic acid; furthermore also various hydroxy acids such as lactic acid, malic acid, tartaric acid and citric acid. Further natural chelates are polyphosphates (ATP and pyrophosphate), amino acids, peptides, proteins and porphyrins.