Complexing agents

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Complexing agents are Lewis bases , i. H. chemical compounds or simple anions with lone pairs of electrons that form coordination compounds with metal ions or metal atoms as Lewis acids . They lead, for example, to a masking of (undesired) chemical properties of metal ions.

Areas of application

In food processing, certain complexing agents are added as food additives or are already natural components. The masking of metal ions ensures the stability of the color, aroma and texture of the food. They increase the effectiveness of antioxidants because free heavy metal ions catalyze oxidation . They are used in particular in canned vegetables, spice extracts and dairy products (because of their disaggregating effect on casein ). The sugar crystallization is also facilitated in the presence of complexing agents, since these destroy undesired sugar-metal complexes.

Various complexing agents serve as builders in detergents and cleaning agents to mask the hardness of the water . They are also used in the electroplating and printed circuit board industries .

In analytical chemistry , some complexing agents such as EDTA and nitrilotriacetic acid are used in chelatometry .

In medicine, among other things, the anticoagulant effect is important. Suitable complexing agents are added as anticoagulants to blood reserves and tubes for taking blood . In addition, certain complexing agents, such as dimercaptopropane sulfonic acid, are used to treat poisoning with heavy metals.

Examples

Iminodisuccinate tetrasodium salt is a readily biodegradable complexing agent that is used in water cycles to prevent and dissolve limescale deposits.

Fluoride masks iron (III) ions, which as a result no longer enter into the typical detection reaction with rhodanide .

1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is used as a complexing agent in nuclear medicine (for example in edotreotide ) and in magnetic resonance imaging (as gadoter acid ).

Triethanolamine is used as a basic component in soaps and cosmetics.

Food ingredients

Natural ingredients in food are z. B. dicarboxylic acids such as oxalic acid and succinic acid or, for example, hydroxy acids ( lactic acid , malic acid , tartaric acid , citric acid ). Also polyphosphates ( ATP and pyrophosphate ), amino acids , peptides , proteins and porphyrins are natural food ingredients that act complex forming.

Food additives

Individual evidence

  1. ↑ a b Hans-Dieter Belitz , Werner Grosch , Peter Schieberle : Textbook of food chemistry . 6th completely revised edition. Springer, Berlin / Heidelberg 2008, ISBN 978-3-540-73201-3 , p. 468 , doi : 10.1007 / 978-3-540-73202-0 .
  2. ↑ G. Jander, KF year, G. Schulze: measure analysis. 16th edition, de Gruyter, Berlin 2003, ISBN 3-11-017098-1 .