Chelation 2 : In chemistry, this describes the combination of a metallic ion with heterocyclic ring structures in such a way that the ion is held by bonds from each of the rings
Heriot-Watt University, School of Life Sciences, Some Terms Used In Toxicology and Chemical Safety, Edinburgh, UK 1992. http://www.who.int/ipcs/publications/methods/harmo nization/en/compilation_nov2001.pdf, (Tox and Chem Sfty - Amer) {85}