The Personal Care Product Council’s online ingredient dictionary, the wINCI, defines chelating agents or sequestrants1 as “ingredients that complex with and inactivate metallic ions to prevent their adverse effects on the stability or appearance of cosmetic products.”2 Metallic impurities can come from many different sources, primarily from either the ingredients themselves—specifically those that are naturally derived, the water system, or minute extractions from metallic equipment and storage containers. If not deactivated, these metallic ions can deteriorate cosmetic products by reducing clarity, compromising fragrance integrity and causing rancidity/oxidation.
The mechanism for chelation, described as a chelate complex, is based on multiple bonding (polydentate ligand) around a single central atom. Common chelating agents include ethylenediaminetetraacetic acid (EDTA) and its derivatives, etidronic acid and its derivatives, galactaric acid, sodium metasilicate and phosphate derivatives. Disodium EDTA and tetrasodium EDTA are two popular chelators used in the US personal care industry. Chelators are used in almost