Chelating Agent

A chelating agent is an ingredient that binds trace metal ions so they cannot take part in reactions inside a product. It is a stability ingredient: its work is done in the bottle, not on skin.

Metal ions arrive unavoidably, in water, in mineral raw materials and from manufacturing equipment. Even at parts-per-million levels they catalyse oxidation, which is how a serum browns, a fragrance turns and an easily oxidised active loses strength before the expiry date. A chelator wraps those ions in a claw-shaped structure — the name comes from the Greek for claw — and takes them out of circulation.

Chelators also make many preservative systems work harder than they otherwise would, because some microbes depend on trace metals too. That is why a formula can often use less preservative when a chelator is present.

• Disodium EDTA is the long-established option and the one most often seen on labels.
• Tetrasodium glutamate diacetate and sodium phytate are frequent substitutes chosen on biodegradability grounds.
• Their presence says something about formulation care and nothing about how well a product will work on skin.

A chelating agent has no active effect of its own, so it is not a reason to choose or avoid a product. It is worth recognising on a label mainly so it is not mistaken for an active ingredient.