Beyond EDTA: Chelation-driven stability & product protection in personal care
Dr Sabrina Behnke, director of marketing and growth, and Dr Elias Pambou, research & application development team leader, at Arxada, introduce Geogard NEU
Figure 1- How trace metals drive instability & where chelation intervenes
Trace levels of unbound iron and copper do not show up on a cosmetic ingredient label, but they exert a disproportionate influence on finished-product stability. In aqueous systems, these unbound metals can catalyse oxidation pathways that contribute to colour drift, fragrance degradation, off-odour formation and loss of performance long before a failure becomes obvious to the end user.
For this reason, chelation has long been a standard part of formulation design, particularly in surfactantbased systems and emulsions where raw materials, process water, packaging contact and manufacturing equipment can all introduce metal ions into the finished product.
Trace Fe 3 + and Cu 2
+ can enter formulations through process water, raw materials, packaging contact or manufacturing equipment. Left unmanaged, they can catalyse oxidation pathways that lead to discoloration, fragrance drift, active degradation and wider stability loss. Chelation helps interrupt this pathway by binding reactive metal ions before they initiate or accelerate downstream oxidation( Figure 1).
Metal ion
Fe 3
+ Iron
Cu2 + Copper
EDTA log K
Ethylenediaminetetraacetic acid( EDTA) has historically been the default solution because it offers broad utility, predictable processing behaviour and well-established performance. However, its role is now being reconsidered in some formulations, due to perceived environmental persistence, pressure to simplify ingredient
Etidronate log K
25.1 21.6 37.2
18.8 6.4 36.6
Table 1- Stability constants & practical chelation comparison
Gluconate log K
lists, and the broader shift toward multifunctional systems.
For chemists working on modern rinse-off and leave-on systems, the question is no longer whether metal control matters, but whether it can be delivered through chemistries that also support oxidative stability, preservation efficiency, and formulation economy.
56 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981