Compatibility of Zinc PCA, Sodium PCA, and EDTA

Regarding your question about using Zinc PCA or Sodium PCA with EDTA, based on the information that copper peptide should not be used with Disodium EDTA:

• Zinc PCA and Disodium EDTA: As confirmed by the staff reply, Zinc PCA and Disodium EDTA can be used together in a formulation. While Zinc PCA contains zinc, it is already in a stable complex form. Disodium EDTA acts as a chelating agent that primarily binds to free metal ions in the water or other ingredients, helping to stabilize the formula and prevent unwanted reactions caused by these free ions. The interaction between pre-complexed Zinc PCA and Disodium EDTA is generally not an issue in standard cosmetic formulations.

• Sodium PCA and EDTA: Sodium PCA is a humectant and a component of the skin's Natural Moisturizing Factor (NMF). It is not a metal complex in the same way as copper peptide or Zinc PCA. There is no known incompatibility issue with using Sodium PCA alongside EDTA in cosmetic formulations. EDTA will perform its function of chelating free metal ions without negatively impacting Sodium PCA.

In summary, you can generally use both Zinc PCA and Sodium PCA in formulations that contain Disodium EDTA or other forms of EDTA. The caution regarding copper peptide and EDTA is specific to the interaction between the copper peptide complex and the chelating agent, which does not apply in the same way to Zinc PCA or Sodium PCA.