Is PEO/PEG incompatible with parabens?Does PEO/PEG deactivate parabens or tend to pull it out of solution? Preservatives for Cosmetics, 2nd. ed (Steinberg) notes thatParabens are inactivated (partially or fully) by strong hydrogen bonders, such as highly ethoxylated compounds like polysorbates, and compounds like cellulose derivatives, proteins and lecithin.If it’s the ethoxylated portion of a polysorbate that is interfering with the parabens, it stands to reason that PEG may deactivate parabens as well, since they are the same structure. And of similar concern would be any significant amount of PEGylated molecules. This comment here notes that:a word of warning: if you’re using ethoxylated emulsifiers (steareth-21,
oleth-5 etc.) there is a real chance that one or both of your parabens
will crash out of solution and crystalliseContext: Starting with a base preservative broth of:
This formula is crystal clear until I introduce PEG-90M at 0.5% or 1.0% (fairly high, this is for a lubricant). The sample becomes slightly hazy.I’m thinking I will try further dropping the propylparaben from the solubility limit at 25C (maybe to 0.32%) , but I am wondering if these ingredients are known to be generally incompatible from a preservative system standpoint.
- 0.20% Calcium Disodium EDTA
- 0.20% Methylparaben
- 0.04% Propylparaben
- 0.50% Phenoxyethanol