Preservatives for High pH (around 11)

Finding preservatives effective at a very high pH like 11 is challenging, as most common cosmetic preservatives work best in acidic to neutral ranges (typically pH 3-8 or 9).

Based on the available information, there are no broad-spectrum preservatives listed that are effective as the primary preservative at a pH of 11.

However, ingredients like Tetrasodium EDTA can be used in formulas with a pH between 8 and 12. Tetrasodium EDTA is not a preservative itself but acts as a chelating agent (cationizer). It helps to bind metal ions in water, which can improve the stability of the formulation and enhance the effectiveness of other ingredients, including some preservatives if they were able to function at that pH.

For formulations at pH 11, you might need to consider specialized preservation systems or adjust the pH to a range where common preservatives are effective. Always perform challenge testing to ensure the stability and safety of your product.