Vitamin C Stability and Ingredient Compatibility in Formula

Question

I want to create a formula containing the following ingredients:

Vitamin C (L-ascorbic acid)
Cyclomethicone / Cyclopentasiloxane
Encapsulated Retinol (65K.IU/g)
Galactomyces Ferment Filtrate (Pitera) at 45%

Can these ingredients be mixed together? Specifically, will Cyclomethicone and Encapsulated Retinol affect the pH and stability of Vitamin C in the formula? I am concerned about the stability of Vitamin C.

MySkinRecipes Expert · Accepted Answer

Subject: Analysis of Vitamin C Formula

Based on the formula provided and the staff's analysis:

The main issue with this formula is the stability of Vitamin C (L-ascorbic acid).
Other ingredients can be mixed into the formula.
Cyclomethicone / Cyclopentasiloxane does not affect the pH of the formula.
Encapsulated Retinol (65K.IU/g) has a pH of around 4-6. While it might slightly increase the formula's pH, the amount used is small and does not significantly impact the stability of Vitamin C.
Other ingredients, particularly Galactomyces Ferment Filtrate (Pitera) at 45%, will have a greater impact on the formula's pH.
To improve the stability of Vitamin C, the formula's pH should ideally not exceed 3.5.

Recommendation:
After mixing the formula, it is recommended to measure the pH to ensure it is within the stable range for Vitamin C (pH <= 3.5).