Vitamin C Serum Formulation and Stability

Based on the staff's feedback, here are the comments on your two proposed Vitamin C serum formulations:

Formulation 1:

• This formulation includes "Stabilized Vitamin C (Natural-C Glycol™) Serum" (ID 486), which the staff indicates is already a serum base.
• Adding other ingredients (Vitamin C (L-ascorbic acid), Phospholipid, Triethanolamine, Vitamin E, Ferulic Acid) to this base is generally unnecessary as the base is designed to be used as is.
• TaraGel™ (ID 2232) can be added if you wish to create a gel texture for the serum.

Formulation 2:

• This formulation includes Vitamin C (L-ascorbic acid) (ID 134). The staff correctly points out that L-ascorbic acid is highly unstable in water-based formulas and will degrade quickly, making the serum ineffective.
• While other ingredients in this formula (Perfect-C™ (Ascorbyl Tetraisopalmitate), Phospholipid, Ferulic Acid, Vitamin E, Vitamin C Ester (Ascorbyl Palmitate), Panthenol, Disodium EDTA, Active Resveratrol™, Light Cream Maker™, Xanthan Gum, Phenoxyethanol, Sodium Hydroxide, Triethanolamine) are generally compatible, the instability of L-ascorbic acid in a water environment is a major issue for creating an effective and stable Vitamin C serum.
• The formula also includes two other forms of Vitamin C (Ascorbyl Tetraisopalmitate and Ascorbyl Palmitate) which are more stable derivatives. It also includes two pH adjusters (Sodium Hydroxide and Triethanolamine).

Recommendations:

• For Formulation 1: Use the Stabilized Vitamin C (Natural-C Glycol™) Serum (ID 486) as your base. You can add TaraGel™ (ID 2232) for gelling if desired. Avoid adding the other listed active ingredients (2-6) as they are redundant or may affect the stability of the pre-made base.
• For Formulation 2: To create a stable Vitamin C serum, you should remove Vitamin C (L-ascorbic acid) (ID 134) from this water-based formula. You can utilize the more stable Vitamin C derivatives already included, such as Perfect-C™ (Ascorbyl Tetraisopalmitate) (ID 499) and Vitamin C Ester (Ascorbyl Palmitate) (ID 200). If you specifically want to use L-ascorbic acid, it requires a different formulation approach, typically anhydrous (without water) or at a very low pH (below 3.5), which might not be suitable for all skin types and can be challenging to formulate stably. The other ingredients in Formulation 2 are generally suitable for a serum.