Formulating Vitamin C Serum (Skinceuticals Type): Ingredients, Preservation, and pH Adjustment

Question

I'm interested in formulating a Vitamin C serum similar to Skinceuticals C E Ferulic. I have some questions regarding ingredients and formulation: I've heard about different forms of Vitamin C like Magnesium Ascorbyl Phosphate, Sodium Ascorbyl Phosphate, Ethyl Ascorbic Acid (3-O-Ethyl-L-ascorbic acid), and Ascorbyl Glucosamine. How effective are these forms, particularly for skin brightening/whitening, compared to L-Ascorbic Acid or Tetrahexyldecyl Ascorbate? In a formula based on L-Ascorbic Acid (like Skinceuticals C E Ferulic), can I add Lemon Peel Bioferment? If so, how would it affect the formula, especially the pH, and what adjustments would be needed? Is it necessary to include preservatives in this type of low pH formula (around 3.5-4), especially when ingredients like Hyaluronic Acid are present? What is the specific role of Triethanolamine in this formula? How does it help in adjusting the pH, and what is the target pH range considering the stability of L-Ascorbic Acid (15%) and the compatibility with other ingredients like Panthenol (Vitamin B5) and Hyaluronic Acid? Is Glutathione typically included in this type of formula?

MySkinRecipes Expert · Accepted Answer

Formulation Questions for Skinceuticals C E Ferulic

Here are the answers to your questions regarding the formulation of a Skinceuticals C E Ferulic type serum:

Adding Lemon Peel Bioferment

Yes, you can add Lemon Peel Bioferment to your formula. This ingredient acts as a tyrosinase inhibitor, helping with skin brightening, and also provides antioxidant benefits. However, since Lemon Peel Bioferment has a pH of around 5-6, adding it will increase the overall pH of your formula. To maintain the optimal pH range of 3.5-4 for the stability and effectiveness of L-Ascorbic Acid, you will need to reduce the amount of Triethanolamine used for pH adjustment accordingly.

Preservatives in Skinceuticals C E Ferulic

Yes, preservatives are necessary in this type of formula. Although the low pH required for L-Ascorbic Acid stability (3.5-4) provides some inhibitory effect on microbial growth, it is generally not sufficient to fully preserve the product, especially when other ingredients like Hyaluronic Acid are present, which can be degraded by bacteria if not properly preserved. Therefore, adding a suitable preservative is recommended to ensure product safety and shelf life.

Role of Triethanolamine and pH Adjustment

Triethanolamine is used in the formula to adjust the pH upwards. L-Ascorbic Acid, especially at a concentration of 15%, is highly acidic and will lower the pH of the solution significantly below the desired range of 3.5-4. This specific pH range is critical for the stability and optimal absorption of L-Ascorbic Acid. While other ingredients like Panthenol (Vitamin B5) and Hyaluronic Acid can tolerate a wider pH range (Panthenol 3.5-7.0, Hyaluronic Acid 3.0-9.0), the pH of the formula is primarily adjusted to ensure the efficacy and stability of the main active, L-Ascorbic Acid. A target pH of 3.5 is ideal for L-Ascorbic Acid, but adjusting to around 3.8, as found in the original Skinceuticals, can be a good compromise that is still effective for Vitamin C while being tolerated by other ingredients. Regarding your mention of Glutathione, it is not typically included in the standard Skinceuticals C E Ferulic formula.

In summary, Triethanolamine is essential to bring the pH of the highly acidic L-Ascorbic Acid solution up to the narrow range required for its stability and effectiveness, balancing it with the tolerance of other beneficial ingredients in the formula.