Vitamin C, E, Ferulic Acid Serum Formulation: Ingredient Substitution, Texture, and pH

Question

Based on my formula (containing L-Ascorbic Acid, Vitamin E, Ferulic Acid, etc.), I have some questions: Can I add Lactic Acid, and what are its effects on the formula, especially pH and potential irritation? Can I substitute Vitamin E Acetate for d-alpha tocopherol? What are the differences in anti-oxidation effectiveness and clarity? If I use Xanthan Gum at 1%, will the texture be a liquid gel or a full gel? How should I adjust the percentage for a different consistency? How should Xanthan Gum be mixed? What are the important mixing steps, especially for dissolving ingredients like Ferulic Acid? When should I adjust the pH, and what is the suitable pH range for this type of formula, considering efficacy and FDA regulations (pH >= 3.5)?

MySkinRecipes Expert · Accepted Answer

Formula Feedback

Based on your formula and the feedback provided:

Formula Viability: The formula can generally be used, but be aware that combining L-Ascorbic Acid and potentially Lactic Acid will result in a low pH, which can cause skin irritation.
Lactic Acid: Adding Lactic Acid is possible, but it will further lower the pH and increase the potential for irritation. Lactic Acid is used for exfoliation and moisturization, but its effectiveness is pH-dependent, ideally below 4.0.
Vitamin E: You must replace Vitamin E Acetate with d-alpha tocopherol. Vitamin E Acetate has lower purity and is likely to make your formula cloudy. More importantly, d-alpha tocopherol is the highest quality type with proven anti-oxidation effectiveness in this type of formula, whereas the efficacy of Vitamin E Acetate for this purpose is not as well-established.
Xanthan Gum: Using Xanthan Gum at 1% will create a full gel texture, not a liquid gel. Adjust the percentage if you desire a different consistency. Xanthan Gum acts as a thickener and can be mixed into the water phase.
Mixing Instructions: It is crucial to follow the original mixing steps, especially for dissolving ingredients like Ferulic Acid, which typically requires a solvent such as Ethoxydiglycol. Ferulic Acid is a powerful antioxidant that works synergistically with Vitamin C and E.
pH Adjustment: You can adjust the pH of the formula in the final step after all ingredients are mixed. For L-Ascorbic Acid formulas, the pH should ideally be between 2.0-4.0 for efficacy, but FDA regulations require cosmetics applied to the skin to have a pH of at least 3.5.

To summarize, the main necessary change is replacing Vitamin E Acetate with d-alpha tocopherol. Be mindful of the potential for irritation due to the low pH from L-Ascorbic Acid and Lactic Acid.