Formula Review

Thank you for providing your formula. This formulation includes several beneficial ingredients, particularly Vitamin C (L-ascorbic acid), Ferulic Acid, and Vitamin E, which are known for their antioxidant and skin-brightening properties.

However, there are a few points to consider regarding this formula:

• Vitamin C Stability and pH: L-Ascorbic Acid is most effective and stable at a low pH, typically between 2.0 and 4.0. While your formula includes L-Ascorbic Acid at a good concentration (15%), the presence of water and Triethanolamine (which increases pH) can significantly impact its stability and efficacy. Triethanolamine is used to raise pH, which might counteract the low pH needed for L-Ascorbic Acid. It is crucial to ensure the final pH of the formula is within the optimal acidic range for L-Ascorbic Acid.
• Ethoxydiglycol Concentration: The concentration of Ethoxydiglycol in your formula is 20%. Based on typical cosmetic guidelines, the recommended usage rate for Ethoxydiglycol in leave-on products is significantly lower (e.g., not more than 2.6% according to the product description provided). Using it at 20% may exceed safety limits and could potentially cause skin irritation.
• Formulation Type: The inclusion of Laureth-23, an emulsifier, suggests this formula is intended to be an emulsion (like a lotion or cream) rather than a simple serum, especially since it contains both water-soluble and oil-soluble components (like Vitamin E).
• Preservation: Phenoxyethanol at 0.5% is a common preservative concentration, but it is less effective against fungi. Depending on the final product type, packaging, and manufacturing process, you might need to consider a broad-spectrum preservative system to ensure microbial stability.

Recommendations:

1. Adjust Ethoxydiglycol: It is highly recommended to reduce the concentration of Ethoxydiglycol to be within the safe and recommended usage limits for leave-on products.
2. Review pH Adjustment: Carefully check and adjust the final pH of the formula to be between 2.0 and 4.0 to ensure the stability and effectiveness of L-Ascorbic Acid. Consider using acidic pH adjusters if needed, and re-evaluate the use of Triethanolamine if it raises the pH too high.
3. Consider Vitamin C Stability: Given the water content, explore additional methods to enhance L-Ascorbic Acid stability, such as using chelating agents or specific stabilizing technologies if needed.
4. Evaluate Preservation: Assess the preservation system based on the final formula composition and packaging to ensure adequate protection against both bacteria and fungi.

Overall, while the formula contains potent actives, adjusting the Ethoxydiglycol level and optimizing the pH for Vitamin C stability are important steps to improve both safety and efficacy.