Kojic Acid Stability with L-Ascorbic Acid: pH and Oxidation
คำถาม
I am formulating a product using Kojic Acid and plan to include L-Ascorbic Acid at 15%. Could you please advise on the suitable pH range for Kojic Acid and how to maintain stability, especially regarding oxidation, when combining it with L-Ascorbic Acid? Are there any specific formulation techniques or additives, like Vitamin E, that can help?
คำตอบ
Kojic Acid Stability with L-Ascorbic Acid
Regarding the stability of Kojic Acid when mixed with L-Ascorbic Acid, the recommended pH range for the Kojic Acid available on our website is 4.0-7.0, not 4.5-9.0 as you initially mentioned.
Mixing Kojic Acid with L-Ascorbic Acid at a concentration of 15% would likely result in a pH lower than 4.0, which is outside the stable range for Kojic Acid. To address this, it is recommended to reduce the concentration of L-Ascorbic Acid to approximately 10% to help maintain the pH above 4.0.
Kojic Acid is prone to oxidation, especially when exposed to sunlight. To improve its stability and extend the shelf life of your formulation, consider these approaches:
- For water-based (oil-free) formulas: The mixture should ideally be used within 2 weeks. Store the product in the refrigerator and avoid exposure to sunlight.
- For cream formulas (containing oil): Adding Vitamin E Tocopherol (such as dl-alpha tocopherol) can help to slow down the oxidation process of Kojic Acid.
By adjusting the L-Ascorbic Acid concentration and incorporating these stability measures, you can create a more stable formulation containing both Kojic Acid and L-Ascorbic Acid.
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Vitamin E (dl-alpha tocopherol)
