DIY Vitamin C Toner Formulation

Addressing your questions about modifying your L-ascorbic acid toner recipe:

Substituting Distilled Water with Distilled Witch Hazel

Yes, you can substitute distilled water with Witch Hazel (Distillate - Alcohol Free, Paraben Free). Since distilled witch hazel also has an acidic pH (typically between 3-5), it is compatible with L-ascorbic acid, which requires an acidic environment for stability. However, it is recommended to add Disodium EDTA at a concentration of 0.1-0.2% to chelate any metal ions present in the witch hazel that could destabilize the L-ascorbic acid.

Adding Glutathione for Stability

Yes, adding Glutathione (L-Glutathione) can help increase the stability of L-ascorbic acid due to its antioxidant properties. You can add it at a rate of 1-3%. For formulas specifically aiming to increase Vitamin C stability, a ratio of 1:10 (Glutathione to L-Ascorbic Acid) is suggested.

Storage and Shelf Life

Regardless of whether you add glutathione, the toner should be stored in the refrigerator (at 6-8°C) to maintain the stability of L-ascorbic acid. If you do not add glutathione, the mixture should ideally be used within 1-2 weeks. If you add glutathione and store it in the refrigerator, the shelf life can be extended to several months.

Remember that Vitamin C (L-ascorbic acid) is most effective but also least stable compared to other Vitamin C derivatives. Maintaining the correct pH (ideally between 2.0-4.0, but at least 3.5 for cosmetic products applied to the skin) and storing it properly are crucial for its efficacy and shelf life.