L-ascorbic acid is not advisable as it is unstable and requires several other stabilizers to function.
L-ascorbic acid decays the slowest. So the formula is more complicated than usual. This one is copied from the page
L-ascorbic acid Vitamin C type
L-ascorbic acid should not be directly mixed with water. due to oxidation and deterioration (To mix with water directly Should be used within 3 days) used to mix in cosmetics. If water is included, it should be added
Ferulic Acid and
Vitamin E to reduce oxidation (adding
Ferulic Acid and
Vitamin E to reduce oxidation is copyright of SkinCeuticals Please click to see how) or add
Glutathione (L-Reduced type) to reduce oxidation causing
L-ascorbic acid No loss
Derivative recommended
วิตามินซี that is easy to use, water soluble, for example
Ethyl Ascorbic acid,
Magnesium Ascorbyl Phosphate (MAP)