INCI Name
Ascorbic Acid
Functions
2 Roles
Sustainability
8/10
Category
antioxidants
What It Does
Ascorbic Acid is the purest and most potent form of Vitamin C, typically produced through fermentation of glucose. As a water-soluble antioxidant with a highly acidic pH (2-3), it's notoriously unstable in aqueous solutions and requires careful formulation with pH control, antioxidant stabilizers like ferulic acid or vitamin E, and often anhydrous or low-water systems. Formulators choose L-ascorbic acid specifically because it's the only form of vitamin C proven to penetrate skin effectively at concentrations of 10-20%, where it stimulates collagen synthesis, inhibits melanin production, and neutralizes free radicals, though its instability has led to the development of more stable derivatives like ascorbyl glucoside and magnesium ascorbyl phosphate.
Technical Properties
pH Range
2.0-3.0
Optimal working range
Ionic Charge
anionic
Molecular charge type
Viscosity Effect
neutral
Impact on formula thickness
Molecular Profile
Molecular Weight
176.12
g/mol
LogP
-1.60
Partition coefficient (lipophilicity)
H-Bond Donors
4
Hydrogen bond donor count
H-Bond Acceptors
6
Hydrogen bond acceptor count
Polar Surface Area
107.0
Angstroms squared
Ingredient Compatibility
Known Interactions
Benzoyl Peroxide oxidizes L-Ascorbic Acid, rendering both ingredients inactive. These must never be combined.
Hydrogen Peroxide rapidly oxidizes Ascorbic Acid, deactivating both. Strong oxidizer + antioxidant neutralization.
Ascorbic Acid reduces Cu2+ to Cu1+, deactivating copper peptides and generating free radicals via Fenton-like reactions. These must not be combined.
Ascorbic Acid reduces Cu2+ in GHK-Cu to Cu1+, deactivating the peptide complex and generating reactive oxygen species. Never combine in the same formulation.
Niacinamide and L-Ascorbic Acid can interact at low pH, potentially forming nicotinic acid (causes flushing). They work optimally at different pH ranges (Niacinamide pH 5-7, Ascorbic Acid pH 2.5-3.5). Consider using a Vitamin C derivative stable at higher pH, or separate products.
Retinol and L-Ascorbic Acid both require low pH but Retinol is unstable in acidic conditions. Using both in the same formula reduces efficacy of both actives. Separate into AM (Vitamin C) and PM (Retinol) products.
Ascorbic Acid can degrade Cyanocobalamin (Vitamin B12) in solution, converting it to inactive analogues. In liquid/gummy formulations, use Methylcobalamin or separate the vitamins. Tablet/capsule forms are less affected.
Ascorbic Acid + Sodium Benzoate can form benzene (a carcinogen) in acidic conditions with heat or UV exposure. This is a well-documented FDA concern in beverages. Use alternative preservatives or ensure pH > 4 and avoid metal catalysts.
Sodium Hyaluronate may thin in viscosity at the low pH required for L-Ascorbic Acid (pH < 3.5). Consider using a lower molecular weight HA or a Vitamin C derivative stable at higher pH.
Iron from iron oxide pigments can catalyze oxidation of Ascorbic Acid via Fenton reaction. Not a concern at typical pigment levels in tinted products, but avoid high concentrations of both.
Arbutin is most stable and effective at pH 5-7, while L-Ascorbic Acid requires pH 2.5-3.5. Combined use forces a pH compromise that reduces efficacy of one or both. Use an Ascorbic Acid derivative if combining.
Ascorbic Acid can accelerate Thiamine (B1) degradation in solution at acidic pH. In liquid supplements, this can reduce B1 potency over shelf life. Dry forms are unaffected.
Sustainability Profile
Sustainability Score
Biodegradability
readily biodegradable
Source
fermentation
Feedstock
glucose from corn or wheat
Related Ingredients
Similar antioxidants to explore
Quick Reference
- Full INCI Name
- Ascorbic Acid
- Common Name
- Vitamin C
- CAS Number
- 50-81-7
- Category
- antioxidants