Ingredients
Vitamin C
How vitamin C is formulated for brightening and antioxidant products: the stability problem, derivative forms, and the Gluta-C and ethyl ascorbic acid systems.
Vitamin C (ascorbic acid) is a widely used brightening and antioxidant active whose main formulation challenge is instability - it oxidises in water, light and air and loses activity. Formulators respond with stabilised systems and derivatives. Celcode works with Gluta-C, which combines ascorbic acid with glutathione and gold sub-microparticles to protect it, and with ethyl ascorbic acid, a stable derivative designed to inhibit melanin production directly. Base, pH, antioxidants and airless, light-protective packaging complete the stabilisation.
The stability problem
Ascorbic acid is water-soluble, acidic and easily oxidised. In a water-based product it degrades on contact with oxygen, light and heat, and the rate rises with pH. A vitamin C product that has lost activity often looks the part - yellow to brown - but no longer does its job. Formulation of vitamin C is therefore mostly about protection: choosing a form that resists oxidation, a base and pH that suit it, antioxidants that spare it, and packaging that keeps air and light out.
Forms of vitamin C
| Form | Character | Formulation notes |
|---|---|---|
| L-ascorbic acid | The pure, most-studied form; potent antioxidant and tyrosinase inhibitor | Needs a low pH and careful stabilisation; anhydrous or low-water systems and airless packaging are common |
| Ethyl ascorbic acid (3-O-ethyl ascorbic acid) | A stable derivative that penetrates well and inhibits melanin production directly | Stable across a wider pH range; works at low concentrations |
| Ascorbyl glucoside | A stable glycoside derivative | Converts to ascorbic acid in the skin; milder; often used at higher levels |
| Magnesium ascorbyl phosphate, sodium ascorbyl phosphate | Stable salt derivatives, water-soluble | Gentle; suit sensitive-skin products; need enzymatic conversion in skin |
| Oil-soluble esters (for example tetrahexyldecyl ascorbate) | Lipophilic derivatives | Suit creams and oil-based serums; stable in anhydrous bases |
The systems Celcode works with
| System | What it is | How it is designed to work | Supplier evidence (raw material, supplier test conditions) |
|---|---|---|---|
| Gluta-C | Ascorbic acid combined with glutathione and gold sub-microparticles | Glutathione counteracts ascorbic acid’s pro-oxidant activity and the sub-microparticles protect it, so more active reaches the skin in a light, non-sticky formulation; aimed at brightening, evening skin tone, collagen support and protection against UV, ozone, pollution and blue light | Supplier data report better antioxidant efficacy than free ascorbic acid and ascorbic acid derivatives (DPPH assay), superior protection against UVA lipoperoxidation in vitro even at lower ascorbic acid levels, up to 70% better environmental protection, and stability for 6 months at 40 °C |
| Ethyl ascorbic acid | A highly stable derivative of vitamin C | Inhibits tyrosinase and melanin monomer polymerisation directly, without needing enzymatic conversion, and stimulates collagen synthesis; higher skin penetration in its acid form at pH 4.5 | Supplier data report stronger inhibition of melanogenesis at 0.1% than magnesium ascorbyl phosphate at 0.3% and ascorbyl glucoside at 0.2%, and about 10 times the penetration of magnesium ascorbyl phosphate |
Ingredient data on this page is supplied by the ingredient manufacturers and refers to the raw material under their test conditions. It informs the choice of an active; it is not a claim for any Celcode product. Claims for a finished product are substantiated for that product and worded within cosmetic scope at the regulatory check.
Formulation considerations
- pH. Each form has a pH window; the base, the buffer system and the other actives are set to keep the product in it over its shelf life.
- Water activity. Low-water or anhydrous bases protect ascorbic acid; water-based serums rely on derivatives or protected systems.
- Antioxidant partners. Vitamin E, ferulic acid and glutathione are used to spare vitamin C from oxidation.
- Packaging. Airless pumps, opaque or amber containers and single-dose ampoules limit oxygen and light exposure (packaging).
- Stability testing. Vitamin C content and colour are tracked during stability testing, which sets the shelf life and any period-after-opening guidance.
- Claims. Brightening, antioxidant and radiance claims are worded within cosmetic scope; protection claims against UV are sun-protection claims with their own testing requirements (regulatory support).
Product formats
Vitamin C is most often formulated as a serum or ampoule, in creams and masks, and in professional brightening ranges. It is frequently combined with the actives on the brightening solutions page.
Download
The vitamin C solutions brochure (PDF, 0.9 MB) contains the supplier diagrams and study summaries behind this page. All brochures are listed on the brochures page.
Frequently asked questions
Why do vitamin C serums turn yellow or brown?
Ascorbic acid oxidises to dehydroascorbic acid and further breakdown products, which are coloured and less active. Water, oxygen, light, heat and a pH that is too high all speed this up. Stabilised systems, derivatives, antioxidants and protective packaging slow it down.
Which form of vitamin C is best?
It depends on the product. L-ascorbic acid is the most studied but the least stable and needs a low pH. Derivatives such as ethyl ascorbic acid trade some potency for much better stability and gentler pH. Protected systems such as Gluta-C aim to keep ascorbic acid active in a lighter formulation. The brief, the base and the packaging decide.
Can vitamin C be combined with other actives?
Vitamin C is commonly paired with vitamin E and ferulic acid as antioxidants, and with hydrating actives. Combinations with actives that need a different pH, or with certain metals, are checked for compatibility during formulation.
- Written by
- Celcode Dermal Lab
- Published
- Updated