Four vitamin C derivatives, four different Korean limits
A brief that says "vitamin C 2%" leaves the factory to pick one of four raw materials. Korea's whitening list carries four vitamin C derivatives, and their specified levels run from 1% to 3%. Pure ascorbic acid is not on that list at all.
Four of the nine ingredients on Korea's whitening (brightening) functional-cosmetics list are vitamin C derivatives, and each carries its own specified level — 3-O-ethyl ascorbic acid at 1-2%, ascorbyl glucoside at 2%, ascorbyl tetraisopalmitate at 2% and magnesium ascorbyl phosphate at 3%. Pure ascorbic acid is not on the list. The four also differ in solubility and recommended pH, so the same percentage lands in a different formula depending on which name you write.
"Vitamin C 2%" is an instruction with the name missing
"Vitamin C 2%" may be the single most common line in an inbound brief. A factory receiving only that line has to choose among four raw materials, and the choice decides both what the label can claim in Korea and which formula the active can sit in.
Korea supports a whitening claim through a list of nine notified actives. Four of them are vitamin C derivatives, and their specified levels were never harmonised into one number. 3-O-ethyl ascorbic acid sits at 1-2%, ascorbyl glucoside and ascorbyl tetraisopalmitate at 2%, magnesium ascorbyl phosphate at 3%.
| Listed name (Korea) | Specified level | INCI on the label |
|---|---|---|
| 3-O-ethyl ascorbic acid | 1-2% | 3-O-Ethyl Ascorbic Acid |
| Ascorbyl glucoside | 2% | Ascorbyl Glucoside |
| Ascorbyl tetraisopalmitate | 2% | Ascorbyl Tetraisopalmitate |
| Magnesium ascorbyl phosphate | 3% | Magnesium Ascorbyl Phosphate |
The column to read is the middle one. "Vitamin C 2%" meets the specified level for three of the four, and falls a point short for magnesium ascorbyl phosphate. One sentence, two outcomes, depending on a name the brief did not include.
Pure ascorbic acid is not on the list
Plenty of detail pages lead with "pure vitamin C". The notified list, though, carries no entry called ascorbic acid. The vitamin C seats belong to the four derivatives above, and the remaining five go to niacinamide at 2-5%, arbutin at 2-5%, broussonetia extract at 2%, alpha-bisabolol at 0.5% and oil-soluble licorice extract at 0.05%.
None of this blocks pure ascorbic acid from a formula. Using an ingredient and using it as the basis of a claim are two separate questions. Match a listed active at its specified level and the product moves on the notification track; go off-list for the claim and a review dossier with its own timeline attaches. Settling that before the first sample keeps the schedule intact.
The same percentage does not fit the same formula
The four part ways at solubility. Magnesium ascorbyl phosphate is water soluble, and supplier specifications put it at 154g/L in water at 25C, roughly 15%. Ascorbyl tetraisopalmitate sits at the other end: technical data describes it as insoluble in water and soluble in oil, added to the oil phase.
| Material | Solubility | Supplier use level | pH as documented |
|---|---|---|---|
| Magnesium ascorbyl phosphate | Water soluble (154g/L at 25C) | 0.2-3%, up to 10% | Discolors below pH 6; 6.0-7.0 advised |
| 3-O-ethyl ascorbic acid | Both water and lipid listed | 0.15-15% | 5.0-6.0 recommended |
| Ascorbyl tetraisopalmitate | Oil soluble, water insoluble | 1-3% | No low-pH environment required |
| Ascorbyl glucoside | Dissolves directly in water | Not stated | 6.5-6.8 for long-term stability |
Those last two columns are where purchase decisions actually get made. Specify ascorbyl tetraisopalmitate for an aqueous toner and the formula cannot be built; put magnesium ascorbyl phosphate at 3% into an acidic essence and the formula sits in the discoloration range the supplier documents.
The cost a buyer rarely sees is the pH adjustment
This is where sample rounds slip. Ask for magnesium ascorbyl phosphate in a line already set below pH 5, and the factory chooses between lifting the pH above 6 or swapping the active. Lifting the pH moves the other actives and the sensory profile with it; swapping the active drops the specified level to 2%.
3-O-ethyl ascorbic acid is the roomier option here. Its technical data sheet puts a 3% aqueous solution at pH 4.0-5.5, recommends a formulation range of 5.0-6.0, and opens the use level to 0.15-15%. The CAS number is 86404-04-8, with room-temperature storage and 2-8C for long-term holding. For what is actually moving on the Korean shelf right now, see today's ingredient signal; to put levels and costs against it, use the product planner.
One caution: pH and use-level figures are exactly the fields that differ between suppliers. For magnesium ascorbyl phosphate alone, one source gives 5-7 and another 6.0-7.0. Before a purchase order, reconcile the numbers against the TDS for the lot you are actually buying.
Three lines for the purchase order
First, write the derivative with its INCI name: not "vitamin C 2%" but "Ascorbyl Glucoside 2%". Second, put the target formulation pH on the same line. Third, if the product will carry a whitening claim, state the specified level and the supplier use level separately so the factory does not read one as the other.
«Summary»
- Four of Korea's nine whitening actives are vitamin C derivatives, specified at 1-2%, 2% and 3%.
- Pure ascorbic acid is not on the list. Including it and claiming on it are different questions.
- Magnesium ascorbyl phosphate is water soluble and ascorbyl tetraisopalmitate is oil soluble, so the phase is decided before the percentage.
- Recommended pH runs from 5.0-6.0 to 6.5-6.8 depending on the material, which is why the formulation pH belongs in the brief.
*Sources: Korean whitening actives and levels — Nine whitening and four anti-wrinkle actives (Dr. Oracle) / 3-O-ethyl ascorbic acid — Vitamin C 3-O-Ethyl Ascorbic Acid TDS (Avena Lab) / magnesium ascorbyl phosphate — Vitamin C MAP fact sheet (MakingCosmetics), Magnesium Ascorbyl Phosphate (Lotioncrafter) / ascorbyl tetraisopalmitate — Ascorbyl Tetraisopalmitate INCI profile (SpecialChem), Ephyla Vit C TetraE overview / ascorbyl glucoside pH — Liquid AA2G serum Q&A (MySkinRecipes). Checked 11 November 2026.*
Using vitamin C in a Korean private label formula
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Questions people ask
The raw material itself. Depending on which of the four listed derivatives the factory picks, the specified level is either 1-2%, 2% or 3%, and the INCI name on the label changes with it. Write the derivative name on the sample request.
Not through the listed-ingredient route. Ascorbic acid does not appear among the nine whitening ingredients; only the four derivatives do. An off-list active means a full review dossier instead of a notification.
Magnesium ascorbyl phosphate is water soluble, dissolving up to 154g/L in water at 25C. Ascorbyl tetraisopalmitate is insoluble in water and goes into the oil phase. Supplier data for 3-O-ethyl ascorbic acid lists both water and lipid solubility.
Because the recommended window differs by material. Magnesium ascorbyl phosphate is documented to discolor below pH 6, while supplier data puts 3-O-ethyl ascorbic acid at pH 5.0-6.0. An acidic toner base pushes the first one out of its range.
No. Suppliers list magnesium ascorbyl phosphate at 0.2-3% (up to 10%), 3-O-ethyl ascorbic acid at 0.15-15% and ascorbyl tetraisopalmitate at 1-3%. The Korean figure exists to support a label claim; the supplier range describes what the formula can carry.