★What is the difference between Sodium Ascorbyl Phosphate (SAP) and L-Ascorbic Acid (pure Vitamin C)?
L-Ascorbic acid is a potent antioxidant but highly unstable — it oxidizes rapidly in water, turns yellow/brown, and often causes stinging at low pH. SAP is a stable, water-soluble derivative that converts to vitamin C on the skin via enzymatic hydrolysis. It is non-irritating (neutral pH), does not discolor, and remains active for months in formulations. While SAP is slightly less potent on a molar basis, its stability and gentleness make it ideal for sensitive skin, long-shelf-life products, and clear serums.
★What is the difference between SAP and Magnesium Ascorbyl Phosphate (MAP)?
Both are stable vitamin C derivatives, but they differ in counterion (sodium vs. magnesium). Key differences:
Solubility: Both are water-soluble; SAP dissolves slightly faster.
pH optimum: SAP works best at pH 5.0–7.0, MAP at pH 6.0–7.0.
Skin feel: SAP leaves a slightly smoother, less tacky residue than MAP.
Conversion rate: Some studies suggest SAP converts to vitamin C more efficiently on skin, but both are effective.
Cost: SAP is generally more cost-effective.
We offer both and can help you choose based on your formula.
★Is SAP stable in water-based formulations? What pH range is best?
Yes, SAP is very stable in water. It remains stable at pH 5.0–7.0 (optimal 5.5–6.5). Avoid pH <4.0 or >8.0, as the phosphate ester bond may hydrolyze. SAP does not require special antioxidants or chelators, but standard preservatives are recommended. It tolerates processing temperatures up to 60°C.
★What is the appearance and purity of your Sodium Ascorbyl Phosphate?
It appears as white or off-white crystalline powder, with purity ≥ 98%, low impurity and stable batch consistency.
★Is Sodium Ascorbyl Phosphate water-soluble or oil-soluble?
Sodium Ascorbyl Phosphate has excellent water solubility, easy to be added to water-phase formulas like essences, toners and lotions.
★What skincare products is Sodium Ascorbyl Phosphate suitable for?
Whitening essences, oil-control acne creams, brightening toners, acne repair serums, sun repair products, firming masks and sensitive skin care products.
★What is the recommended usage rate of Sodium Ascorbyl Phosphate?
Recommended addition concentration: 1%–5%, adjusted according to product positioning (acne care can use moderate concentration).
★What pH range is suitable for Sodium Ascorbyl Phosphate?
Sodium Ascorbyl Phosphate is stable and effective in pH 6.0–8.0 (neutral to slightly alkaline), which is conducive to maintaining its activity.
★What ingredients can Sodium Ascorbyl Phosphate be compounded with?
It can be compounded with niacinamide, salicylic acid, hyaluronic acid, tranexamic acid, ceramides and anti-acne ingredients to enhance efficacy.
★Is Sodium Ascorbyl Phosphate approved for cosmetic use in the EU, USA, and China?
EU: Listed in CosIng (INCI: Sodium Ascorbyl Phosphate) as a permitted cosmetic ingredient with no concentration restriction (typical use 0.5-5%).
USA: Allowed; generally recognized as safe (GRAS) for topical use.
China (NMPA): Listed in IECIC 2021 (INCI: 抗坏血酸磷酸酯钠) with no maximum concentration specified, but typical use ≤5%.
We provide full registration documents including COA, MSDS, TDS, and China compliance declaration.
