Hyaluronic Acid Powder (pH 2.0-3.5) — M.W < 50 K Da
Cosmetic Grade. The native acid form of hyaluronic acid — non-salt, protonated, and naturally acidic. Low molecular weight for deep penetration. The preferred starting material for chemical derivatization, acidic cosmetic formulations, and advanced HA-based actives. COSMOS, ISO, c-GMP, FDA, HALAL, KOSHER certified.
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Hyaluronic Acid Powder (pH 2.0-3.5, M.W < 50 K Da) is the native, non-salt form of one of nature's most remarkable biomolecules. Unlike the more common sodium hyaluronate (the sodium salt, pH 6.0-7.5), this is hyaluronic acid in its original protonated state — the exact molecular form found in the body's extracellular matrix before physiological buffering. Each disaccharide unit carries a free carboxylic acid group (-COOH) rather than the neutralized carboxylate (-COO−Na+), giving the powder its characteristic acidic pH of 2.0-3.5 in solution.
With a molecular weight under 50 K Da, this grade combines the deep-penetrating capability of low-MW HA with the unique chemical reactivity of the acid form. The free -COOH groups make it the preferred starting material for all HA chemical derivatization reactions: crosslinking (BDDE, PEG), acetylation, methacrylation (MA-HA), phenylboronic acid conjugation, and other modifications that are difficult or inefficient with the already-neutralized sodium salt. For formulators, it offers the flexibility to convert to sodium hyaluronate on-demand (simply neutralize) or use as-is in low-pH formulations (AHA serums, vitamin C products, acid peels) where the acidic pH is a feature, not a problem.
Technical Specifications
| Property | Specification |
|---|---|
| Product Name | Hyaluronic Acid Powder (Acid Form) |
| CAS Number | 9004-61-9 |
| Molecular Form | Native hyaluronic acid (protonated -COOH form, non-salt) |
| Molecular Weight | < 50 K Da (low molecular weight) |
| pH (0.1% aqueous solution) | 2.0 - 3.5 (acidic — NOT neutralized) |
| Appearance | White to off-white powder or granule |
| Purity (HPLC) | ≥98.0% |
| Glucuronic Acid Content | ≥44.0% |
| Loss on Drying | ≤10.0% |
| Protein Content | ≤0.1% |
| Heavy Metals | ≤10 ppm |
| Solubility | Soluble in water (forms acidic solution); neutralizable to NaHA with NaOH |
| Disaccharide Units | Approximately 125-250 |
| Grade | Cosmetic Grade |
| Certifications | ISO 9001, c-GMP, FDA, HALAL, KOSHER, COSMOS |
| Packaging | 100 g/bag, 500 g/bag, 1 kg/bag, 5 kg/bag (custom available) |
Hyaluronic Acid (HA) vs Sodium Hyaluronate (NaHA) — Complete Comparison
Both are hyaluronan, but the choice of form significantly impacts formulation, chemical reactivity, and product positioning:
🔬 Hyaluronic Acid (This Product)
- Chemical form: Protonated acid (-COOH)
- pH (0.1% sol.): 2.0 - 3.5
- Counterion: None (H+)
- INCI name: Hyaluronic Acid
- Neutralization: Required for neutral pH products
- Derivatization: Preferred — free -COOH reacts readily
- Acidic formulations: Perfect fit (AHA, vit C serums)
- Skin penetration: Slightly enhanced (protonated)
- Label appeal: "Hyaluronic Acid" (consumer recognition)
- Cost: Premium (specialty product)
💧 Sodium Hyaluronate
- Chemical form: Sodium salt (-COO−Na+)
- pH (0.1% sol.): 6.0 - 7.5
- Counterion: Sodium (Na+)
- INCI name: Sodium Hyaluronate
- Neutralization: Not needed — ready to use
- Derivatization: Less efficient — must protonate first
- Acidic formulations: Requires buffering
- Skin penetration: Good (dependent on MW)
- Label appeal: "Sodium Hyaluronate" (technical)
- Cost: Standard
Chemical Reactivity & Derivatization Advantage
The key advantage of the acid form over the sodium salt lies in its free carboxylic acid groups. In sodium hyaluronate, the -COO−Na+ groups are already neutralized and less reactive. In hyaluronic acid, the -COOH groups are available for direct chemical reaction — making it the essential starting material for all HA derivative synthesis:
Crosslinking
BDDE (1,4-butanediol diglycidyl ether), PEG, and divinyl sulfone crosslinkers react directly with -COOH groups. The acid form eliminates a deprotonation step and improves crosslinking efficiency for HA hydrogels, dermal fillers, and crosslinked HA powders.
Requires Acid FormMethacrylation (MA-HA)
Methacrylic anhydride reacts with HA's hydroxyl groups (-OH). The acid form's non-neutralized state prevents side reactions and yields higher degrees of methacrylation — critical for photo-crosslinkable HA hydrogels in 3D bioprinting and tissue engineering.
Research GradeAcetylation (AcHA)
Acetic anhydride acetylation of HA hydroxyls is more efficient with the acid form. Acetylated HA has enhanced lipophilicity and skin adhesion — a premium long-lasting moisturizing ingredient for high-end cosmetics.
Premium CosmeticsOther Conjugations
Phenylboronic acid, tyramine, hydrazide, and amine conjugations all proceed more efficiently with the acid form. The free -COOH enables carbodiimide coupling (EDC/NHS chemistry) without prior acidification — saving time and improving yields.
VersatileApplications & Use Cases
Low-pH Vitamin C Serums
Perfect for L-ascorbic acid serums (pH 2.5-3.5). The HA acid form works synergistically in this pH range — no buffering conflicts, deep penetration of both actives.
AHA/BHA Exfoliants
Glycolic, lactic, and salicylic acid formulations. HA in its native acid form is stable and active in low-pH environments where sodium hyaluronate would precipitate or lose efficacy.
HA Derivatization R&D
The required starting material for synthesizing crosslinked HA, MA-HA, AcHA, HA hydrogels, and all chemically modified HA derivatives for advanced biomaterials.
Deep-Penetrating Serums
At < 50 K Da with protonated -COOH, this HA penetrates deep into epidermis and partial dermis. Enhanced lipophilicity vs charged NaHA for transdermal delivery.
"Hyaluronic Acid" Label Products
Consumer brands wanting the exact INCI "Hyaluronic Acid" (not "Sodium Hyaluronate") on their ingredient list. Perceived as more natural/pure by consumers.
HA Research & Biology
Receptor binding studies (CD44, RHAMM, TLR4), enzymatic degradation assays, and HA biology research requiring the native unmodified acid form.
Conversion Guide — HA (Acid) to NaHA (Salt) On-Demand
One of the key advantages of purchasing the acid form is flexibility: you can use it as-is in acidic formulations, or convert it to sodium hyaluronate on-demand for neutral products. The conversion is straightforward:
| Step | Procedure | Notes |
|---|---|---|
| 1. Dissolve | Add HA powder to water with stirring (0.1-2.0% w/w) | Solution will be acidic (pH ~2.5-3.5). HA hydrates within 30-60 min at this MW. |
| 2. Neutralize | Add 0.1M NaOH dropwise with pH monitoring | Target pH 6.0-7.5. Each gram of HA requires approximately 2.5-3.0 mL of 0.1M NaOH for full neutralization. |
| 3. Buffer (Optional) | Add phosphate or citrate buffer to stabilize pH | Recommended for final formulations. 10-50 mM phosphate buffer, pH 6.5, is standard. |
| 4. Verify | Check pH, clarity, and viscosity | Solution should be clear, viscous, and pH-stable. Ready for incorporation into your formulation. |
Frequently Asked Questions
Hyaluronic acid (HA) is the native protonated form with free carboxylic acid groups (-COOH) and an acidic pH (2.0-3.5). Sodium hyaluronate (NaHA) is the sodium salt with neutralized carboxylate groups (-COO−Na+) and a near-neutral pH (6.0-7.5). HA is the premium choice for chemical derivatization, low-pH formulations, and brands wanting the native "hyaluronic acid" label name. NaHA is the standard choice for ready-to-use neutral cosmetic products. HA can be converted to NaHA on-demand by simple NaOH neutralization.
This is the natural pH of native hyaluronic acid. Each disaccharide repeating unit (D-glucuronic acid + N-acetyl-D-glucosamine) contains a carboxylic acid (-COOH) group on the glucuronic acid residue. This -COOH releases H+ ions in aqueous solution, producing the characteristic acidic pH. This is exactly how HA exists in the body before physiological buffering neutralizes it to ~pH 7.4. The low pH is not a defect — it is proof the product is genuine native HA, not the pre-neutralized sodium salt.
At the typical usage rate of 0.1-0.5%, the pH of the final formulation depends on the overall formula, not just HA. When incorporated into a properly formulated product (with pH adjusters, other ingredients, and water), the small amount of HA contributes minimally to the final pH. Many premium products are designed to work at low pH (vitamin C serums at pH 2.5-3.5, AHA products at pH 3.0-3.8), where HA's native acidity is synergistic, not problematic. For neutral-pH products, simply neutralize the HA solution before incorporation.
Yes, easily. Dissolve the HA powder in water, then add 0.1M NaOH dropwise while stirring until pH reaches 6.0-7.5. Each gram of HA requires approximately 2.5-3.0 mL of 0.1M NaOH. The -COOH groups deprotonate to -COO− and pair with Na+ ions, forming sodium hyaluronate. This gives you the best of both worlds: the chemical flexibility of the acid form for derivatization, and the option to create sodium hyaluronate on-demand.
The free -COOH groups in hyaluronic acid are significantly more reactive than the neutralized -COO−Na+ groups in sodium hyaluronate. For crosslinking (BDDE, PEG), esterification, amidation, methacrylation, and carbodiimide (EDC/NHS) coupling, the acid form eliminates a preliminary acidification step and generally achieves higher degrees of substitution. This is why research labs and manufacturers synthesizing HA derivatives (crosslinked HA, MA-HA, AcHA, HA-hydrogels) universally purchase the acid form as their starting material.
Yes. At < 50 K Da, this HA is small enough for deep epidermal and partial dermal penetration. The protonated acid form may offer slightly enhanced penetration compared to the charged sodium salt at the same MW, because uncharged -COOH groups are more lipophilic than charged -COO− groups. This makes it particularly valuable for anti-aging serums where deep HA delivery is desired, and for combination with low-pH penetration enhancers like AHAs.
ISO 9001:2015, c-GMP, FDA-registered, HALAL, KOSHER, and COSMOS certified. This product is Cosmetic Grade. Full Certificate of Analysis (COA), MSDS, pH verification data, and complete lot traceability documentation provided with every shipment.
Store at 15-25°C in a dry, dark place. Keep container tightly sealed — HA is hygroscopic and will absorb moisture. The acid form is chemically stable under proper storage conditions with a shelf life of 2-3 years. Unlike sodium hyaluronate, the acid form should not be stored in alkaline environments or with basic materials that could cause premature neutralization. Once dissolved in water, the solution should be used within 24-48 hours or preserved appropriately.