| HS Code | 169720 |
| Product Name | Sodium D-aspartate |
| Chemical Name | D-Aspartic acid sodium salt monohydrate |
| Synonym | Monosodium D-aspartate monohydrate; H-D-Asp-ONa·H2O |
| Cas Number | 21059-47-2 |
| Molecular Formula | C4H6NNaO4·H2O |
| Molecular Weight | 173.10 g/mol |
| Appearance | White crystalline powder |
| Assay Purity | ≥98% (typical) |
| Solubility | Soluble in water; practically insoluble in ethanol and ether |
| Melting Point | ~230 °C (decomposition) |
| Optical Rotation | [α]20/D ≈ -21° (c = 5, 6 M HCl) |
| Ph | 6.0–7.5 (1% aqueous solution) |
| Storage Conditions | Store in a cool, dry, airtight container; protect from moisture and light |
| Chirality | D-enantiomer |
| Hazard Safety | May cause eye/skin irritation; handle with appropriate laboratory protection |
As an accredited Sodium D-aspartate factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sodium D-aspartate is supplied in 25 kg net quantity, packed in fiber drums with double polyethylene liners for safety. |
| Container Loading (20′ FCL) | 20′ FCL: Sodium D-aspartate packed in 25kg drums or palletized bags, securely loaded and ventilated for safe transport. |
| Shipping | Sodium D-aspartate is typically shipped as a non-hazardous chemical, not regulated as dangerous goods. Pack in sealed polyethylene bags inside fiber drums or HDPE containers to protect against moisture. Transport at ambient temperature, avoid dust generation, and keep away from strong acids and oxidizers. Follow standard chemical handling and local transport regulations. |
| Storage | Store Sodium D-aspartate in a tightly sealed container in a cool, dry, well-ventilated area away from moisture, heat, and direct light. Keep at room temperature and avoid exposure to strong acids or oxidizing agents. Ensure the container is clearly labeled and protected from physical damage. |
| Shelf Life | Shelf life is typically 2 years when stored tightly sealed in a cool, dry place away from light. |
In hard-shell dietary supplement manufacturing, sodium D-aspartate is incorporated as an anhydrous free-flowing salt rather than the free acid when a water-soluble, highly dispersible oral solid form is required. The ingredient is released for use against a chiral purity specification of not less than 98.0% D-enantiomer by chiral HPLC according to USP <621>, with L-aspartate not more than 1.0%, residue on ignition not more than 0.1%, and lead, cadmium, arsenic, and mercury limits verified by USP <2232>. On an anhydrous basis, 155.09 g sodium D-aspartate contains 133.10 g D-aspartic acid; the equivalence factor of 0.858 is used when the label claim is expressed as D-aspartic acid. A serving delivering 2.0 g D-aspartic acid therefore requires 2.33 g sodium D-aspartate, which contributes approximately 345 mg sodium and must be accounted for in the Supplement Facts sodium declaration under 21 CFR 101.36. In a dry pre-mix at 78.0 wt% sodium D-aspartate, the total powder bed per serving is 2.99 g; this can be filled into five 00-size two-piece gelatin or HPMC capsules at 598 mg nominal fill weight or compressed into a 1,500 mg tablet using a rotary press with 15–25 kN precompression and 45–65 kN main compression. The powder is screened through a 20-mesh stainless-steel screen, blended in a 300 L bin blender for 20 min at 12 rpm, and transferred to a dosator-style capsule filler maintained at 25–35% RH. At relative humidity above 60%, the salt requires pre-drying at 40°C for 4–6 h in a vacuum tray dryer because hygroscopic uptake above 2.0 wt% causes bridging and stick formulations to fail weight-variation testing under USP <2091>. Final dosage forms are hard-shell dietary supplement capsules and direct-compression tablets for sports nutrition markets requiring NSF/ANSI 173 or Informed Sport certification.
| Sodium D-Aspartate Loading (wt%) | Excipient System | Total Blend per Serving (g) | D-Aspartic Acid Equivalent per Serving (g) |
|---|---|---|---|
| 78.0 | Pregelatinized starch 20.0, fumed silica 2.0 | 2.99 | 2.00 |
| 65.0 | Microcrystalline cellulose PH-102 32.0, croscarmellose sodium 2.0, magnesium stearate 1.0 | 3.58 | 2.00 |
| 50.0 | Maltodextrin M100 47.0, silicon dioxide 2.0, magnesium stearate 1.0 | 4.66 | 2.00 |
Effervescent stick packs and water-dispersible drink mixes impose a separate set of granulation controls because sodium D-aspartate is hygroscopic and can initiate premature acid-carbonate interaction if residual moisture exceeds 0.5 wt% by Karl Fischer titration. In a 20.0 g serving targeting 2.0 g D-aspartic acid, sodium D-aspartate anhydrous is added at 12.5–15.0 wt%; the acid-carbonate couple consists of citric acid anhydrous at 28–32 wt% and sodium bicarbonate at 34–38 wt%, with 1.5 wt% polyvinylpyrrolidone K90 as granulation binder and 1.0 wt% polyethylene glycol 6000 as lubricant. The ratio of citric acid to sodium bicarbonate is maintained between 1:1.2 and 1:1.35 to achieve complete acid neutralization without excess tartness. Compliance for the effervescent dosage form refers to Ph. Eur. 10.0, 0478 for effervescent tablets and EU Directive 2002/46/EC for food supplements in the European Union; where the product is marketed in the United States, labeling follows 21 CFR 101.36 and manufacturing follows 21 CFR Part 117.
Acid and carbonate phases are granulated separately in a top-spray fluidized-bed unit fitted with a 50 kg product bowl, inlet air temperature 40–50°C, dew point −20°C. Sodium D-aspartate is milled through a 0.8 mm conical screen, dry blended with sodium bicarbonate, maltodextrin, and flavor in a 200 L tumble blender at 6 rpm for 10 min, and then mixed with the acid granulate in a final 5 min step. The final mix is packed on a vertical form-fill-seal machine set to 20% RH or lower, with a 1.0 g silica gel desiccant sachet in each stick pack. Accelerated stability is tracked at 40°C/75% RH for 6 months in aluminum foil stick packs with 9 µm foil thickness; hardness of effervescent tablets is maintained at 80–120 N and disintegration time below 3 min in 250 mL water at 20°C. Finished product types include 4.0–5.0 g effervescent tablets and 20.0 g stick pack drink powders.
Because the sodium counterion does not participate in the Eschweiler–Clarke methylation used to produce N-methyl-D-aspartic acid, sodium D-aspartate is first dissolved in purified water and adjusted to pH 3.0–3.5 with hydrochloric acid to liberate D-aspartic acid; the solution is then charged with formic acid and aqueous formaldehyde for reductive methylation. The charging ratio is 1.0–1.2 mol sodium D-aspartate per 1.0 mol of limiting methylating agent; published data for this specific configuration is limited, and the optimal stoichiometry changes with reactor headspace, agitation rate, and off-gas removal capacity. The reaction mass is held at 65–80°C for 16–24 h in a 1,000 L glass-lined reactor with PTFE baffles and a reflux condenser. Formaldehyde off-gas is routed to a 5 wt% sodium hydroxide scrubber before release. Release as a pharmaceutical intermediate is governed by ICH Q7 for GMP documentation, ICH Q3C R8 for residual solvent limits, ICH Q3D for elemental impurities, and USP <467> as the compendial method for residual solvents. Process validation batches must demonstrate residual formaldehyde below the compendial limit, residual formic acid below the permitted daily exposure, and no more than 0.1% sodium chloride carryover into the isolated product.
| Regulatory/Compendial Reference | Scope | Batch Release or Audit Control Point |
|---|---|---|
| ICH Q7 | API GMP | Master batch record, deviation, change control |
| ICH Q3C R8 | Residual solvents | Headspace GC, Class 2 reporting |
| ICH Q3D | Elemental impurities | ICP-MS after acid digestion |
| USP <467> | Residual solvent method | Headspace GC |
| ISO 14001:2015 | Environmental management | Wet scrubber pH, conductivity |
Isolated product is crystallized from methanol/water at 0–5°C, filtered through a 0.45 µm polypropylene cartridge, and dried in a vacuum tray dryer at 45°C for 8–12 h to a final moisture content below 1.0 wt%. Enantiomeric purity of isolated N-methyl-D-aspartic acid is specified as not less than 98.0% D-isomer; residual unreacted D-aspartic acid is not more than 1.0% by anion-exchange HPLC with UV detection at 210 nm. Finished product types include N-methyl-D-aspartic acid monohydrate reference standards and chiral building blocks for NMDA receptor pharmacology research.
When chemically defined basal media are prepared for neuroendocrine cell lines and steroidogenesis studies, sodium D-aspartate is introduced at 0.05–0.5 mM to provide a defined D-isomer pool; published production-scale bioprocessing data for this specific configuration is limited, and media optimization is performed on a cell-line-specific basis. Raw material release for cell culture use includes bioburden below 100 CFU/g and endotoxin below 0.25 EU/mg. The salt is dissolved in WFI-grade water at 25–35°C under nitrogen overlay, adjusted to pH 7.0–7.4 with 1 M sodium hydroxide, and sterile-filtered through a 0.22 µm PVDF membrane in an ISO 14644-1 Class 5 cleanroom. The filtered concentrate is transferred into single-use bioprocess bags and either frozen at −20°C or lyophilized at −40°C shelf, 100–120 mTorr vacuum, primary drying at −20°C for 24 h, and secondary drying at 20°C for 6 h. Compliance is maintained under ISO 13485:2016 for research-use-only raw material supply, ISO 20387:2018 for biobanking where applicable, and endotoxin release tested per Ph. Eur. 2.6.14 with acceptance below 0.25 EU/mg. Finished product types include liquid media supplements, lyophilized cell culture media components, and research-grade amino acid standards for in vitro steroidogenesis models.
In enzymatic assay kits intended for D-aspartate quantification in human plasma, tissue homogenates, and fermentation media, sodium D-aspartate functions as the substrate for D-aspartate oxidase (EC 1.4.3.1). In reagent formulation, the substrate is filled into glass vials at 0.1–1.0 mM after reconstitution in 50 mM Tris-HCl buffer, pH 8.0, with 4–8% (w/v) mannitol and 0.1% trehalose as lyoprotectants. The filled vials are partially stoppered and loaded into a shelf lyophilizer with −45°C freezing, 80–100 mTorr chamber pressure, primary drying at −25°C for 12–18 h, and secondary drying at 25°C for 4–8 h. Residual moisture is verified by Karl Fischer titration at ≤1.0 wt%. Linearity is validated over 0.05–2.0 mM D-aspartate, with intra-assay CV below 5.0% and inter-assay CV below 10.0% across three lots; substrate blank is prepared in 50 mM Tris-HCl with 0.05% sodium azide. Lyophilized substrate vials are stored at 2–8°C and demonstrate less than 10% activity loss after 12 months when moisture ingress is kept below 0.1% water vapor transmission rate. Compliance is governed by ISO 13485:2016 for IVD reagent manufacturing and Regulation (EU) 2017/746 for European market access; risk management follows ISO 14971:2019. Finished product types include lyophilized enzyme substrate vials, 96-well microplate assay kits, and screen-printed biosensor chips.
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Sodium D-aspartate is the monosodium carboxylate of D-aspartic acid, supplied as a white to off-white crystalline powder with the anhydrous formula C4H6NNaO4 and a formula weight of 155.08 g/mol. The product is commonly specified in three configurations: an anhydrous pharmaceutical-intermediate grade, a monohydrate crystalline grade with water content 10.0–11.5% (C4H6NNaO4·H2O, 173.10 g/mol), and a certified analytical standard. Selection among these configurations is controlled by water content, enantiomeric purity, residual solvent profile, and residue on ignition rather than by a standardized model number. A representative certificate-of-analysis matrix is given below.
| Parameter | Anhydrous grade | Monohydrate grade | Analytical standard |
|---|---|---|---|
| Appearance | White to off-white crystalline powder | White crystalline powder | White crystalline powder |
| Assay by HPLC | ≥99.0% | 98.0–101.0% on anhydrous basis | ≥99.5% |
| Enantiomeric excess by chiral HPLC | ≥99.0% | ≥99.0% | ≥99.5% |
| Water content by Karl Fischer (USP <921>) | ≤0.5% | 10.0–11.5% | ≤0.5% |
| Residue on ignition (USP <281>) | ≤0.1% | ≤0.1% | ≤0.05% |
| pH of 1% aqueous solution | 7.0–8.0 | 7.0–8.0 | 7.0–8.0 |
| Residual solvents by USP <467> | Ethanol ≤0.1% | Ethanol ≤0.1% | Ethanol ≤0.05% |
Industrial material is typically produced by D-selective enzymatic resolution of synthetic DL-aspartic acid or by diastereomeric salt resolution followed by neutralization with sodium hydroxide and crystallization from aqueous ethanol. The monohydrate form is obtained by controlled crystallization, while anhydrous product is dried under vacuum. Lot-to-lot variability in residual ethanol, particle size, and water content affects downstream milling, dry blending, and coupling efficiency. Purchasers often specify release testing beyond supplier default limits when the material is intended for chiral peptide synthesis or for sensitive cell-based assays.
Enantiomeric purity is the critical quality attribute for sodium D-aspartate because the L-enantiomer can act as a process impurity that is difficult to purge once incorporated into a peptide or derivatized intermediate. Chiral HPLC with a teicoplanin-based chiral stationary phase is employed for routine release testing, with UV detection at 210 nm. Derivatization with Marfey’s reagent, followed by reversed-phase HPLC at 340 nm, is also used to resolve D- and L-aspartate in complex reaction mixtures. The free acid liberated from the sodium salt shows a specific rotation of approximately -24° to -25° in 6 N HCl; however, polarimetry alone is not accepted as a release method for the salt because hydration and counterion content alter the observed rotation. Acceptance limits typically require an enantiomeric excess of ≥99.0% and L-aspartate content of ≤0.5%. For analytical-standard grade, the L-enantiomer limit is tightened to ≤0.2%.
In pharmaceutical intermediate processing, the D-aspartate backbone is converted into N-protected derivatives such as N-Boc-D-aspartic acid α-benzyl ester, N-Fmoc-D-aspartic acid β-tert-butyl ester, or D-aspartic acid α-methyl ester hydrochloride. These transformations require water control in the anhydrous grade below 0.5% because residual moisture hydrolyzes activated ester intermediates during carbodiimide-mediated coupling. If the monohydrate form is used, vacuum drying at 40–50°C is commonly applied before charging to glass-lined reactors. Neutral pH dissolution of the sodium salt reduces free-acid slurry handling and improves compatibility with standard stainless-steel transfer lines compared with the free acid.
The sodium D-aspartate product differs from sodium L-aspartate and sodium DL-aspartate at the chiral center, which controls biological recognition, enzymatic oxidation, and crystallization behavior. The D-enantiomer is not proteinogenic and is not a direct substitute for L-aspartate in ribosomal peptide synthesis. In chiral pool synthesis, however, the D-configuration provides access to D-amino-acid-containing fragments that cannot be obtained from L-aspartate without inversion steps. The sodium counterion increases aqueous dissolution relative to free D-aspartic acid, which is only sparingly soluble in water.
| Attribute | Sodium D-aspartate | Sodium L-aspartate | Sodium DL-aspartate | D-aspartic acid free acid |
|---|---|---|---|---|
| Chirality | D-configuration | L-configuration | Racemic mixture | D-configuration |
| Anhydrous formula weight | 155.08 g/mol | 155.08 g/mol | 155.08 g/mol | 133.10 g/mol |
| Water solubility at 25°C | Freely soluble in water | Freely soluble in water | Freely soluble in water | Sparingly soluble; approximately 5 g/L |
| pH of 1% aqueous solution | 7.0–8.0 | 7.0–8.0 | 7.0–8.0 | 2.0–3.0 |
| Typical downstream role | Chiral building block, D-amino acid studies, analytical reference | Cell culture media, buffering, parenteral nutrition | Non-chiral control, racemic crystallization studies | Chiral pool for D-aspartate derivatives |
| Enzymatic recognition | Substrate for D-aspartate oxidase | Enters transamination and urea cycle pathways | Mixed recognition; not a clean biological control | Substrate for D-aspartate oxidase after neutralization |
Dry-powder handling of sodium D-aspartate differs from the free acid because the sodium salt is hygroscopic and can cake when particle surfaces adsorb moisture above the critical humidity. In gravimetric feeders with twin-screw configurations, bridging at hopper cone outlets has been observed when the anhydrous powder is exposed to ambient relative humidity of ≥55% for more than 4 h. The effect is more pronounced for anhydrous material milled to a D50 below 100 µm. Closed transfer to a double-cone blender under ≤40% RH is used to maintain flow. Powder-flow characterization by USP <1174> is recommended because particle-size distribution varies with crystallization and milling; poor flow is common when the Carr index exceeds 25. Addition of 0.5–1.0 wt% fumed silica or wet granulation with deionized water reduces segregation in direct-compression blends. Bulk density and tapped density should be confirmed on each lot because milling conditions affect both values and alter gravimetric feed calibration.
When sodium D-aspartate is dissolved in buffered media above pH 9.0, the α-carbon becomes susceptible to base-catalyzed enolization, and the D-configuration can invert to the L-enantiomer. This limits preparative chromatographic purification and spray-drying of alkaline solutions. For processes requiring high pH, temperature should be maintained below 40°C and residence time below 2 h when enantiomeric excess above 99.0% is required. At neutral pH, aqueous solutions of the monosodium salt are considered process-stable at 2–8°C for short hold times; however, published kinetic data for racemization in the exact buffer systems used in downstream conjugation are limited. Process development should verify enantiomeric excess by chiral HPLC after each hold time and before isolation. Strongly alkaline conditions also promote salt displacement and may alter the sodium-to-aspartate stoichiometry in prepared concentrates.
For cell culture and perfusion bioreactor applications, the D-enantiomer is handled as an experimental variable rather than as a nutrient substitute for L-aspartate. Chemically defined media formulated with sodium D-aspartate require confirmation of enantiomeric purity because L-aspartate present above 0.5% may contribute to growth in control arms intended to be D-aspartate-free. The material is incompatible with nitrosating agents under acidic conditions and should not be dry-blended with strong oxidizing agents. Aqueous solutions are not autoclaved; sterile filtration through a 0.22 µm polyethersulfone membrane is preferred. Long-term storage is specified at 2–8°C in sealed containers under desiccant, with retest intervals established by water content and chiral purity rather than by fixed calendar date alone.
