| HS Code | 513168 |
| Chemicalname | Sodium L-ascorbate |
| Molecularformula | C6H7NaO6 |
| Molecularweight | 198.11 g/mol |
| Casnumber | 134-03-2 |
| Appearance | White to off-white crystalline powder |
| Solubility | Freely soluble in water; sparingly soluble in ethanol; practically insoluble in chloroform and ether |
| Ph | 6.0 to 7.5 in 5% w/v aqueous solution |
| Assay | 99.0% to 101.0% calculated on the dried basis |
| Specificopticalrotation | +101.0° to +106.0° |
| Meltingpoint | 218°C with decomposition |
| Storagecondition | Store in a tightly closed container, protected from light, heat, and moisture |
| Dosageformcompatibility | Suitable for tablets, capsules, granules, oral and injectable formulations |
As an accredited Ascorbic Sodium Pharma Grade API for Tablet / Capsule / Granule / Injection, Oral & Injectable factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 25 kg sealed fiber drums with double polyethylene liners, labeled for pharma use, ideal for oral and injectable formulations. |
| Container Loading (20′ FCL) | 20′ FCL: palletized drums/cartons of Ascorbic Sodium Pharma Grade API, securely stowed, ventilated, dry, protected from contamination. |
| Shipping | Ship as pharmaceutical API in sealed, moisture-proof containers, preferably aluminium bags or HDPE drums. Store below 25°C, protected from light and humidity. Use temperature-controlled, non-food transport with clear GMP labeling. Ensure FDA/WHO-compliant documentation, chain-of-custody records, and tamper-evident seals for oral and injectable grade safety. |
| Storage | Store in a tightly closed, light-resistant container in a cool, dry place below 25°C. Protect from moisture and humidity, as the material is hygroscopic. Avoid exposure to direct sunlight and excessive heat. Ensure packaging remains sealed when not in use to maintain stability for oral and injectable pharmaceutical formulations. |
| Shelf Life | Shelf life: 24 months from manufacture date when stored in tightly sealed containers, protected from light, heat, and moisture. |
In direct compression lines operating at sustained batch output above 120,000 tablets/h, sodium ascorbate API is metered through loss-in-weight feeders into a 1500 L bin blender after pre-sieving through a 0.8 mm oscillating sieve. The formulation is anchored to Ph. Eur. 01/2024:0251 and USP Sodium Ascorbate, with assay acceptance of 99.0–101.0% on the dried basis and elemental impurity testing per ICH Q3D Option 1. For dosage uniformity, finished tablets are sampled under USP <905> and Ph. Eur. 2.9.40; acceptance value ≤ 15.0 is applied to batches containing 500 mg and 1000 mg label strengths. Direct compression demands fine particle size without excessive fines; sodium ascorbate D90 is typically controlled to 180–250 µm, with D10 ≥ 45 µm to limit segregation in tablet press hoppers. API loading range in the tablet core spans 55–85% w/w, diluted with microcrystalline cellulose 8–25% w/w, croscarmellose sodium 2–5% w/w, colloidal silicon dioxide 0.5–2% w/w, and magnesium stearate 0.5–1.5% w/w. Equipment-specific compression behavior is observed on a 27-station rotary press with turret speed 40–80 rpm: precompression force 5–10 kN and main compression force 12–22 kN produce tablet hardness 60–120 N without excessive die-wall adhesion. Sodium ascorbate has low compactability relative to microcrystalline cellulose; exceeding 25% w/w microcrystalline cellulose reduces capping at high turret speeds but may extend disintegration if tablet hardness exceeds 120 N. Batch-to-batch variance in API moisture above 0.5% w/w causes feeding inconsistency in the press hopper and increases die-wall residue, which is managed by spraying the press feed frame with dry nitrogen when relative humidity exceeds 50% RH. Terminal products include film-coated vitamin C tablets with label claims of 500 mg and 1000 mg, coated with hydroxypropyl methylcellulose/polyethylene glycol films to reduce moisture uptake and mask the slightly saline taste of sodium ascorbate.
The limiting variable in capsule filling is not bulk density but equilibrium moisture content after roller compaction. Sodium ascorbate is hygroscopic; when API moisture exceeds 0.8% w/w, dry granulate exhibits punch filming during ribbon compaction and tamping pin buildup on capsule machines. Roller compaction is therefore specified with an inlet air dew point ≤ -20 °C and processing room relative humidity ≤ 30% RH. The granulation formula comprises 60–80% w/w sodium ascorbate, 10–25% w/w pregelatinized starch, 3–7% w/w crospovidone, 1–3% w/w sodium stearyl fumarate, and 0.3–1.2% w/w colloidal silicon dioxide. Ribbon compaction is operated at hydraulic pressure 40–80 bar, roll speed 4–12 rpm, and gap width 1.5–3.0 mm, followed by screen milling through 0.8–1.25 mm mesh to produce granule D50 250–500 µm. The resultant granulate is filled into hard hydroxypropyl methylcellulose capsules on dosator-type fillers with fill weight target 450–650 mg and fill weight relative standard deviation ≤ 2.0%. Dissolution testing follows USP <711> Apparatus 2 at 50 rpm in 0.1 N HCl, with Q = 80% released at 45 min. Finished capsules comply with Ph. Eur. 2.9.1 disintegration and USP <2021> microbial enumeration for nonsterile oral products. The production-scale failure mode is granulate overwetting during room-temperature shifts: a rise from 22 °C to 26 °C at 60% RH can increase particle moisture by 0.5% w/w within 30 min, causing the rotating capsule brush to blind with granulate fines. Terminal products are HPMC capsules containing 250 mg and 500 mg sodium ascorbate, packaged in PVC/PVDC-aluminum blisters with desiccant pouches to maintain internal relative humidity below 30% RH over a 24-month shelf life.
Unit-dose sachet filling of orally dissolving sodium ascorbate granules imposes a narrower process window than rotary tablet compression because the powder blend must simultaneously retain flow through a vertical form-fill-seal hopper and reconstitute in water within 120 s without residue. The formulation is built around 80–95% w/w sodium ascorbate, 2–8% w/w anhydrous citric acid, 1–5% w/w sodium citrate dihydrate, 0.15–0.6% w/w sucralose, and a binder such as maltodextrin 1–5% w/w; if a noncariogenic bulk sweetener is required, sorbitol can replace up to 10% w/w of maltodextrin. Blending is performed in a bin blender at 60–70% vessel loading for 10–20 min at 6–12 rpm, after sodium ascorbate has been milled to a D90 ≤ 200 µm to avoid stratification. Granulation may be avoided when the sachet powder is intended for solution, but if granulation is required to reduce dusting, wet granulation with anhydrous ethanol is used at 5–9% w/w granulating liquid, with bowl chopper speed 300–600 rpm and impeller speed 150–300 rpm. Drying follows in a fluid-bed dryer with inlet air temperature 35–50 °C, product temperature 25–32 °C, and endpoint moisture ≤ 0.5% w/w. Fill weight for a 1 g sachet is controlled to a relative standard deviation ≤ 1.5% on auger fillers equipped with a 0.3 mm mesh powder filter. Packaging uses paper/aluminum foil/polyethylene laminate with oxygen transmission rate ≤ 0.1 cm³/(m²·day·bar); strip-pack barrier must withstand heat-seal peel strength ≥ 6 N/15 mm per ASTM F88/F88M-15. The finished sachet product is tested for uniformity of mass under Ph. Eur. 2.9.5 and for pH of the reconstituted solution under Ph. Eur. 2.2.3, with a pH range 6.5–7.5 for sodium ascorbate-based products. Terminal products include single-dose oral powder sachets containing 500 mg, 1000 mg, and 2000 mg sodium ascorbate, presented in tear-open aluminum laminates and intended for reconstitution in 50–200 mL potable water.
| Operating parameter | Direct compression tablet | Roller-compacted capsule | Effervescent tablet | Oral sachet |
|---|---|---|---|---|
| API loading nominal proportion | 55–85% w/w | 60–80% w/w | 20–40% w/w | 80–95% w/w |
| Loss on drying after granulation | ≤0.5% w/w | ≤0.8% w/w | ≤0.2% w/w | ≤0.5% w/w |
| Particle size control | D90 180–250 µm | D50 250–500 µm | D90 250–400 µm | D90 ≤200 µm |
| Compression force | 12–22 kN | n/a–capsule fill | 5–15 kN | n/a–sachet fill |
| Disintegration or reconstitution criterion | Ph. Eur. 2.9.1 ≤30 min | USP <711> Q=80% at 45 min | Ph. Eur. 2.9.1 ≤5 min | ≤120 s reconstitution |
Oxygen exclusion is the controlling parameter in heat-sterilized sodium ascorbate injection, because the C-2 hydroxyl group undergoes oxidative degradation to dehydroascorbic acid and subsequent irreversible hydrolysis. Injection-grade sodium ascorbate is dissolved in Water for Injections to a concentration of 100–500 mg/mL in a closed stainless steel vessel with nitrogen overlay at 0.2–0.5 bar positive pressure. The solution is adjusted to pH 5.5–7.0 with sodium hydroxide or hydrochloric acid; addition of disodium edetate at 0.01–0.1% w/v chelates trace copper and iron emitted from vessel passivation layers. Sodium metabisulfite may be added at 0.05–0.3% w/v as an oxygen scavenger, but for high-purity API intended for sensitive populations the elimination of sulfite is preferred and the formulation is instead sparged with pharmaceutical nitrogen for at least 30 min. Sterilization is validated per Ph. Eur. 5.1.1 and USP <1229.1>; if terminal steam sterilization at 121 °C for 15 min produces assay loss > 2.0% or discoloration above AY3 under Ph. Eur. 2.2.2, the line is converted to aseptic filtration through a 0.22 µm PVDF filter into Type I borosilicate glass vials. Filled vials are flushed with nitrogen before stoppering to maintain headspace oxygen ≤ 2.0% v/v. Finished vials must meet USP <1>, USP <71> sterility, USP <85> bacterial endotoxin limit ≤ 0.5 EU/mg, and USP <788> particulate matter limits of ≤ 6000 particles per container ≥ 10 µm and ≤ 600 particles per container ≥ 25 µm. Manufacturing is executed under 21 CFR 211 aseptic processing requirements when terminal sterilization is not feasible. Products include 50 mL vials containing 500 mg/mL sodium ascorbate injection, 100 mL pharmacy bulk packages, and 10 mL ampoules for multi-dose clinical use.
Freeze-drying of sodium ascorbate solutions above 100 mg/mL introduces a crystallization lag during shelf cooling that influences primary drying design; the API may remain amorphous in the frozen matrix unless annealing is inserted. The formulation for lyophilized parenteral sodium ascorbate contains 20–150 mg/mL sodium ascorbate in the bulk solution, mannitol or trehalose 2–5% w/v as bulking agent and glass-forming excipient, and Water for Injections q.s.; pH is adjusted to 5.5–7.0 before sterile filtration. Thermal analysis by differential scanning calorimetry typically shows a eutectic melting event between -25 °C and -15 °C, but published data for this specific multicomponent system are limited; cycle design therefore uses conservative thermal margins based on product thermocouple data rather than literature collapse temperatures. The cycle proceeds from shelf pre-cooling to -45 °C at 0.5–1.0 °C/min, with an annealing step at -20 °C for 2–4 h to crystallize mannitol and prevent vial breakage. Primary drying is operated at shelf temperature -25 °C to -10 °C and chamber pressure 50–150 mTorr for 24–48 h; secondary drying at shelf temperature 25–35 °C for 6–12 h reduces cake moisture to ≤ 1.0% w/w by USP <921> Karl Fischer titration. The product is stoppered under vacuum or low-oxygen nitrogen and tested for sterility under Ph. Eur. 2.6.1, bacterial endotoxins under Ph. Eur. 2.6.14, and subvisible particulates under Ph. Eur. 2.9.19. The primary production-scale defect is cake collapse at the vial base when primary drying is initiated above the glass transition temperature of the amorphous sodium ascorbate phase; this is detected by cake height mapping and sublimation front temperature probes. Terminal products include lyophilized powder for injection in 500 mg and 1000 mg vials, reconstituted with 5 mL or 10 mL Water for Injections to yield a clear, pale yellow solution.
| Quality attribute | Standard designation | Injectable solution acceptance | Lyophilized product acceptance |
|---|---|---|---|
| Sterility | USP <71>, Ph. Eur. 2.6.1 | No growth | No growth |
| Bacterial endotoxins | USP <85>, Ph. Eur. 2.6.14 | ≤0.5 EU/mg | ≤0.5 EU/mg |
| Particulate matter | USP <788>, Ph. Eur. 2.9.19 | ≤6000 particles/container at ≥10 µm; ≤600 particles/container at ≥25 µm | Same after reconstitution |
| Moisture | USP <921> | n/a | ≤1.0% w/w |
| pH | Ph. Eur. 2.2.3 | 5.5–7.0 | 5.5–7.0 after reconstitution |
| Assay | USP Sodium Ascorbate | 95.0–105.0% of label claim | 95.0–105.0% of label claim |
When the formula contains 20–40% w/w sodium ascorbate, 18–30% w/w anhydrous citric acid, 22–35% w/w sodium bicarbonate, and 5–10% w/w sorbitol or polyethylene glycol 6000, residual moisture is the primary critical quality attribute during compression. The granulation is prepared with anhydrous ethanol or isopropanol in a high-shear granulator; the granulating liquid is added at 5–10% w/w to initiate the citric acid–sodium bicarbonate reaction only at a controlled low rate, then the mass is dried to loss on drying ≤ 0.2% w/w under vacuum at 40–50 °C. Compression is performed in rooms held at ≤ 20% RH and 18–22 °C, with tablet presses fitted with moisture-sealed punches and low-dust extraction. Compression force is controlled to 5–15 kN to produce tablet hardness 40–90 N, because higher compact hardness can prolong disintegration beyond the compendial limit. Disintegration follows Ph. Eur. 2.9.1 for effervescent tablets in 200 mL water at 15–25 °C; the acceptance time is ≤ 5 min. Finished products are packaged in polypropylene tubes with silica gel or molecular sieve stoppers, and desiccant capacity is sized for headspace moisture ingress ≤ 0.5 mg/day per tube at 40 °C/75% RH. Compliance for the finished tablet includes assay by USP Sodium Ascorbate, uniformity of dosage units by Ph. Eur. 2.9.40, organic acid profile by HPLC with UV detection at 245 nm, and residual solvent testing under USP <467> for ethanol and isopropanol. Sodium bicarbonate content is measured by acid-base titration with 0.1 N hydrochloric acid. Terminal products are effervescent oral tablets containing 1000 mg and 500 mg sodium ascorbate, yielding a clear orange- or lemon-flavored solution with a pH of 5.8–6.6 after effervescence.
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The substance designated Ascorbic Sodium Pharma Grade API is sodium L-ascorbate, identified by CAS registry number 134-03-2, molecular formula C6H7NaO6, and relative molecular mass 198.11 g/mol. The product is not assigned a proprietary model number; it is ordered by the pharmacopoeial name Sodium Ascorbate, the declared grade, and the intended route of administration. The material is a white to faintly yellow crystalline powder intended for further processing into tablet, capsule, granule, oral powder, oral solution, and injectable finished products. It meets the current monograph requirements of USP-NF, Ph.Eur., and BP where applicable. Release assay is not less than 99.0% and not more than 101.0% on the dried basis. A 10% w/v aqueous solution has pH 7.0–8.0. Each gram of sodium ascorbate supplies 0.889 g of ascorbic acid equivalent and 11.6% w/w sodium. This distinguishes the product from ascorbic acid, which is acidic in solution and supplies no sodium. The neutral salt form reduces the acid-related gastric irritation seen with high-dose ascorbic acid tablets and permits direct pH adjustment in injectable vitamin C formulations without excessive buffering capacity.
| Attribute | Oral tablet/capsule grade | Injectable grade | Test method |
|---|---|---|---|
| Appearance | White to faintly yellow crystalline powder | White crystalline powder; solution clear after dissolution | Ph.Eur. 2.2.1 |
| Assay, dried basis | 99.0–101.0% | 99.0–101.0% | HPLC or iodometric titration per USP-NF Sodium Ascorbate monograph |
| pH (10% w/v aqueous solution) | 7.0–8.0 | 7.0–8.0 | Ph.Eur. 2.2.3 / USP <791> |
| Water content | ≤ 0.25% | ≤ 0.25% | Karl Fischer, USP <921> |
| Elemental impurities | ICH Q3D oral limits | ICH Q3D parenteral limits | USP <232> / USP <233> |
| Bacterial endotoxins | Not specified | Derived from dose; often ≤ 0.25 EU/mg | USP <85> / Ph.Eur. 2.6.14 |
| Particulate matter | Not specified | Meets USP <788> after dissolution | USP <788> |
Buffered oral powders and effervescent granules require a source of ascorbate that does not lower the solution pH below the range tolerated by the final product. Ascorbic acid has a 5% w/v solution pH below 3.0; sodium ascorbate in 10% w/v solution is neutral at pH 7.0–8.0. In injectable formulations, the neutral pH reduces pain on injection and minimizes incompatibility with pH-sensitive actives. The sodium content is not negligible: a 1 g dose of sodium ascorbate contributes approximately 116 mg of sodium, which must be counted in sodium-restricted cardiovascular or renal dosage regimens. Calcium ascorbate is an alternative where sodium intake is restricted, but its aqueous solubility is lower and the calcium cation can precipitate with phosphate buffers. Sodium erythorbate is stereochemically distinct and does not substitute for sodium ascorbate in pharmacopoeial vitamin C therapy.
Wet granulation of sodium ascorbate is feasible but requires control of moisture and drying temperature. In high-shear granulators, the API partially dissolves in the binder solution, increasing granulating fluid viscosity and producing hard granules if the liquid-to-solid ratio is excessive. On production lines, the wet mass is best discharged promptly and transferred to a fluid-bed dryer with inlet air temperature not exceeding 60 °C and product temperature maintained below 45 °C. Residual granule moisture should be checked by loss-on-drying before lubrication. The dried granules are milled through a 0.8–1.2 mm screen. Fines below 150 μm may be reworked but should not exceed 20% of the final granule fraction because segregation can alter content uniformity in high-dose tablets. Direct compression is generally limited to low-dose or pre-granulated material because the raw powder is hygroscopic and prone to caking. Roller compaction can produce a free-flowing intermediate under low-humidity conditions; the compact is milled and blended with extragranular disintegrant and lubricant to control flow and disintegration. Lubrication with magnesium stearate at 0.5–1.0% w/w reduces ejection force but can lower tablet tensile strength. Sodium stearyl fumarate at 1.0–2.0% w/w is used when extended mixing is required. Crospovidone or croscarmellose sodium at 2.0–5.0% w/w is typically necessary for rapid disintegration of high-dose tablets containing over 500 mg of sodium ascorbate.
In capsule filling, granulated material performs better than raw API. Colloidal silicon dioxide at 0.2–0.5% w/w and a glidant such as talc reduce electrostatic sticking to the dosator or tamping pins. Blends with sodium ascorbate above 500 mg per capsule often require densification by dry granulation because low bulk density can exceed the available fill volume. Dissolution testing follows USP <711> apparatus 2 with 900 mL of water or 0.1 N hydrochloric acid at 37 °C for immediate-release products; specific acceptance criteria are product-specific and are established during development. Content uniformity is assessed by USP <905> or Ph.Eur. 2.9.40. For high-dose tablets, assay variability is controlled by granule particle-size distribution. A starting API with water content above 0.25% can agglomerate prematurely during the dry mixing phase; pre-sieving through a 710 μm screen reduces this risk. Granule water activity after drying should be maintained below 0.5 to limit hydrolysis and browning.
Injectable-grade sodium ascorbate is not supplied as a sterile API. The powder must be dissolved in Water for Injection and filtered through a validated sterilizing-grade membrane, or the filled solution must be terminally sterilized if container and solution stability permit. Because the sodium salt is freely soluble in water, concentrated aqueous solutions are feasible, but the solution is sensitive to dissolved oxygen and trace metal catalysis. The oral and injectable grades differ mainly in bacterial endotoxin, particulate matter, and elemental impurity controls. The material used for injection should be evaluated using the finished-product limits in USP <85> and Ph.Eur. 2.6.14; the API limit must be derived from the maximum intended dose and the final reconstitution volume. A common API endotoxin acceptance limit of 0.25 EU/mg is often applied for high-volume parenterals, but it is not a universal requirement.
Dissolved oxygen is the dominant degradation driver in aqueous sodium ascorbate injection. The oxidation sequence forms dehydroascorbic acid and then 2,3-diketogulonic acid; both intermediates lack vitamin C activity and can contribute to yellow discoloration. Nitrogen sparging to dissolved oxygen below 1 ppm and a headspace oxygen limit of 2% v/v are standard controls. Trace copper and iron ions accelerate the reaction; edetate disodium at 0.01–0.1% w/v or citric acid is added as a chelator. pH is maintained between 6.5 and 7.5 with sodium bicarbonate or sodium hydroxide. The solution must be protected from light; amber glass or opaque polyolefin containers are appropriate for light-sensitive parenterals. Particulate matter after dissolution should meet USP <788> or Ph.Eur. 2.9.19. The API powder should be free from visible foreign matter, and its subvisible particle burden after dissolution must be low enough not to cause the finished batch to fail the compendial limit for the chosen container volume. Incompatibilities include strong oxidizing agents, silver nitrate, mercuric chloride, and iodine; these react with the enediol group. Solutions should not be stored with headspace oxygen and should be used within the stability period validated for the specific container-closure system.
For injectable grade, elemental impurities are controlled according to ICH Q3D Option 1 for the parenteral route. Residual solvents are controlled under ICH Q3C. Manufacturing equipment should be passivated stainless steel to minimize iron leaching. Filtration through 0.22 μm sterilizing-grade polyethersulfone or PVDF membrane is used after bulk solution preparation. Filter compatibility must be confirmed because the solution can affect membrane flux. Published data for specific container-closure configurations is limited; therefore, formulation-specific stability studies are required under ICH Q1A(R2).
Solid sodium ascorbate is stable in dry air but darkens on prolonged exposure to light and moisture. Storage at 15–25 °C in a dry place is typical; relative humidity above 60% RH causes caking and surface yellowing, and water uptake accelerates oxidation. The API is packed in double polyethylene bags inside fiber drums or in opaque HDPE containers; nitrogen overlay is used where extended retest periods are required. Light-resistant containers are specified because the compound is light-sensitive. Under ICH Q1A(R2) long-term conditions, the assigned retest period is based on assay, water content, pH, and appearance. Suppliers commonly assign a 24-month retest period for oral grade and a shorter interval for injectable grade, but published data for specific packaging configurations is limited beyond supplier stability protocols. Do not combine with reducing sugars in dry granulations without compatibility assessment; Maillard-type interactions can lower assay and produce brown discoloration. Avoid copper, iron, and other transition metal equipment surfaces.
Formulation with ammonium salts or strong alkali should be avoided because the ascorbate ion is susceptible to base-catalyzed oxidation. Stability of oral granules is improved by reducing moisture to below 0.5% w/w and by adding an internal desiccant in the package. The enediol group also interacts with iodine and other oxidizing agents; therefore cleaning validation of shared equipment must consider redox residues. The product is not classified as a hazardous oxidizing substance, but it is a reducing agent and should be segregated from strong oxidizers in storage.
For formulators comparing vitamin C sources, the choice between ascorbic acid and sodium ascorbate is primarily based on pH, sodium load, and compatibility with the finished dosage form. Ascorbic acid is preferred in acidic chewable tablets and dry vitamin C powders where sourness is acceptable. Sodium ascorbate is preferred in buffered tablets, effervescent granules, injectable solutions, and combination products where acid-labile actives are present. Calcium ascorbate avoids sodium but contributes calcium and has lower aqueous solubility; it is used in mineral combinations and soft-chew products. Ascorbyl palmitate is not a direct substitute for aqueous oral or injectable applications because it is lipophilic and intended for fat-based formulations. Sodium erythorbate is not a pharmacopoeial vitamin C active and must not be labeled as providing ascorbic acid activity. The sodium content of sodium ascorbate is a critical specification input for unit-dose calculation: a 1000 mg tablet containing 1000 mg sodium ascorbate contributes approximately 116 mg of sodium, which may exceed 100 mg per unit sodium labelling thresholds in some regulatory frameworks.
