| HS Code | 572548 |
| Chemical Name | L-Lysine |
| Cas Number | 56-87-1 |
| Molecular Formula | C6H14N2O2 |
| Molecular Weight | 146.19 g/mol |
| Appearance | White to off-white crystalline powder |
| Solubility | Freely soluble in water; sparingly soluble in ethanol |
| Melting Point | 215 °C (decomposes) |
| Density | 1.125 g/cm³ (approx.) |
| Pka Values | 2.15 (α-COOH), 9.16 (α-NH3+), 10.67 (ε-NH3+) |
| Storage Conditions | Store in a cool, dry, well-ventilated area; protect from light and moisture |
As an accredited L-lysine Base factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | L-lysine Base is supplied in sealed 25 kg fiber drums with polyethylene liner, ensuring purity and stability. |
| Container Loading (20′ FCL) | L-lysine Base loaded in 20′ FCL using palletized bags, securely stowed, weight-balanced, and protected from moisture for safe transport. |
| Shipping | L-lysine Base ships as a dry powder in sealed, moisture-proof packaging to prevent clumping and degradation. Store at room temperature in a cool, dry area away from strong oxidizers. No special dangerous goods designation is required for standard ground or air freight when properly labeled and documented. |
| Storage | Store L-lysine Base in a cool, dry, well-ventilated area, away from moisture, direct sunlight, and incompatible materials such as strong oxidizing agents or acids. Keep the container tightly sealed when not in use to prevent clumping or degradation. Ensure proper labeling and avoid dust generation; use appropriate personal protective equipment when handling. |
| Shelf Life | L-lysine Base is stable for 2–3 years when stored cool, dry, and tightly sealed. |
In monogastric feed formulation, L-lysine base is handled as a crystalline amino acid source with an active lysine equivalence of 98.5% for feed-grade material, requiring a shift from L-lysine monohydrochloride calculations. L-Lysine monohydrochloride contains 80.0% L-lysine on a stoichiometric basis, so 1.000 kg of 98.5% L-lysine HCl supplies 788 g active lysine, while the same nominal purity L-lysine base supplies 985 g active lysine. Formulators apply an equivalence factor of 0.80 when replacing the hydrochloride with free base on a weight-for-weight basis. In 7–11 kg post-weaning piglet rations, NRC 2012 lists a standardized ileal digestible lysine requirement of 12.5 g/kg diet. A basal corn–soy matrix typically provides 9.0–10.5 g/kg digestible lysine, leaving 2.0–3.5 g/kg to be supplied as crystalline lysine. Addition of 2.5 g/kg net lysine to a 1,000 kg mixer batch requires 2.54 kg of 98.5% L-lysine base, whereas the equivalent L-lysine HCl requirement is 3.17 kg. This difference alters dense-phase pneumatic conveying behaviour and loss-in-weight feeder calibration. Published feed-grade technical datasheets report bulk densities between 0.55 g/cm³ and 0.70 g/cm³ for L-lysine base, which is lower than settled crystalline L-lysine HCl values. At relative humidity above 60%, the free base cakes on filter socks and rotary valve clearances; ground-level hoppers with desiccant breathers are specified. In a double-shaft paddle mixer, a coefficient of variation below 5% is obtainable with 3–5 min mixing after 1:10 premix dilution into ground corn carrier. EU feed additive classification is governed by EC Regulation 1831/2003 Annex I. US use is covered by 21 CFR 582.5161. Total and free lysine content is verified by amino acid analysis following acid hydrolysis with ISO 13903:2005.
Steam pelleting exposes crystalline L-lysine base to a conditioning barrel with steam injection at 70–85°C and residence time of 30–90 s. Under these conditions, the free base remains largely intact because thermal decomposition of crystalline L-lysine begins only at temperatures above 224°C. The recovery risk is not the crystalline lysine fraction but the ε-amino group participating in Maillard condensation when heat and moisture mobilise reducing sugars from cereal fines, whey permeate, or damaged starch. At conditioning temperatures above 80°C with added lactose or molasses, reactive lysine can decline within 60 s; published data for this specific configuration is limited, so process trials are required for each ration. Extrusion of complete feeds in a twin-screw extruder with L/D 40:1 at barrel temperatures above 120°C and moisture content 18–22% creates a more severe Millard-prone environment than pelleting. Split addition of L-lysine base after the die head, or in vacuum coating, is used when extrusion temperature exceeds 110°C. Reactive lysine is determined by fluoro-dinitrobenzene derivatisation or OPA-HPLC after acid hydrolysis according to ISO 13903:2005. Pellet durability is not significantly affected at lysine base inclusion rates below 10 g/kg, but higher concentrations may raise fines because the crystalline amino acid contributes no binding capacity.
In high-density CHO fed-batch processes, L-lysine base is used in concentrated alkaline feeds to avoid chloride accumulation from L-lysine hydrochloride. Basal media such as DMEM and RPMI 1640 conventionally list L-lysine hydrochloride, not free base. Stoichiometric replacement requires multiplication by the molecular weight ratio 146.19/182.65, equivalent to 0.80. The table below gives the two most commonly cited basal medium conversions.
| Basal medium | L-Lysine HCl concentration | L-lysine base equivalent | Chloride removed |
|---|---|---|---|
| DMEM high glucose | 146 mg/L | 116.8 mg/L | 28.3 mg/L |
| RPMI 1640 | 40 mg/L | 32.0 mg/L | 7.8 mg/L |
L-lysine base is freely soluble in water, allowing 100 g/L or higher stock solutions at 25°C for 10× fed-batch concentrates. In such alkaline feeds, pH is adjusted to 10.5–11.0 with sodium hydroxide after base addition. Autoclaving at 121°C for 15 min in the presence of glucose is avoided because the ε-amino group forms furosine and other Maillard adducts with reducing sugars. Sterile filtration through 0.22 μm PVDF or PES membranes is specified for L-lysine base-containing feeds. Chloride reduction is meaningful in late-stage perfusion cultures where chloride concentration above 110–120 mmol/L is associated with reduced specific productivity in some recombinant CHO lineages. The free base form is not used in unbuffered basal media where pH shift would exceed bicarbonate buffer capacity.
L-lysine acetylsalicylate is synthesised from L-lysine base and acetylsalicylic acid in a 1:1 molar ratio. The free base is preferred over the hydrochloride because inorganic chloride would remain as counterion after salt formation and complicate crystallisation. Anhydrous L-lysine base has a molecular weight of 146.19 g/mol and acetylsalicylic acid 180.16 g/mol. The ε-amino group pKa of 10.5 permits deprotonation of the acetylsalicylic acid carboxyl group without addition of inorganic hydroxide. In a glass-lined reactor, L-lysine base is dissolved in 70% ethanol at 10–15°C, and acetylsalicylic acid is added incrementally to maintain reaction pH 5.0–6.0. Above pH 7.0, acetylsalicylate hydrolysis to salicylate accelerates; below pH 4.5, precipitation of free acid occurs. The wet crystal mass is dried under vacuum at jacket temperature not exceeding 35°C. Residual water is controlled because water activity directly influences acetylsalicylate hydrolysis. Karl Fischer titration is performed according to Ph. Eur. 2.5.12, and free salicylic acid is monitored by HPLC against a monograph limit. Residual ethanol is determined by gas chromatography per Ph. Eur. 2.4.24. L-lysine base used for pharmacopoeial salt synthesis must meet USP-NF L-Lysine monograph identity, assay, and residual impurity criteria.
Whole-cell biotransformation of L-lysine base to cadaverine operates as a downstream monomer route for partially bio-based polyamides. The reaction is catalysed by lysine decarboxylase in recombinant Corynebacterium glutamicum or Escherichia coli. Using L-lysine base rather than hydrochloride removes the HCl neutralisation step and reduces chloride ion concentration in the biocatalyst broth. In a fed-batch stirred-tank reactor, L-lysine base is fed to maintain substrate concentration at 0.5–1.0 mol/L while pH is held at 6.0–6.5 through the amine product itself, reducing external acid demand compared with hydrochloride feed. Molar conversion to cadaverine is reported above 99% in optimised whole-cell systems at pilot scale. The broth is clarified, and cadaverine is recovered by cation exchange or two-phase extraction, then purified by vacuum distillation. Cadaverine is copolymerised with sebacic acid to produce polyamide 5,10, a semi-bio-based engineering polymer with a melting point above 200°C. Melt processing of PA 5,10 is carried out on twin-screw extruders with L/D 40:1 at barrel temperatures 230–250°C. Mechanical property evaluation follows ISO 527-1:2019 for tensile testing and ISO 178:2019 for flexural testing. Chloride-free feedstock is critical because residual chloride in the recovered monomer can corrode injection-moulding screws and degrade polymer colour.
Dietary supplement tablet compression converts L-lysine base into solid-dose products declared as “L-Lysine” on the Supplement Facts panel. The free base is more hygroscopic than the hydrochloride salt, so the compression suite is maintained below 40% relative humidity. Direct compression is generally avoided because L-lysine base exhibits poor compactibility and sticking at high humidity. Dry granulation by roller compaction with a 20-mesh screen is the preferred agglomeration step. Typical tablet formulations contain 500 mg or 1000 mg L-lysine base per tablet, with microcrystalline cellulose and magnesium stearate as excipients. The blend is compressed on rotary tablet presses with compression force 10–20 kN. Finished product release includes weight variation per USP 2091, disintegration per USP 2040, and amino acid assay by HPLC against USP-NF L-Lysine monograph. Compliance with 21 CFR 111 current good manufacturing practice is mandatory. The free base should not be combined with high-dose reducing sugars in effervescent or chewable matrices without moisture-barrier coating because the ε-amino group is reactive under acidic storage conditions.
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L-lysine base, CAS 56-87-1, is the free amino acid form of L-lysine with molecular formula C6H14N2O2 and molecular weight 146.19 g/mol. Commercial designations include L-Lysine Base 98.5% Feed Grade, L-Lysine Base 99.0% Food Grade, and L-Lysine Base Parenteral Grade; supplier SKUs rather than a single global model-number schema are used to encode grade, purity, mesh size, and packaging. The product is manufactured by fermentation with Corynebacterium glutamicum, followed by cation-exchange chromatography, ammonia elution, decolorization, vacuum evaporation, crystallization, and drying. Because the free base contains 100.0% L-lysine on an anhydrous basis, it supplies more amino acid per unit mass than the monohydrochloride salt, which provides approximately 80.0% L-lysine base equivalent and adds approximately 20.0% chloride by mass.
Typical release documents for food and pharmaceutical grades cite assay 98.5%–101.0% on the dried basis, specific rotation +25.5° to +27.5° at 25°C using a 6 N hydrochloric acid solution, pH 9.0–11.0 for a 5% aqueous solution, loss on drying ≤0.5%, residue on ignition ≤0.1%, chloride ≤0.05%, sulfate ≤0.03%, iron ≤10 mg/kg, heavy metals ≤10 mg/kg, arsenic ≤1 mg/kg, and D-lysine ≤1.0%. Pharmacopoeial monographs for related lysine salts, including USP 43-NF 38 L-lysine hydrochloride and Ph. Eur. 10.0 lysine hydrochloride, provide the identity, assay, chloride, sulfate, and iron controls that are frequently adapted for free-base material. The Food Chemicals Codex FCC 13 recognizes L-lysine monohydrochloride with assay 98.5%–101.0%; free-base product supplied for food use is tested against the same assay and impurity profile. Identity is confirmed by infrared absorption against a reference standard, and assay is performed by HPLC with pre-column derivatization or by non-aqueous titration.
| Parameter | Unit | Typical limit/range |
|---|---|---|
| Assay on dried basis | % | 98.5–101.0 |
| Specific rotation | ° | +25.5 to +27.5 |
| pH of 5% solution | — | 9.0–11.0 |
| Loss on drying | % | ≤0.5 |
| Residue on ignition | % | ≤0.1 |
| Chloride | % | ≤0.05 |
| Sulfate | % | ≤0.03 |
| Iron | mg/kg | ≤10 |
| Heavy metals | mg/kg | ≤10 |
| Arsenic | mg/kg | ≤1 |
| D-lysine | % | ≤1.0 |
Free-base lysine is usually isolated by eluting the cation-exchange resin with aqueous ammonia rather than with hydrochloric acid. This route yields the deprotonated α-amino group and produces a crystalline product that is hygroscopic and reactive toward atmospheric carbon dioxide. In storage trials with 20 kg polyethylene-lined fiber drums and ambient relative humidity above 65%, free-base lysine develops surface bicarbonate-carbonate under nitrogen-lean conditions, causing particle agglomeration and reduced screw-fed flowability. The bicarbonate layer can be detected by attenuated total reflectance infrared spectroscopy as a carbonate band near 1400 cm-1; if the product is not protected, dry powder dispensing equipment on a packaging line can lose feed-rate uniformity under high humidity, although published data for this specific configuration is limited. The preferred packaging is a nitrogen-flushed, heat-sealed liner inside a fiber drum, and high-humidity warehouses should maintain controlled air below 60% relative humidity.
For dry-blending operations, a horizontal ribbon mixer with a working volume of 500 L and an ingredient addition hopper fitted with a rotary airlock is used. Free-base lysine is added during the final 90 s of mixing to minimize shear heating. When the ambient dew point exceeds 15°C, the addition of 0.5% w/w hydrophobic fumed silica or 1.0% w/w tricalcium phosphate is required to maintain flow through a 25 mm screw conveyor. These conditioner levels are typical in tropical feed-milling operations; batch-to-batch variation in bulk density should be confirmed with a tapped density test before the conditioner is omitted.
L-lysine base is selected over L-lysine hydrochloride when chloride intake must be minimized or when the free amino acid is used to raise pH. In a direct substitution at equal amino acid concentration, 1.00 g of L-lysine base supplies 1.00 g of lysine equivalent, while 1.00 g of L-lysine hydrochloride supplies 0.800 g of lysine equivalent and introduces approximately 0.20 g of chloride. In chloride-sensitive Chinese hamster ovary cell culture, free-base lysine is used to maintain chloride below 10 mM in chemically defined feeds. The pH difference is pronounced: a 5% aqueous solution of the free base measures 9.0–11.0, whereas L-lysine hydrochloride solution measures 5.0–6.0. Free-base lysine therefore contributes alkalinity and may reduce the amount of sodium hydroxide required in feed pH control; the hydrochloride contributes an acidic counterion and is less hygroscopic.
| Form | CAS | Molecular weight | Lysine base equivalent | Typical pH in aqueous dilution | Primary use profile |
|---|---|---|---|---|---|
| L-lysine base | 56-87-1 | 146.19 g/mol | 100.0% on anhydrous basis | 9.0–11.0 | Chloride-sensitive cell culture, alkaline formulations |
| L-lysine hydrochloride | 657-27-2 | 182.65 g/mol | 80.0% | 5.0–6.0 | Standard dry premixes, pharmaceutical capsules |
| L-lysine sulfate feed grade | fermentation product; no single CAS | variable | 51–55% free-base equivalent | 4.0–5.0 | Cost-sensitive monogastric feeds |
In poultry and swine nutrition, L-lysine base is added to corn-soybean meal rations to correct lysine deficiency. Liquid free-base lysine is typically applied post-pellet through a volumetric metering system calibrated to deliver 0.1–0.5% of final feed mass. This placement avoids the high-temperature exposure of the pellet conditioner, where dry free lysine in the presence of reducing sugars from molasses or distiller’s dried grains can undergo Maillard reaction. Lysine recovery in feed is quantified by AOAC 994.12 or equivalent ion-exchange chromatography. Published data for this specific configuration is limited; therefore, dry free-base lysine is generally reserved for low-molasses formulations and mixing temperatures below 60°C in horizontal ribbon mixers.
Microbial fermentation media for enzyme production and recombinant protein expression are often formulated with free-base lysine to avoid the chloride or acetate load associated with other salts. In a mineral medium with glucose feed, replacing lysine acetate with L-lysine base at 2.0 g/L reduces sodium demand for pH control by approximately 0.8 meq/L per batch volume. The free base is added as a separate sterile stock solution after autoclaving because the elevated pH can precipitate phosphate salts if combined in a 10× feed concentrate. On a 200 L stirred-tank fermenter, the addition rate is typically controlled by a pH feed pump to maintain pH 6.8–7.2; addition above 10 g/L can increase osmolality beyond 400 mOsm/kg and reduce specific productivity in some Escherichia coli processes. Published data for this specific configuration is limited.
In chemically defined mammalian cell culture, free-base lysine can replace L-lysine acetate to reduce acetate accumulation in large-scale perfusion processes. L-lysine acetate contains approximately 70.9% free lysine equivalent and contributes acetate that may be metabolized, but high residual acetate above 20 mM can alter glycosylation in certain recombinant protein processes. Free-base lysine is therefore preferred in perfusion media where chloride and acetate are controlled independently; however, solubility limits and pH interaction with cystine and tyrosine in feed concentrates require that lysine be added as a separate pH-adjusted solution. Published data for this specific configuration is limited.
In oral nutritional products and amino acid premixes, free-base lysine is selected when the sodium, chloride, and organic counterion budgets are fixed. Compounding pharmacies use the free base to prepare low-chloride oral amino acid solutions; the pH of the solution must be adjusted with 0.1 N hydrochloric acid or citric acid to 7.0–7.4 prior to dispensing. L-lysine base is not the preferred form for dry capsule formulations in high-humidity facilities because its hygroscopicity can reduce powder flow into dosing discs and increase tablet punch sticking. For sterile filtration of a 10 g/L aqueous solution, a 0.2 µm polyethersulfone membrane is used after pH adjustment and the solution is protected from atmospheric carbon dioxide to avoid carbonate haze. Endotoxin control for parenteral-grade free-base lysine is typically set below 2.5 EU/g, with bioburden below 100 CFU/g.
Feed manufacturers replacing L-lysine sulfate with free-base lysine in a 1.0% premix encounter two immediate differences: lysine concentration per unit mass increases from approximately 51–55% to 98.5–101.0% on the dried basis, and the alkaline surface pH of the free base promotes moisture uptake and particle fusion in storage. The addition rate must be recalculated because the same weight of free-base lysine delivers roughly 1.8–2.0 times the lysine equivalent of the sulfate product. In a 500 kg horizontal ribbon blender with a spray bar fitted with twin-fluid nozzles, the free base can be introduced as a liquid to the post-ribbon discharge conveyor. If dry incorporation is required, the product should be pre-blended with 2% w/w silica conditioner and added during the final 90 seconds of mixing to limit shear-generated heat. Failure to manage moisture produces agglomerates that segregate in bucket elevators and cause variation in finished feed lysine content exceeding ±10% of target.
Release testing for free-base lysine employs titration or HPLC against a reference standard with a method repeatability of ±0.5% relative standard deviation. Microbiological limits for food-grade product are typically total aerobic microbial count ≤1000 CFU/g, yeast and mold ≤100 CFU/g, and absence of Escherichia coli in 25 g. Heavy metals are determined by atomic absorption spectrometry or inductively coupled plasma mass spectrometry after acid digestion. The free base should never be stored adjacent to volatile acids such as acetic acid or concentrated hydrochloric acid because vapor-phase absorption forms surface salts that alter pH and increase chloride. Stored material should be re-tested for pH and loss on drying after each 90-day interval in tropical warehouse conditions.
