| HS Code | 451219 |
| Productname | GLDA-4NA |
| Chemicalname | Tetrasodium N,N-bis(carboxymethyl)-L-glutamate |
| Synonyms | Tetrasodium glutamate diacetate; GLDA tetrasodium salt; N,N-bis(carboxymethyl)-L-glutamic acid tetrasodium salt |
| Casnumber | 51981-21-6 |
| Ecnumber | 257-573-7 |
| Molecularformula | C9H9NNa4O8 |
| Molecularweight | 351.12 g/mol |
| Physicalform | Aqueous solution or solid powder |
| Appearance | Clear to slightly yellow liquid or white powder |
| Assay | 47-49% as GLDA-4NA in aqueous solution; ≥99% in solid form |
| Ph | 11.0-12.5 (1% aqueous solution) |
| Density | 1.30-1.35 g/cm3 at 20°C (47% aqueous solution) |
| Watersolubility | Soluble in water |
| Biodegradability | Readily biodegradable |
| Chelatingproperty | Strong chelating agent for calcium, magnesium, iron, and other metal ions |
As an accredited GLDA-4NA factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | GLDA-4NA is supplied in 25 kg polyethylene-lined woven bags, 250 kg fiber drums, or 1,000 kg IBC totes. |
| Container Loading (20′ FCL) | 20′ FCL GLDA-4NA liquid chelating agent: palletized drums/IBCs, shrink-wrapped, securely strapped, and stowed for safe ocean export. |
| Shipping | GLDA-4NA (tetrasodium glutamate diacetate) is normally shipped as a non-hazardous, non-regulated chemical. It requires no UN number, hazard class, or packing group. Use appropriate closed containers, keep cool and dry, protect from freezing, and follow SDS labeling. Not classified as dangerous goods by DOT, IATA, or IMDG. |
| Storage | Store GLDA-4NA in tightly closed original containers in a cool, dry, well-ventilated area. Protect from moisture, heat, direct sunlight, and freezing. Keep away from strong oxidizers, acids, and bases. Maintain clear labeling, avoid dust or spills, and use secondary containment where required. Inspect containers regularly, follow the SDS and local regulations. Store separately from food, feed, and incompatible materials. |
| Shelf Life | GLDA-4NA typically has a shelf life of about 24 months when stored sealed in a cool, dry place, away from sunlight. |
Phosphate-free automatic dishwashing tablets compacted on rotary tablet presses require a builder that retains calcium-binding capacity through the humid pre-wash interval and the main wash plateau at 50–65°C. GLDA-4NA is dosed at 4–12 wt% active basis in finished tablets and 1.5–6 wt% active basis in polyvinyl-alcohol pouch gels, the exact level being set by local water hardness up to 375 mg/L CaCO₃ and by the enzyme/bleach package. In a typical solid production route, GLDA-4NA powder is pre-blended with sodium carbonate, sodium percarbonate, and sodium disilicate in a ploughshare mixer at 25–40 rpm, followed by compaction on a rotary press at 15–30 kN compression force. For gel pouches, a concentrated nonionic surfactant phase is prepared in a vacuum mixer at 40–50°C, and GLDA-4NA is post-added after neutralization to avoid pH shock. Terminal product forms are multi-layer tablets and water-soluble polyvinyl-alcohol pouches with separate enzyme and bleach compartments. Compliance is defined by EU Regulation EU 259/2012 limiting phosphate to 0.3 g phosphorus per standard dose, Regulation EC 648/2004 for detergent ingredient labeling, OECD 301B ready biodegradability with >60% mineralization in 28 days, and REACH registration. At tablet loading above 8 wt%, storage at relative humidity above 60% may cause surface caking from hygroscopic fines; moisture-barrier laminate film or tablet coating is required.
Hot 2% NaOH clean-in-place solutions sprayed through rotary spray balls at 1.5–2.5 m/s in dairy evaporators and brewery fermenters produce calcium oxalate and protein-mineral deposits on AISI 316L stainless steel when hardness cations are present in the final rinse water. GLDA-4NA is formulated into alkaline CIP concentrates at 2–5 wt% active and applied at 0.2–1.0 wt% active in the circulating use solution; the chelant is injected into the caustic recirculation tank after the initial prerinse to avoid dilution shock. The cleaning sequence is 20–40 min recirculation at 70–85°C, followed by an intermediate water rinse and, if necessary, an acid descale step for calcium carbonate or silicate deposits. The terminal product forms are single-use alkaline CIP concentrates, bottled additive canisters for dairy silo cleaning, and bottle-washer scale-control additives. Compliance for food and beverage plant detergents is assessed under 21 CFR 178.1010 where sanitizing solutions follow the detergent rinse, Regulation EC 648/2004 for detergent classification, and REACH Annex VII. The operational boundary is that GLDA-4NA does not dissolve silicate-based scale; acid descalers are required for aluminosilicate deposits. Avoid blending the chelant with chlorine-based sanitizers at pH below 4, because chelated transition metals can accelerate oxidizer decomposition and produce oxidative by-products.
When carbonate scale removal is required in production tubing with low hydrogen sulfide partial pressure, GLDA-4NA is applied as a pH-buffered dissolver for calcium carbonate and iron carbonate scale without relying on strong mineral acid. The treatment fluid is prepared by diluting a 47–50% active GLDA-4NA solution to 10–25 vol% in filtered seawater or 2 wt% KCl brine, with pH adjusted to 4.0–6.0 using hydrochloric acid or sodium hydroxide before pumping. The fluid is bullheaded or placed through coiled tubing and shut in for 6–24 h at bottomhole temperatures of 60–120°C; return streams are monitored for dissolved calcium, pH, and residual chelant before neutralization and disposal. Terminal product types include one-pack carbonate scale dissolvers, iron-control additives for matrix acidizing treatments, and casing cleanout fluids. Regulatory and compliance documentation includes OSPAR HOCNF for offshore chemical use, OECD 306 seawater biodegradability screening, and REACH registration. The operational boundary is defined by scale type: published data for barium sulfate or strontium sulfate dissolution with GLDA-4NA is limited, and such scales require DTPA/EDTA-based dissolvers or mechanical removal. Hydrogen sulfide generated during iron sulfide dissolution must be scavenged if sour conditions are encountered.
Mechanical pulp bleaching with alkaline hydrogen peroxide at 60–75°C and pH 10.5–11.5 requires selective chelation of manganese, iron, and copper before the oxidative stage because these metals catalyze peroxide decomposition and reduce brightness development. GLDA-4NA is added at 0.2–1.0 kg/t oven-dry pulp in the chelation stage. The process sequence is screw-press dewatering to 28–32% consistency, dilution to 8–12% consistency, chelant addition at 50–60°C and pH 4.5–6.0, retention for 10–20 min, and then addition of hydrogen peroxide and sodium hydroxide to the bleach tower. Terminal product forms are bleached thermomechanical pulp and chemimechanical pulp for lightweight coated papers, tissue, and board. Compliance for food-contact paper is covered by 21 CFR 176.170 and EU Framework Regulation EC 1935/2004; brightness is measured according to ISO 2470-1:2016. The pH boundary is critical: pre-treatment above 7.0 precipitates manganese hydroxide and reduces chelation efficiency; control at 5.0–5.5 maintains metal solubility.
Liquid micronutrient fertilizer concentrates containing ferric, zinc, or manganese ions require a chelator that prevents hydroxide precipitation at pH 4.0–6.0 and remains effective in hard-water fertigation stock solutions. GLDA-4NA is added at 2–6 wt% active in the final liquid concentrate, corresponding to a metal-to-chelator molar ratio of 1:1 to 1:1.1 for iron. Production involves dissolving metal sulfate monohydrates in acidified water at 50–60°C, adding GLDA-4NA under slow agitation, adjusting pH with potassium hydroxide, and filtering before packaging. The terminal product forms are liquid iron, zinc, and manganese chelate concentrates for fertigation and foliar application. Compliance falls under EU Fertilising Products Regulation (EU) 2019/1009 and REACH. Published field data for GLDA-4NA in long-term soil persistence is limited, and compatibility with high-bicarbonate irrigation water should be evaluated before large-scale use.
During continuous pad-steam bleaching of cotton single jersey, localized pinhole damage occurs when ferric ion concentration exceeds 0.5 mg/L in the pad bath and no chelator is present. GLDA-4NA is introduced at 0.3–1.0 g/L into the pad liquor containing 35% hydrogen peroxide at 20–30 mL/L and sodium hydroxide at 5–10 g/L. The fabric is padded to 80–100% wet pickup, steamed at 98–102°C for 12–20 min, and then washed at 80–90°C to remove silicate and chelant residues. Terminal product types include bleached cotton knits, terry towels, socks, and medical textiles. Compliance is assessed against ZDHC MRSL 3.1 restricted substance limits and OEKO-TEX® Standard 100 criteria for residual heavy metals and formaldehyde; ISO 3071:2020 is used for aqueous extract pH. Dosing above 1.0 g/L can over-stabilize peroxide and reduce whiteness; a peroxide residual check after 10 min of steaming determines whether the oxidant concentration should be increased.
Soap bar production on twin-screw plodders and vacuum extruders requires a chelating agent that remains active in the alkaline soap matrix at pH 9–10 and prevents transition-metal-induced rancidity, discoloration, and hard-water soap scum. GLDA-4NA is added at 0.05–0.3 wt% active in finished bar soap and 0.1–0.5 wt% active in liquid body wash or sulfate-free shampoo systems. In soap manufacturing, the chelant is metered into the amalgamator after vacuum drying or into the crutcher before saponification; in liquid syndets it is post-added at 40–50°C after neutralization to avoid pH shock. Terminal product forms include transparent glycerin soap bars, syndet body bars, liquid body washes, and sulfate-free shampoo systems. Compliance is defined by Regulation EC 1223/2009 for cosmetic products, ISO 16128-1:2016 for natural-origin index calculation, and OECD 301B for ready biodegradability. At addition above 0.5 wt% in low-salt surfactant systems, GLDA-4NA can shift the salt curve and reduce viscosity; a cold-process sample should be prepared to verify rheology before scale-up.
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GLDA-4NA is the tetrasodium salt of N,N-bis(carboxylatomethyl)-L-glutamic acid, with molecular formula C9H9NNa4O8, molecular weight 351.13 g/mol and CAS 51981-21-6. The product is supplied as two physical models: GLDA-4NA-47L, an aqueous solution with active content 47.0–49.0 wt%, and GLDA-4NA-G, a dry granular material with total solids above 95 wt%. The aqueous grade is a clear pale-yellow to amber liquid with density 1.29–1.33 g/cm³ at 20 °C, measured by ASTM D4052-22, and pH 10.5–11.5 at 1% aqueous dilution, measured by ASTM E70-19. The product functions as an aminocarboxylate chelating agent for alkaline cleaning, water treatment, scale dissolution and detergent building. Because a single molecule contains one tertiary amine donor and four carboxylate oxygen donors, it binds divalent and trivalent metal ions at 1:1 molar stoichiometry in most commercial applications. The theoretical calcium-binding capacity of the anhydrous salt is 285 mg CaCO3 per gram active GLDA-4Na, equivalent to 134 g CaCO3 per kg of 47.0 wt% solution. These values are calculated from molecular weight and stoichiometry rather than from single-dose bottle tests.
| Parameter | Typical value | Determination method |
|---|---|---|
| Appearance at 25 °C | Clear pale-yellow to amber liquid | Visual inspection against white background |
| Active content as GLDA-4Na | 47.0–49.0 wt% | Potentiometric Cu(II) complexometric titration using Cu ion-selective electrode |
| Density at 20 °C | 1.29–1.33 g/cm³ | ASTM D4052-22 digital density meter |
| pH, 1% aqueous solution at 25 °C | 10.5–11.5 | ASTM E70-19 glass electrode |
| Viscosity at 25 °C | 40–100 mPa·s | ISO 2555:2018 Brookfield LV, spindle 3, 60 rpm |
| Theoretical CaCO₃ binding capacity | 134 g/kg of 47% solution | Calculated from 351.13 g/mol and 1:1 stoichiometry |
| Sodium contribution from active GLDA-4Na | 123 g Na/kg of 47% solution | Calculated from molecular composition |
Liquid storage should use 316L stainless steel or high-density polyethylene tanks. Low-temperature storage below 0 °C may raise viscosity significantly; controlled thawing with recirculation is required. The concentrate is alkaline and should not be left in prolonged contact with aluminum or zinc dosing components because corrosive attack can generate hydrogen and reduce chelant activity.
Dose calculation for GLDA-4Na begins with the 1:1 molar binding ratio toward calcium and magnesium. The theoretical mass dose of anhydrous GLDA-4Na is 3.51 gram active salt per gram CaCO3, derived from the quotient of 351.13 g/mol and 100.09 g/mol. The equivalent dose for the 47.0 wt% aqueous solution is approximately 7.47 gram liquid per gram CaCO3. For a feedwater containing 300 mg/L CaCO3, the theoretical active GLDA-4Na demand is 1.05 kg/m³, corresponding to 2.24 kg/m³ of GLDA-4NA-47L. Dynamic tube-blocking testing on a recirculating capillary rig usually requires 10–20 % molar excess above calcium stoichiometry when no polymeric scale inhibitor is present; the exact surplus is determined by thermal steel-surface deposition and turbidity measurement.
Complexometric titration of the working bath with copper(II) ion-selective electrode permits residual chelant control without pH indicator interference from colored industrial liquors. The endpoint corresponds to the disappearance of free Cu(II), reflecting intact aminocarboxylate functionality. In mixed-hardness water, Fe(III) is preferentially bound over calcium and magnesium due to higher complex stability, but the stoichiometric excess must cover the sum of hardness metals plus redox-active metals. At pH below 5, proton competition reduces available carboxylate sites, making GLDA-4Na unsuitable as the sole scale-control agent in strongly acidic descaling baths unless blended with acid-stable chelants or organic acids.
Compared with EDTA-4Na, GLDA-4Na has a lower anhydrous molecular weight and therefore a higher theoretical calcium capacity per unit mass. The calculated value of 285 mg CaCO3/g for GLDA-4Na compares with 263 mg CaCO3/g for EDTA-4Na, a difference of approximately 8 % by mass. NTA-3Na and MGDA-3Na exhibit higher mass-based calcium capacities because of lower molecular weights; however, NTA-3Na is restricted in certain applications due to toxicity and regulatory status, and MGDA-3Na has a different sodium and builder alkalinity contribution. Published stability constants for GLDA-4Na in the presence of calcium are lower than those of EDTA-4Na at neutral pH, but the operational advantage is high solubility and stability in alkaline oxidizing systems.
In continuous tunnel warewashers operating at 55–65 °C wash and 82 °C rinse, GLDA-4NA-47L is metered into the wash tank through solenoid diaphragm pumps with Viton seals. Typical active doses are 0.2–1.0 g/L for softened feedwater and 0.8–2.5 g/L for feed hardness 200–400 mg/L CaCO3. The product can be combined with sodium carbonate or citrate builder without precipitation; however, carbonate alkalinity above 1000 mg/L may require increased chelant addition to control calcite oversaturation at heating elements. Field failure modes include glass film formation when the chelant dose falls below the stoichiometric calcium load and rinse-aid carryover depresses soil suspension. This condition is corrected by complexometric titration of the wash liquor and by maintaining a chelant surplus of 1–2 mmol/L in the tank.
When bottle-washing lines process heavily printed labels and aluminium closure residues, the replacement of EDTA-4Na by GLDA-4Na at equal active molar chelant dose maintains label-stock separation in 1.5–3.0 wt% NaOH baths at 70–80 °C. GLDA-4Na is added to the hot caustic tank by conductivity-controlled metering, and the final bath is held at 1–2 mmol/L surplus chelant. The product reduces free iron in caustic and lowers iron staining on paper labels. Published data for high-caustic stability beyond 48 h at 80 °C are formulation-specific and should be verified by Cu(II) titration and NaOH titration per shift. Glass corrosion in bottle washers should be separately evaluated because alkaline chelants can alter silica dissolution rates at prolonged contact times.
In textile pretreatment, GLDA-4Na is introduced into alkaline scouring and hydrogen peroxide bleaching baths to control iron and hardness. The chelant improves peroxide stability by sequestering Fe(III) and Cu(II) ions that catalyze peroxide decomposition. Continuous pad-steam processing with equal molar replacement of EDTA-4Na maintains whiteness in trials when the bath is set at pH 10.5–12.0 with NaOH and GLDA-4Na is dosed at 2–5 g/L depending on fabric ash content and incoming water hardness. Residual peroxide is monitored by iodometric titration, and residual chelant is determined by Cu(II) titration. The product is not a direct substitute for silicate in peroxide bleaching and should not be used to eliminate silicate stabiliser without revalidation of fiber strength and degree of polymerization.
The substitution of EDTA-4Na by GLDA-4Na in hypochlorite-containing cleaners depends on oxidant concentration, matrix pH and storage temperature. In alkaline machine dishwashing and hard-surface cleaning, EDTA-4Na is oxidised at the amine sites and loses chelation performance, whereas GLDA-4Na retains Fe(III) and calcium binding capacity for longer contact periods. Screening in 5.0 wt% NaOCl at pH 12 and 25 °C indicates that GLDA-4Na residual chelant remains measurable after 24 h by Cu(II) titration. Extended storage in hypochlorite concentrates above 10 wt% NaOCl can oxidise the tertiary amine and reduce performance; published data for all liquid detergent matrices are limited. The recommended practice is to keep the chelant and hypochlorite in separate dosing lines and mix only in the dilute working bath. Direct pre-mixing of GLDA-4Na with peracetic acid or hydrogen peroxide at acidic pH should be avoided because exothermic degradation of the chelant can occur. Any oxidative stability claim should be supported by iodometric titration of available chlorine and residual chelant over the required shelf life.
Ready biodegradability of GLDA-4Na is demonstrated by OECD 301B CO₂ evolution according to the 10-day window pass criterion. The parent molecule mineralises in aerobic activated sludge, so it does not introduce the persistent chelant load associated with EDTA in receiving waters. Acute aquatic toxicity endpoints are established using OECD 202 Daphnia immobilisation and OECD 203 fish tests; exact endpoint values should be taken from the supplier’s REACH registration because they vary with water hardness, salt form and test species. The product contains no phosphorus and does not contribute phosphate to wastewater. The sodium content should be included in total salt balance for membrane permeate and cooling-water blowdown calculations, and the nitrogen content of the anhydrous salt is 3.99 wt%.
| Attribute | GLDA-4Na | EDTA-4Na | NTA-3Na | MGDA-3Na |
|---|---|---|---|---|
| Anhydrous molar mass | 351.13 g/mol | 380.2 g/mol | 257.1 g/mol | 273.1 g/mol |
| Theoretical CaCO₃ binding per gram active salt | 285 mg/g | 263 mg/g | 389 mg/g | 366 mg/g |
| Ready biodegradability, OECD 301B | Pass, ≥60% mineralisation | Not readily biodegradable | Variable; method-dependent | Pass, ≥60% mineralisation |
| Oxidative stability in alkaline hypochlorite | High; limited in oxidising acids | Low; amine oxidation | Moderate; strong oxidation risk | High; limited in oxidising acids |
| Primary raw-material basis | L-glutamic acid, fermentation-derived in many grades | Ethylenediamine, formaldehyde, sodium cyanide | Ammonia, formaldehyde, sodium cyanide | Petrochemical or bio-based methylglycine feedstocks |
| Regulatory constraints | REACH registered; no harmonised CMR classification | Poor biodegradability; effluent monitoring considerations | Restrictions in some EU applications due to historical toxicological concern | REACH registered; readily biodegradable |
Within high-alkali automatic dishwashing, GLDA-4Na and MGDA-3Na are often considered as direct alternatives. MGDA-3Na has a lower molecular weight and therefore a higher theoretical CaCO3 capacity per gram. GLDA-4Na contributes four sodium equivalents per molecule and therefore increases builder alkalinity; this can be advantageous in carbonate-based systems but must be accounted for in low-alkalinity liquid detergents. The choice between GLDA-4Na and MGDA-3Na should be based on cold-water clarity, freeze-thaw stability, sodium sensitivity and any renewable-carbon labelling requirement. Where renewable-carbon claims are made, the carbon-14 content is verified by ASTM D6866-22 on the specific commercial batch.
Dry GLDA-4NA-G is used when liquid dosing points are unavailable or when the formulation is moisture-sensitive. The granulate is hygroscopic and should be stored at relative humidity below 60 %; residual moisture is measured by Karl Fischer titration per ASTM E203-16. In powder detergent post-tower addition, GLDA-4NA-G is added after the spray-drying step at 5–30 wt% of finished powder. The powder is introduced through a rotary valve into a low-shear ribbon mixer; high-shear paddle mixing above 40 °C can promote caking. The liquid grade GLDA-4NA-47L can also be sprayed onto a sodium carbonate or sodium sulfate carrier in a continuous horizontal paddle mixer at 50–70 °C; the outlet moisture should be maintained below 12 wt% to prevent lump formation. Granule particle size distribution measured by sieve analysis according to ISO 3310-1 is typically controlled to 0.2–1.0 mm for automatic dispensing systems.
When dry GLDA-4NA-G is exposed to high-humidity air above 60 % relative humidity, surface absorption can create a viscous layer on storage bins and screw conveyors. This operational boundary is more severe than for sodium sulfate or carbonate carriers and must be addressed by nitrogen blanketing or dehumidified transfer air in coastal production sites. If the powder is compacted into tabs, tablet hardness testing with a Schleuniger apparatus should be correlated with residual moisture and press force; brittle failure is observed when moisture exceeds 8 wt% and press dwell time is too short. These constraints do not apply to the aqueous grade, which is preferred for automated liquid dosing in institutional laundry and warewash installations.
