The Role, Selection, and Validation of Chelating Agents in Daily Chemical Formulations
The Role, Selection, and Validation of Chelating Agents in Daily Chemical Formulations
1 Why Metal Ions Affect the Stability of Daily Chemical Formulations
1.1 Main Sources of Metal Ions
Most daily chemical products are water-based systems. Water, inorganic salts, surfactants, plant extracts, fragrances, colorants, fillers, production equipment, storage tanks, pipelines, and packaging materials may all introduce metal ions into a formulation. In daily chemical formulations, the metal ions that require particular attention mainly include:
Metal ion | Main source | Main risk |
Ca²⁺, Mg²⁺ | Hard water, inorganic salts, impurities in certain raw materials | Reduced cleaning power, reduced foam, precipitation, scale, spotting |
Fe²⁺, Fe³⁺ | Water, equipment, pipelines, plant extracts, pigment powders | Yellowing, fading, off-odor, accelerated oxidation |
Cu²⁺ | Water, equipment, pipelines, impurities in certain raw materials | Fragrance deterioration, oxidative discoloration, reduced active ingredient content |
Mn²⁺ | Water, inorganic raw materials, certain mineral impurities | Instability of oxidative systems, color change |
Ba²⁺, Sr²⁺ | Specific inorganic raw materials or water quality | Precipitation of poorly soluble salts, scaling risk |
These metal ions are usually present at very low levels, but they can have a noticeable impact in a formulation. Transition metal ions such as Fe³⁺ and Cu²⁺, even in trace amounts, may catalyze oxidation reactions and cause changes in product color, odor, and active ingredients during storage.
1.2 Typical Formulation Problems Caused by Metal Ions
The impact of metal ions on daily chemical products is mainly reflected in four types of formulation issues.
① Fluctuations in cleaning performance caused by hard water.
Ca²⁺ and Mg²⁺ can interact with anionic surfactants, soap-based ingredients, carbonates, and other components, reducing the utilization efficiency of effective cleaning ingredients. This may lead to reduced foam, decreased detergency, fabric graying, and a residual feel after rinsing.
② Precipitation, turbidity, and scale.
Metal ions can easily form poorly soluble substances with fatty acid salts, carbonates, silicates, phosphates, or certain anionic components in the formulation. This may cause turbidity, flocculation, sediment at the bottom of the bottle, clogged spray nozzles, or water spots and scale marks on treated surfaces.
③ Metal-catalyzed oxidation.
Fe³⁺, Cu²⁺, and Mn²⁺ may accelerate the oxidation of fragrances, colorants, oils, plant extracts, peroxides, and certain active ingredients, resulting in yellowing, off-odor, fading, and loss of activity.
④ Impact on preservative system stability.
Metal ions may interfere with the preservative system or provide certain nutrients for microbial growth. Chelating agents can serve as auxiliary stabilizing factors in preservative systems, but they cannot replace preservatives or preservative challenge testing.
1.3 Core Value of Chelating Agents
The core function of chelating agents is to control metal ions. By binding metal ions such as Ca²⁺, Mg²⁺, Fe³⁺, Cu²⁺, and Mn²⁺, chelating agents reduce the free activity of these ions, thereby minimizing their impact on cleaning power, foam, appearance, odor, color, preservation, and shelf-life stability.
In daily chemical formulations, chelating agents are usually neither primary cleaning ingredients nor preservatives. However, they can improve formulation stability under different water qualities, raw material batches, and storage conditions. Chelating agents are functional additives used at low levels but with a high impact on formulation performance.
2 What Chelating Agents Are and How They Work
2.1 Definition of Chelating Agents
Chelating agents are compounds that can form stable complexes with metal ions. Their molecules usually contain coordination groups such as carboxyl, amino, hydroxyl, phosphonic acid, or phosphate ester groups, allowing them to bind metal ions through multiple coordination sites.
Compared with single-point coordination, metal complexes formed through multi-point coordination are generally more stable. In daily chemical formulations, the purpose of using chelating agents is not to “remove” metal ions from the system, but to convert free metal ions into relatively stable and less reactive metal-chelating agent complexes. This can be simplified as:
Mⁿ⁺ + chelating agent → metal-chelating agent complex
where Mⁿ⁺ represents metal ions such as Ca²⁺, Mg²⁺, Fe³⁺, and Cu²⁺.
2.2 Mechanism of Action of Chelating Agents
The role of chelating agents in daily chemical formulations can be understood in three steps.
Step 1: Identifying and binding metal ions.
Coordination groups on the chelating agent molecule bind with metal ions to form complexes. Different chelating agents have different binding abilities for different metal ions. For example, some are better at controlling Ca²⁺ and Mg²⁺, while others are more suitable for controlling Fe³⁺ and Cu²⁺.
Step 2: Reducing the activity of free metal ions.
Once metal ions are bound by a chelating agent, their ability to participate in precipitation, oxidation, catalysis, and disruption of surfactant systems is reduced. For a formulation, what truly matters is not the total amount of metal ions, but the effective activity of free metal ions.
Step 3: Reducing side reactions caused by metal ions.
When Ca²⁺ and Mg²⁺ are controlled, the interference of hard water with cleaning power and foam is reduced. When Fe³⁺ and Cu²⁺ are controlled, the risks of oxidative discoloration, fragrance deterioration, and loss of active ingredients are reduced. When the chance of metal ions forming poorly soluble salts decreases, turbidity, precipitation, scale, and spotting are also reduced accordingly.
2.3 Chelating Performance Must Be Evaluated Under Formulation Conditions
The ability of a chelating agent to form a complex with metal ions is often expressed using a stability constant. Under the same test conditions, a higher stability constant generally indicates a more stable metal-chelating agent complex. However, in real formulations, the actual performance of a chelating agent is also affected by the following factors:
Influencing factor | Impact on chelating performance |
pH | Affects the ionization state of the chelating agent and its metal-binding ability |
Ionic strength | High-salt systems may alter chelation equilibrium and solubility |
Temperature | Affects complex stability, solubility, and precipitation risk |
Competing ions | Multiple metal ions present at the same time may compete for the chelating agent |
Surfactant system | Affects transparency, viscosity, foam, and compatibility |
Chelating agent dosage | Too low a dosage may fail to effectively control metal ions; too high a dosage may affect cost or system stability |
3 Four Core Problems Chelating Agents Solve in Daily Chemical Products
3.1 Improving Cleaning Power and Foam Stability Under Hard-Water Conditions
Ca²⁺ and Mg²⁺ in hard water can reduce the actual efficiency of surfactants. In formulations containing anionic surfactants or soap-based ingredients, Ca²⁺ and Mg²⁺ may form poorly soluble substances with surfactants or fatty acid salts, reducing foam, lowering cleaning power, and causing residue after washing.
Chelating agents preferentially bind Ca²⁺ and Mg²⁺, reducing side reactions between hard-water ions and surfactants. As a result, they improve product performance consistency under different water-quality conditions. This function is especially important in the following products:
Product type | Main problem | Role of chelating agent |
Laundry liquid detergent | Fluctuating detergency, fabric graying, inorganic residue | Controls Ca²⁺ and Mg²⁺ and improves surfactant utilization |
Dishwashing liquid | Reduced foam, reduced grease removal, rinse residue | Reduces hard-water interference and improves foam and cleaning stability |
Shampoo and body wash | Insufficient foam, changes in rinse feel | Reduces the impact of hard-water ions on the surfactant system |
Hard-surface cleaner | Scale, soap scum, spotting | Controls calcium and magnesium ions and reduces inorganic residue |
For enzyme-containing laundry detergents or automatic dishwasher detergents, the effect of chelating agents on enzyme stability also needs to be considered during selection. Some enzymes require metal ions to maintain structural stability. Chelating agents that are too strong or used at excessive levels may affect enzyme systems, so confirmation through formulation testing is necessary.
3.2 Reducing Turbidity, Precipitation, Scale, and Spotting
Turbidity and precipitation in daily chemical formulations are often related to the formation of poorly soluble salts by metal ions. Ca²⁺ and Mg²⁺ can form precipitates with carbonates, fatty acid salts, silicates, phosphates, and other components. Fe³⁺ may also form darker-colored complexes or deposits with certain anions or plant-derived components. These problems are commonly seen in the following situations:
Problem observed | Common system | Main cause |
Low-temperature turbidity | Transparent dishwashing liquids, hand soaps, shampoos | Combined effects of metal ions, electrolytes, and surfactant systems |
Sediment at the bottom of the bottle | Alkaline cleaners, soap-based systems | Formation of calcium/magnesium salts or metal soaps |
Spray nozzle clogging | Bathroom cleaners, kitchen cleaners | Inorganic salt deposits or scale formation |
Surface spotting | Glass cleaning, dishwashing, bathroom cleaning | Hard-water ion residue or scale deposition |
3.3 Inhibiting Metal-Catalyzed Oxidation and Reducing Yellowing and Off-Odor Risks
Transition metal ions such as iron, copper, and manganese, including different valence states such as Fe²⁺/Fe³⁺ and Cu⁺/Cu²⁺, can readily participate in redox cycles. They can accelerate the oxidation of fragrances, colorants, oils, plant extracts, peroxides, and certain active ingredients. Typical manifestations include:
Manifestation | Possible cause |
Product yellowing or darkening | Oxidation catalyzed by Fe³⁺ and Cu²⁺ |
Fragrance off-odor | Metal ions promoting fragrance oxidation |
Colorant fading or color change | Interaction between metal ions and colorants or oxidative systems |
Loss of active ingredients | Accelerated degradation of oxidation-sensitive ingredients |
Peroxide decomposition | Metal-ion-catalyzed decomposition |
In these systems, the role of chelating agents is to reduce the catalytic activity of metal ions such as Fe³⁺, Cu²⁺, and Mn²⁺. They cannot replace antioxidants, but they can work together with antioxidants, pH regulators, and light-protective packaging to improve formulation stability.
3.4 Supporting Preservative System Stability Without Replacing Preservatives
Their role mainly comes from two aspects. First, they reduce the level of certain metal ions available to microorganisms and may increase microbial sensitivity to the preservative system by chelating divalent metal ions needed to stabilize the outer membrane or cell wall. Second, they reduce the interference of metal ions with preservatives and the formulation system.
EDTA, or ethylenediaminetetraacetic acid, and its salts are commonly used as chelating agents in personal care products and cosmetics, and they are often used to help improve preservative system stability. Formulations containing chelating agents still need to undergo preservative testing. This is especially important for products that reduce the level of traditional preservatives, use mild preservative systems, or contain plant extracts. Preservative safety cannot be judged solely by the addition of a chelating agent.
4 Comparison of Common Chelating Agents
4.1 Typical Chelating Agents and Metal Ion Control Agents
Chelating agents and metal ion control agents commonly used in the daily chemical industry include EDTA, DTPA, MGDA, GLDA, citrates, sodium gluconate, sodium phytate, and HEDP. Their key differences are not limited to chelating strength, but also include applicable pH range, solubility, environmental attributes, formulation compatibility, and cost structure.
Type | Common product | Key characteristics | Main advantages | Main limitations | Suitable applications |
Aminocarboxylates | EDTA, disodium EDTA, tetrasodium EDTA | Strong overall chelating ability; mature application history | Low dosage, low cost, good stability; effective on Ca²⁺, Mg²⁺, Fe³⁺, and Cu²⁺ | Weak biodegradability; not suitable for formulations emphasizing biodegradability or EDTA-free positioning | Hair care, skin care, liquid cleaners, conventional stabilization systems |
Aminocarboxylates | DTPA, or diethylenetriaminepentaacetic acid, and its salts | Multiple coordination sites; strong control of transition metal ions such as Fe³⁺ and Cu²⁺ | Suitable for systems with high metal ion interference or oxidation sensitivity | Poor biodegradability and high environmental persistence; usually higher cost than EDTA | Bleaching systems, peroxide systems, professional cleaning |
Biodegradable aminocarboxylates | MGDA, or methylglycinediacetic acid, and its salts | Good control of Ca²⁺ and Mg²⁺ | Good biodegradability; suitable for green cleaning products | Unit price is usually higher than EDTA; cost needs to be calculated based on effective active content | Laundry liquid detergents, dishwashing detergents, hard-surface cleaners |
Biodegradable aminocarboxylates | GLDA, or glutamic acid N,N-diacetic acid, and its salts | Friendly to green positioning; good applicability in liquid formulations | Good formulation compatibility; suitable for EDTA-free systems | Chelating strength is usually lower than EDTA; cannot be substituted on an equal-dosage basis; dosage needs to be confirmed through formulation testing | Liquid |
Hydroxycarboxylic acids | Citric acid, sodium citrate | Provides pH adjustment, buffering, and weak chelation | Low cost and high consumer acceptance | Limited chelating ability; not suitable for strong metal control | Mildly acidic hair and skin care, skin care, mild cleaning, auxiliary stabilization |
Polyhydroxy carboxylates | Sodium gluconate | Good water solubility; stable performance in alkaline systems | Mild, with certain dispersing and chelating effects | Weaker control of strong-risk metals such as Fe³⁺ and Cu²⁺ compared with EDTA and DTPA | Alkaline cleaners, hard-surface cleaning, liquid detergents |
Naturally derived friendly type | Phytic acid, sodium phytate | Polyphosphate ester structure capable of binding multivalent metal ions | Suitable for natural, mild, and EDTA-free formulations | Relatively high cost; significantly affected by pH and ionic strength | Skin care, hair care, naturally positioned products |
Phosphonate metal control agents | HEDP, or 1-hydroxyethylidene-1,1-diphosphonic acid, and its salts | Outstanding scale inhibition, dispersion, and bleaching stabilization effects | Good scale inhibition at low dosage; suitable for highly alkaline and peroxide systems | Phosphorus-containing; environmental and regulatory requirements need attention | Automatic dishwashing, hard-surface cleaning, bleaching stabilization systems |
Inorganic phosphate builders | Sodium tripolyphosphate; pentasodium tripolyphosphate; STPP | Complexes Ca²⁺ and Mg²⁺; provides water softening, dispersion, buffering, and detergency-building effects | Good hard-water control, clear detergency-building effect, mature technology, relatively low cost | Phosphorus-containing; phosphate-free requirements, environmental concerns, and target-market regulations need attention | Laundry powders, heavy-duty detergents, automatic dishwasher powders, industrial cleaners |
STPP is an important traditional inorganic phosphate builder in detergents. It can complex Ca²⁺ and Mg²⁺, reduce hard-water interference, and provide dispersion, buffering, and anti-redeposition effects. Unlike small-dosage organic chelating agents such as EDTA, MGDA, and GLDA, STPP is more commonly used in laundry powders, heavy-duty detergents, automatic dishwasher powders, and industrial cleaners. Because it contains phosphorus, its use requires attention to phosphate-free formulation requirements, environmental labeling, and target-market regulations.
4.2 Key Comparison of EDTA, MGDA, and GLDA
EDTA is one of the most mature and widely used chelating agents. It has strong binding ability for a variety of metal ions, can be used at low dosages, and offers clear cost advantages. It is suitable for conventional hair care, skin care, and cleaning systems. However, EDTA is not readily biodegradable, which limits its use in green, natural, and sustainability-positioned products.
MGDA and GLDA are common biodegradable alternatives. They are widely used in hard-water control, cleaning stability, and green formulations, especially in laundry liquid detergents, dishwashing liquids, automatic dishwashing products, and hard-surface cleaners. Compared with EDTA, the advantage of MGDA and GLDA is that they better meet the needs of biodegradability, green cleaning, and environmental friendliness.
Taking the Ca²⁺ chelation stability constant as an example, commonly cited reference values in public sources show that the logK of EDTA with Ca²⁺ is about 10.6, MGDA about 7.0, and GLDA about 5.9. Numerically, EDTA has a stronger binding ability for calcium ions. However, in actual formulations, chelating performance is also affected by pH, temperature, ionic strength, competing ions, and dosage. These values are suitable for judging the general trend of chelating ability, but they should not be used as the only basis for selection. For enzyme-containing systems, green-positioned systems, or products with higher requirements for environmental attributes, MGDA and GLDA may still offer better overall advantages.
4.3 Application Characteristics of Citrates, Sodium Gluconate, Sodium Phytate, and HEDP
Citric acid and sodium citrate are more suitable as auxiliary chelating agents and pH-adjusting components. They are low in cost and widely accepted, but their metal ion control ability is limited. They are not suitable as replacements for strong chelating agents such as EDTA and DTPA in high-risk systems.
Sodium gluconate is suitable for alkaline cleaning systems and has good water solubility and certain dispersing effects. It is commonly used in hard-surface cleaning, liquid detergents, and alkaline cleaning products. However, its ability to control high-risk oxidative catalytic metals such as Fe³⁺ and Cu²⁺ should not be overestimated.
Sodium phytate is suitable for EDTA-free, naturally derived, or mild-positioned hair care, skin care, and cleansing formulations. It can bind multivalent metal ions, but its actual performance is greatly affected by pH, ionic strength, and the formulation system. Transparency, color stability, and preservative challenge testing are needed for confirmation.
HEDP is a phosphonate-based metal control agent, scale inhibitor, and dispersant. It is suitable for automatic dishwashing, hard-surface cleaning, highly alkaline cleaning, and peroxide-containing systems. When selecting HEDP, attention should be paid to its phosphorus content, target-market regulations, and environmental requirements.
5 How to Select and Validate Chelating Agents
5.1 Selection Based on Target Metal Ions
The first step in selection is to determine which type of metal ion mainly needs to be controlled. Different problems correspond to different metal ions, and the suitable chelating agents also differ.
Main problem | Priority metal ions | Selection direction |
Reduced foam and cleaning power under hard-water conditions | Ca²⁺, Mg²⁺ | EDTA, MGDA, GLDA, citrates, sodium gluconate |
Product turbidity, precipitation, scale | Ca²⁺, Mg²⁺, Ba²⁺ | MGDA, GLDA, HEDP, sodium gluconate, EDTA |
Yellowing, off-odor, fragrance deterioration | Fe³⁺, Cu²⁺, Mn²⁺ | EDTA, DTPA, GLDA, sodium phytate |
Fluctuations in preservative system performance | Fe³⁺, Ca²⁺, Mg²⁺, etc. | EDTA, GLDA, sodium phytate, citrates |
Instability of peroxide systems | Fe³⁺, Cu²⁺, Mn²⁺ | DTPA, HEDP, EDTA, MGDA |
If the main issue is reduced cleaning power caused by hard water, the ability to control Ca²⁺ and Mg²⁺ should be the key comparison. If the main issue is yellowing, off-odor, or loss of active ingredients, the ability to control Fe³⁺, Cu²⁺, and Mn²⁺ should be the focus. If the issue is scale, spotting, or precipitation, chelation, scale inhibition, and dispersion should all be considered. For bleaching or peroxide systems, chelating agents must not only control metal ions such as Fe³⁺, Cu²⁺, and Mn²⁺, but also be evaluated for their impact on oxidant stability, product appearance, and storage stability.
5.2 Selection Based on Formulation pH and System Compatibility
The effectiveness of a chelating agent is closely related to pH. The ionization state, metal-binding ability, and solubility of the same chelating agent may differ under different pH conditions.
Formulation type | Common pH range | Selection focus | Products to prioritize for evaluation |
Mildly acidic skin care, hair care, and cleansing | pH 4–6 | Mildness, transparency, preservative support, color stability | Disodium EDTA, sodium phytate, GLDA, citrates |
Neutral to weakly alkaline cleaning | pH 7–9 | Hard-water control, foam, surfactant compatibility, cost | EDTA salts, MGDA, GLDA, sodium gluconate |
Highly alkaline cleaning, automatic dishwashing | pH above 10 | Scale inhibition, dispersion, high-alkali stability, bleaching stability | MGDA, GLDA, HEDP, sodium gluconate |
System compatibility is equally important. Enzyme-containing formulations require attention to the impact of chelating agents on enzyme stability. Formulations containing cationic polymers should be checked for turbidity and precipitation. Transparent systems require attention to low-temperature precipitation. Systems containing fragrances and plant extracts should be monitored for color and odor changes. Peroxide-containing systems require attention to metal-catalyzed decomposition.
5.3 Selection Based on Product Positioning
Different product positionings have different requirements for chelating agents. Low-cost mature formulations, green cleaning formulations, natural skin care formulations, and highly stable professional cleaning formulations are not suited to the same selection approach.
Product positioning | Selection focus | Priority evaluation direction |
Cost-sensitive, mature formulations | Cost, supply stability, low dosage | Disodium EDTA, tetrasodium EDTA, citrates |
Green cleaning, biodegradable | Biodegradability, environmental attributes, hard-water control | MGDA, GLDA, sodium gluconate |
Natural or EDTA-free hair care and skin care | EDTA-free formulation compatibility, mildness, color stability | Sodium phytate, GLDA, citrates |
Strong metal control and high stability requirements | Control of Fe³⁺, Cu²⁺, and Mn²⁺ | EDTA, DTPA, HEDP |
Highly alkaline cleaning and scale-inhibition requirements | Scale inhibition, dispersion, high-pH stability | HEDP, MGDA, sodium gluconate, GLDA |
Green substitution is not a simple equal-dosage replacement. EDTA, MGDA, GLDA, sodium phytate, citrates, and sodium gluconate differ in molecular structure, effective active content, metal selectivity, and applicable pH range. If EDTA is replaced with another chelating agent, dosage, pH, stability, preservative challenge performance, and long-term storage performance should be revalidated.
5.4 Selection Table for Typical Daily Chemical Applications
Different products have different core issues, so selection should be based on actual application goals.
Application | Main problem | Priority evaluation | Notes |
Laundry liquid detergent | Hard water, fabric graying, inorganic residue, enzyme stability | MGDA, GLDA, EDTA, sodium gluconate | Enzyme-containing systems require enzyme stability testing; strong chelation should not be pursued blindly |
Dishwashing liquid | Reduced foam, fluctuating grease removal, rinse residue | Disodium EDTA, MGDA, GLDA, citrates | Focus on foam, transparency, and grease removal under hard-water conditions |
Shampoo, body wash, hand soap | Foam, rinse feel, color, fragrance, preservative stability | Disodium EDTA, GLDA, sodium phytate, citrates | Focus on mildness, transparency, low-temperature stability, and preservative challenge testing |
Skin care products | Yellowing, fragrance deterioration, plant extract stability, preservative support | Disodium EDTA, sodium phytate, GLDA | Fe³⁺ and Cu²⁺ challenge testing and long-term stability testing are recommended |
Hard-surface cleaners | Scale, soap scum, precipitation, spray nozzle clogging | MGDA, GLDA, HEDP, sodium gluconate | Highly alkaline systems require attention to scale inhibition, dispersion, and regulatory requirements |
Automatic dishwasher detergents | Hard water, glass spotting, bleaching stability, enzyme stability | MGDA, GLDA, HEDP, citrates | Enzymes, bleaching agents, scale inhibition, and environmental requirements need to be balanced |
Bleaching or peroxide systems | Metal-catalyzed decomposition, loss of activity, yellowing | DTPA, HEDP, EDTA, MGDA | Focus on controlling Fe³⁺, Cu²⁺, and Mn²⁺ and validate oxidative system stability |
5.5 Conducting Validation Tests
Chelating agent selection needs to be confirmed through formulation testing. The recommended tests can be divided into six categories.
Test item | Test purpose | Key observation indicators |
Hard-water compatibility test | Evaluates the impact of Ca²⁺ and Mg²⁺ on cleaning power, foam, and formulation appearance | Foam height and foam stability, detergency, turbidity, precipitation, rinse residue |
Metal ion spiking stability test | Evaluates formulation tolerance to metal contamination by adding Fe³⁺, Cu²⁺, and other metal ions | Yellowing, fading, off-odor, changes in active content, turbidity, precipitation |
High- and low-temperature stability test | Evaluates formulation stability risks under temperature changes | Phase separation, precipitation, turbidity, viscosity change, pH change, odor change |
Low-temperature transparency test | Evaluates precipitation, crystallization, and turbidity risks under low-temperature conditions | Turbidity change, crystals, flocculates, recovery after low-temperature exposure |
Preservative challenge test | Evaluates the effect of adding a chelating agent on the preservative efficacy of the established preservative system | Changes in microbial counts at different time points, log reduction values, whether preservative challenge criteria are met |
Overall cost-performance evaluation | Compares actual application cost when different chelating agents achieve the same target effect | Dosage required to achieve the target effect, unit product cost, degree of stability improvement, overall cost-effectiveness |
Blank groups and control groups should be included in testing. The blank group contains no chelating agent, the control group uses a mature existing solution, and the new formula uses the candidate chelating agent. Only by comparing the samples under the same hard-water conditions, pH, temperature, and storage conditions can it be determined whether the differences are caused by the chelating agent itself.
5.6 Summary
The core value of chelating agents in daily chemical formulations is metal ion control. By reducing the free activity of metal ions such as Ca²⁺, Mg²⁺, Fe³⁺, Cu²⁺, and Mn²⁺, they reduce hard-water interference, precipitation and turbidity, scale and spotting, oxidative yellowing, fragrance deterioration, loss of active ingredients, and preservative system fluctuations.
Chelating agent selection should be evaluated around six questions:
① Which type of metal ion mainly needs to be controlled?
② Is the formulation pH suitable for the chelating agent to function effectively?
③ Does the formulation contain enzymes, fragrances, colorants, preservatives, oxidants, or high levels of electrolytes?
④ Does the product require green, natural, EDTA-free, low-phosphorus, or biodegradable positioning?
⑤ When achieving the same effect, which chelating agent requires a lower actual dosage and results in a more reasonable cost in the finished product?
⑥ In real formulation testing, which solution can achieve more stable performance at a lower overall cost?
For mature and cost-sensitive formulations, EDTA still has clear practical value. For green cleaning and sustainability-positioned products, MGDA, GLDA, and sodium gluconate are more worth evaluating. For natural or EDTA-free skin care and hair care products, sodium phytate, GLDA, and citrates can be prioritized. For highly alkaline systems, scale-inhibition needs, and bleaching stabilization systems, HEDP, MGDA, and sodium gluconate offer greater application value.
6. Representative Product Classification Table for Chelating Agents and Metal Ion Control in Daily Chemical Formulations
Table 1. Aminocarboxylate Chelating Agents
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
GLDA series biodegradable aminocarboxylate chelating agent | 51981-21-6 | Tetrasodium N,N-bis(carboxymethyl)-L-glutamate | Active content ≥47% | Used for calcium and magnesium ion control, stability studies of liquid cleaners, and screening of EDTA-free formulations | |
MGDA series biodegradable aminocarboxylate chelating agent | 164462-16-2 | Trisodium N-(1-carboxyethyl)iminodiacetate | ≥95% (T) | Used for cleaning performance evaluation under hard-water conditions, detergent formulation screening, and calcium/magnesium ion control experiments | |
EDDS series biodegradable aminocarboxylate chelating agent | 20846-91-7 | N,N'-Ethylenediaminedisuccinic acid (EDDS) | ≥98% | Used for biodegradable chelating agent research, metal ion spiking stability tests, and green cleaning formulation screening | |
IDS series biodegradable aminocarboxylate chelating agent | 144538-83-0 | Tetrasodium iminodisuccinate | AR | Used for hard-water compatibility testing, EDTA-free cleaning formulation research, and calcium/magnesium ion chelation evaluation | |
EDTA series aminocarboxylate chelating agent | 60-00-4 | Ethylenediaminetetraacetic acid | Ultrapure grade, anhydrous grade, ≥99.5% (T) | Used for metal ion chelation research, calcium/magnesium/iron/copper ion control experiments, and comparative formulation stability testing | |
EDTA series aminocarboxylate chelating agent | 6381-92-6 | Ethylenediaminetetraacetic acid disodium salt dihydrate | UltraBio™, ultrapure grade, ≥98.5% | Used for metal ion control in hair care, skin care, and cleansing systems, auxiliary stabilization of preservative systems, and metal ion spiking experiments | |
EDTA series aminocarboxylate chelating agent | 139-33-3 | Disodium ethylenediaminetetraacetate | ≥99% | Used for metal ion control in daily chemical formulations, stability testing of transparent systems, and auxiliary stabilization studies of preservative systems | |
EDTA series aminocarboxylate chelating agent | 150-38-9 | Trisodium ethylenediaminetetraacetate | ≥98% | Used for metal ion control in neutral to weakly alkaline formulations, hard-water stability evaluation, and comparative testing of cleaning systems | |
DTPA series aminocarboxylate chelating agent | 67-43-6 | Diethylenetriaminepentaacetic acid (DTPA) | AR, ≥99% (T) | Used for transition metal ion chelation research, bleaching system stability testing, and yellowing/off-odor suppression experiments | |
DTPA series aminocarboxylate chelating agent | 140-01-2 | Pentasodium diethylenetriaminepentaacetate | ca. 50% in water | Used for iron and copper ion control, stability studies of oxidation-sensitive systems, and evaluation of metal ion interference in peroxide systems | |
NTA series aminocarboxylate chelating agent | 139-13-9 | Nitrilotriacetic acid | UltraBio™, ≥99% (T) | Used for chelation performance studies in professional cleaning systems, comparative hard-water control experiments, and evaluation of metal ion binding ability | |
NTA series aminocarboxylate chelating agent | 5064-31-3 | Nitrilotriacetic acid sodium salt (NTA) | ≥99% | Used for chelation experiments related to professional cleaning and water treatment, and comparative studies of calcium/magnesium ion control |
Table 2. Hydroxycarboxylic Acid, Polyhydroxy Carboxylic Acid, and Naturally Derived Chelating Agents
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Citric acid auxiliary chelating agent / acidity regulator | 77-92-9 | Citric acid, anhydrous | AR, ≥99.5% (T) | Used in mildly acidic cleaning systems, descaling formulations, auxiliary metal ion chelation, and buffering experiments | |
Citric acid auxiliary chelating agent / acidity regulator | 5949-29-1 | Citric acid monohydrate | Reagent grade, ≥98% (GC/T) | Used for acid-base adjustment, buffer system construction, mildly acidic hair care and cleansing formulations, and descaling formulation experiments | |
Citrate auxiliary chelating agent / buffer | 68-04-2 | Trisodium citrate | Anhydrous grade, USP | Used for weak chelation, buffering, and formulation pH adjustment; suitable for auxiliary stabilization in hair care, cleansing, and cleaning systems | |
Citrate auxiliary chelating agent / buffer | 6132-04-3 | Sodium citrate dihydrate | AR, ≥99% | Used for buffer systems, mild hard-water control, and stability testing of hair care, cleansing, and cleaning products | |
Gluconic acid polyhydroxy carboxylic acid chelating agent | 526-95-4 | D-Gluconic acid solution | 49–53 wt. % in H₂O | Used for preparation of gluconate systems, metal ion control research, and mild cleaning formulation experiments | |
Gluconate polyhydroxy carboxylate chelating agent | 527-07-1 | Sodium gluconate | Suitable for synthesis | Used for metal ion control in alkaline cleaning systems, dispersion stabilization, and hard-surface cleaning formulation research | |
Glucoheptonate polyhydroxy carboxylate chelating agent | 31138-65-5 | Sodium glucoheptonate dihydrate | ≥98% (T) | Used in alkaline cleaning and metal cleaning systems, calcium/magnesium ion control, and dispersion stability experiments | |
Phytic acid naturally derived chelating agent | 83-86-3 | Phytic acid solution | 70% in H₂O | Used for multivalent metal ion binding and stability studies of EDTA-free hair care, cleansing, and skin care formulations | |
Phytate naturally derived chelating agent | 14306-25-3 | Phytic acid sodium salt hydrate | ≥75% | Used in EDTA-free formulations, color stability studies, and auxiliary stabilization tests for preservative systems |
Table 3. Phosphonate Metal Ion Control Agents and Scale Inhibitors
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
HEDP series phosphonic acid scale inhibitor / metal ion control agent | 2809-21-4 | 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) | Moligand™, 60% aqueous solution | Used for scale inhibition, metal ion control, peroxide stabilization, and research on highly alkaline cleaning systems | |
HEDP series phosphonate scale inhibitor / metal ion control agent | 7414-83-7 | Disodium etidronate | ≥98% | Used for scale inhibition, metal ion sequestration, peroxide stabilization, and comparative experiments in highly alkaline systems | |
HEDP series phosphonate scale inhibitor / metal ion control agent | 3794-83-0 | Tetrasodium hydroxyethylidene diphosphonate (HEDP·Na₄) | ≥80% | Used for highly alkaline cleaning, automatic dishwashing, scale inhibition and dispersion, and metal ion control testing | |
ATMP series aminophosphonic acid metal ion control agent | 6419-19-8 | Nitrilotris(methylenephosphonic acid) solution | 50 wt. % in H₂O | Used for scale inhibition, corrosion inhibition, calcium/magnesium ion control, and professional cleaning formulation experiments | |
ATMP series aminophosphonate metal ion control agent | 20592-85-2 | Sodium aminotris(methylenephosphonate) | ≥98% | Used for scale inhibition, calcium/magnesium ion control, and studies of metal ion interference in cleaning agent systems | |
ATMP series aminophosphonate metal ion control agent | 2235-43-0 | Pentasodium aminotris(methylenephosphonate), ATMP·Na₅ | ≥28% (based on ATMP) | Used for water softening, scale inhibition, calcium/magnesium ion control, and cleaning agent stability studies | |
PBTC series phosphonocarboxylic acid scale inhibitor | 37971-36-1 | 2-Phosphonobutane-1,2,4-tricarboxylic acid | 50% in water | Used for scale inhibition under high-hardness water conditions, dispersion, and hard-surface cleaning stability studies | |
DTPMP series polyphosphonic acid metal ion control agent | 15827-60-8 | Diethylenetriaminepentakis(methylenephosphonic acid) (DTPMP) | 50% in water | Used for iron and copper ion control, peroxide system stabilization, professional cleaning, and water treatment-related experiments | |
DTPMP series polyphosphonate metal ion control agent | 22042-96-2 | (((Phosphonomethyl)imino)bis((ethylenenitrilo)bis(methylene)))tetrakisphosphonic acid, sodium salt | — | Used for research on polyphosphonate systems, metal ion sequestration, scale inhibition, and peroxide stabilization experiments |
Table 4. Inorganic Phosphate Water Softeners and Polymeric Dispersing Scale Inhibitors
Category | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Polyacrylic acid polycarboxylate dispersing scale inhibitor | 9003-01-4 | Polyacrylic acid (PAA) | Viscosity ≤2000 cP (25 °C) | Used for calcium carbonate dispersion, scale inhibition, soil anti-redeposition control, and cleaning system stability studies | |
Polyacrylate polycarboxylate dispersing scale inhibitor | 9003-04-7 | Sodium polyacrylate (PAAS) | Average Mw ~8000, 45% in H₂O | Used for inorganic particle dispersion, scale inhibition, hard-surface cleaning, and deposition control in detergent systems | |
Tripolyphosphate inorganic water softener / builder | 7758-29-4 | Sodium tripolyphosphate | Industrial grade, ≥85% | Used for calcium/magnesium ion sequestration, detergency building, dispersion, powder detergent, and heavy-duty cleaning formulation research | |
Pyrophosphate inorganic water softener / builder | 7722-88-5 | Sodium pyrophosphate | AR, ≥99% | Used for water softening, metal ion control, alkaline cleaning, and inorganic builder system experiments | |
Pyrophosphate inorganic water softener / builder | 7320-34-5 | Potassium pyrophosphate (TKPP) | AR, ≥98% | Used for liquid alkaline cleaning, calcium/magnesium ion control, dispersion, and detergency-building performance studies | |
Hexametaphosphate inorganic metal ion sequestrant / dispersant | 10124-56-8 | Sodium hexametaphosphate (SHMP) | AR | Used for metal ion sequestration, dispersion, scale inhibition, hard-water compatibility, and cleaning system stability testing | |
Tripolyphosphate inorganic water softener / builder | 13845-36-8 | Potassium tripolyphosphate | ≥85% | Used for water softening in liquid cleaning systems, dispersion, alkaline detergency building, and performance evaluation under hard-water conditions |
Note: The above are representative Aladdin products for research and formulation studies. Specific specifications, grades, COA, SDS, and applicability should be confirmed on the official website. NTA and its salts are not recommended as routine options for personal care, cosmetics, or ordinary consumer daily chemical formulations. Actual use should be confirmed based on the target formulation, safety assessment, and target-market regulations.
References
[1] Cosmetic Ingredient Review Expert Panel. Safety Assessment of EDTA & Salts as Used in Cosmetics.
[2] CosmeticsInfo.org. Disodium EDTA: Functions and Safety Information.
[3] BASF Care Chemicals. Enhancing Cleaning Performance: A Deep Dive into Chelating Agents.
[4] Nouryon. Dissolvine® Chelates Product Guide: Home Care and Personal Care Applications.
[5] Pinto I. S. S., Neto I. F. F., Soares H. M. V. M. Biodegradable Chelating Agents for Industrial, Domestic, and Agricultural Applications—a Review. Environmental Science and Pollution Research, 2014.
[6] PubChem. Ethylenediaminetetraacetic Acid; Sodium Gluconate; Tetrasodium Glutamate Diacetate Compound Records.
[7] U.S. Environmental Protection Agency. Supporting Information for Low-Priority Substance: D-Gluconic Acid, Sodium Salt.
[8] CosmeticsInfo.org. Citric Acid-Derived Ingredients.
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