What Is Triethanolamine?
Triethanolamine (TEA) is a multifunctional organic compound belonging to the class of amino alcohols. Its chemical formula is N(CH₂CH₂OH)₃, meaning it contains both amine and hydroxyl functional groups — a combination that makes it uniquely useful as a pH adjuster, emulsifier, and surfactant across a wide range of industries.
TEA is a clear to pale yellow, viscous liquid with a mild ammonia-like odor. It is water-soluble, hygroscopic, and miscible with many common solvents. At room temperature it is liquid, with a melting point around 20–21°C (68–70°F).
Key Properties
| Property | Value |
|---|---|
| Chemical formula | C₆H₁₅NO₃ |
| Molecular weight | 149.19 g/mol |
| Appearance | Clear to pale yellow viscous liquid |
| pH (neat) | ~10.5 (strongly alkaline) |
| Solubility | Miscible with water and ethanol |
| Boiling point | 335°C (635°F) |
| Flash point | 179°C (354°F) |
Primary Uses of Triethanolamine
1. pH Adjuster in Cosmetics and Personal Care
The most common cosmetic use of TEA is as a pH neutralizer and buffer. It is highly alkaline (pH ~10.5), so small amounts are added to formulations to raise pH and bring acidic systems into the desired range (typically pH 5–7 for skincare).
It is especially useful for neutralizing carbomer and carbopol gels — when TEA is added to a carbomer dispersion, it neutralizes the polymer, causing it to swell and form a clear, stable gel. This technique is widely used in:
- Moisturizing gels and creams
- Hair styling gels
- Sunscreen formulations
- Topical pharmaceutical gels
Typical usage rate for pH adjustment: 0.1–1.0% (use sparingly — a little goes a long way)
2. Emulsifier and Soap Formation
TEA reacts with fatty acids to form triethanolamine soaps (TEA salts), which function as anionic surfactants and emulsifiers. This reaction is the basis for many O/W (oil-in-water) emulsions in cosmetics. TEA-based emulsifiers are found in:
- Cold creams and cleansing lotions
- Makeup removers
- Sunscreen emulsions
- Hair conditioners
3. Surfactant and Wetting Agent
TEA lowers surface tension, improving wetting, spreading, and foam formation in liquid formulations. It enhances the performance of other surfactants in shampoos, liquid soaps, and cleaning products.
4. Industrial and Metalworking Applications
Outside of cosmetics, TEA has important industrial uses:
- Metalworking fluids: Used as a corrosion inhibitor and pH buffer in cutting oils and coolants.
- Cement and concrete: Added as a grinding aid and early-strength accelerator.
- Textile processing: Used in softening agents and dye-leveling formulations.
- Agricultural chemicals: Serves as an emulsifier and pH modifier in herbicide and pesticide formulations.
- Gas purification: Used to scrub CO₂ and H₂S from natural gas streams.
5. Pharmaceutical Applications
In pharmaceutical manufacturing, TEA is used as:
- A pH adjuster in topical creams, gels, and ointments
- An emulsifying agent in emollient formulations
- A solubilizer for poorly water-soluble active ingredients
Safety and Regulatory Considerations
TEA is approved for use in cosmetics by the FDA and is assessed by the Cosmetic Ingredient Review (CIR) as safe at concentrations up to 5% in rinse-off products and up to 2.5% in leave-on products, provided the formulation is not intended for prolonged contact with skin or use on damaged skin.
Key safety notes:
- Avoid formulations where TEA could react with nitrosating agents, which can form potentially harmful nitrosamines.
- Not recommended for use around the eyes at high concentrations.
- At high concentrations, TEA can cause skin irritation — always use at recommended levels.
- Industrial-grade TEA should never be used in cosmetic or pharmaceutical applications; always use cosmetic- or pharmaceutical-grade material.
Grades and Purity
Triethanolamine is available in several grades:
- 99% (Anhydrous): Highest purity, preferred for cosmetic and pharmaceutical use.
- 85%: An aqueous solution; commonly used in industrial applications and some cosmetic formulations.
- Industrial grade: Lower purity; not suitable for skin-contact or ingested applications.
Always request a Certificate of Analysis (COA) from your supplier specifying purity, color (APHA), specific gravity, and water content. Learn what to look for in a COA in our guide: How to Read a Certificate of Analysis for Food-Grade Ingredients (coming soon).
Formulation Tips
- Add TEA slowly to the formulation while mixing and monitoring pH — overshoot is easy given its high alkalinity.
- For carbomer neutralization, target a final formulation pH of 6.0–7.0 for skin products.
- TEA is heat-stable and can be added to either the water or cool-down phase of an emulsion.
- Store in tightly sealed containers away from heat, light, and air to prevent discoloration and oxidation.
Storage and Handling
- Store at room temperature (15–25°C); TEA may partially solidify below its melting point (~20°C) — warm gently to reliquefy.
- Keep containers sealed to prevent CO₂ absorption from air, which can affect pH and performance.
- Use appropriate PPE (gloves, eye protection) when handling undiluted TEA due to its alkalinity.
- Shelf life: typically 24 months when stored properly in sealed containers.
Related Ingredients
When evaluating TEA, formulators often compare it to related amino alcohols:
- Diethanolamine (DEA): Similar function but with greater regulatory restrictions due to nitrosamine concerns; TEA is generally preferred.
- Aminomethyl propanol (AMP): An alternative pH adjuster with a lower nitrosamine formation risk; sometimes substituted for TEA in leave-on products.
- Sodium hydroxide (NaOH): A stronger base used for pH adjustment; does not contribute emulsification functionality like TEA.