AOS 40: A Sulfate-Free Anionic Surfactant for High-Performance Cleaning and Personal Care Formulations

Alpha Olefin Sulfonate 40 (AOS 40) is an anionic surfactant produced through direct sulfonation of C14–C16 alpha olefins, followed by neutralization with caustic soda. The result is a versatile, high performing surface active agent suited to a wide range of detergent, industrial cleaning, and personal care applications.

Chemical Identity and Specifications

AOS 40 carries the INCI name Sodium C14-16 Olefin Sulfonate and CAS number 68439-57-6.

• Appearance (25°C): Clear, light-yellow liquid

• Active Matter: 38.00 – 40.00%

• Unsulfated Organic Matter: 2.50% max

• Inorganic Sulfate: 1.00% max

• Color (Klett, 5% AM soln.): 90 max

• pH (25°C, neat): 6.0 – 8.0

• Molecular Weight: ~316

Performance Characteristics

AOS 40 is valued in formulation work for a combination of properties that are difficult to achieve simultaneously in a single surfactant:

• High foaming power, making it effective in applications where foam generation and stability matter

• Strong emulsification performance across oil-water systems

• Skin mildness relative to many other anionic surfactants, supporting its use in personal care formulations

• Excellent lime soap dispersion, which helps maintain cleaning performance in hard water conditions

This profile positions AOS 40 as a practical alternative in formulations where sulfate-based surfactants such as SLS or SLES are being reconsidered.

Key Benefits

Beyond its core performance profile, AOS 40 delivers a set of practical advantages that matter to formulators and procurement teams alike:

• Hard water compatibility. Strong lime soap dispersion means consistent cleaning and foaming performance even in regions with high water hardness, reducing the need for additional water softening additives.

• Formulation cost efficiency. High foam stability and active matter concentration can allow for lower use levels relative to less concentrated or less efficient surfactants, supporting total cost of ownership goals.

• Cross-category versatility. The same product supports personal care (shampoos, hand soaps), industrial and household cleaning (dishwashing, hard surface cleaners), and oilfield chemistry (foam drilling, foam fracturing), simplifying sourcing for multi-category manufacturers.

• Mildness without compromise. Skin mildness relative to other anionic surfactants allows formulators to meet sensory and safety expectations in personal care without sacrificing cleaning or foaming power.

• Regulatory readiness. A broad set of compliance and inventory listings reduces the documentation burden for formulators selling into multiple international markets.

• Supply and process reliability. Consistent specifications (active matter, pH, color) support batch to batch reproducibility in finished formulations.

A Sulfate-Free Positioning, With a Technical Nuance

AOS 40 is marketed and classified as a sulfate free surfactant. This refers to its surfactant chemistry: it is not an alkyl sulfate, and it does not belong to the sulfate ester class of surfactants that includes SLS and SLES. Formulators moving away from sulfate based systems for marketing or sensitivity reasons can use AOS 40 as a functional substitute without sacrificing foam or cleaning performance.

It's worth noting that the finished product does contain a small proportion of sodium sulfate, as an inorganic salt that occurs as part of the manufacturing and neutralization process. This is a byproduct salt, not a sulfate based surfactant, and it does not change AOS 40's classification or its suitability for sulfate free formulation claims. The full composition breakdown is as follows:

• Sodium C14-16 Olefin Sulfonate (CAS 68439-57-6): 38.00 – 40.00%

• Tetradecene (CAS 1120-36-1) and Hexadecene (CAS 26952-14-7), combined: 0.00 – 2.50%

• Sodium Sulfate (CAS 7757-82-6): 0.00 – 1.00%

• Sodium Benzoate (CAS 532-32-1): 0.00 – 0.07%

• Water (CAS 7732-18-5): 56.43 – 62.00%

This distinction is common across the alpha olefin sulfonate category and is worth understanding when responding to formulator or customer questions.

Regulatory and Compliance Profile

AOS 40 comes with a broad set of compliance statements relevant to personal care and cosmetic formulators:

• Free of CMR category 1 or 2 substances under CLP Regulation (EC) No. 1272/2008

• Free of BHT, BHA, parabens, phthalates, PFAS, and 1,4-dioxane

• Not derived from animal sources; vegan and BSE/TSE-free

• Not irradiated during manufacture

• Compliant with the ASEAN Cosmetics Directive and free of allergens listed under EU Cosmetic Regulation 1223/2009 and EU Regulation 2023/1545

• Heavy metals (lead, arsenic, cadmium, mercury) reported as not detected via ICP-AES testing

• Listed on major chemical inventories including TSCA (USA), EINECS (Europe), DSL (Canada), AICS (Australia), and equivalent inventories in China, Japan, South Korea, Taiwan, New Zealand, and the Philippines

This profile supports formulators working across multiple regulatory jurisdictions who need documentation to accompany product claims.

Applications

AOS 40's combination of foaming, emulsification, and hard water tolerance supports use across several formulation categories:

• Shampoos and hand soaps, where mildness and foam quality are priorities

• Dishwashing formulations and industrial cleansers

• Hard surface and automotive cleaning products

• Oilfield applications, including foam drilling and foam fracturing/stimulation

Handling and Storage

AOS 40 is classified as a skin and eye irritant (Category 2 skin irritation, Category 1 serious eye damage) and should be handled with appropriate PPE, including gloves and eye protection. It should be stored in a cool, dry, well ventilated location, with container temperatures maintained above 20°C to avoid gel formation or phase separation. If the product has been stored for an extended period or at elevated temperature, it should be re-mixed and pH checked before use.

Why It Matters for Formulators

As sulfate free formulation continues to gain traction in personal care, and as cost and hard water performance remain persistent formulation challenges in industrial and household cleaning, AOS 40 offers a documented, well characterized option that addresses both. Its combination of foam performance, mildness, and broad regulatory support makes it a practical building block across multiple product categories.

For technical data sheets, safety data sheets, or formulation support for AOS 40, contact California Chemical.