C9-15 Alkyl Phosphate

What is C9-15 Alkyl Phosphate?

C9-15 Alkyl Phosphate is a synthetic anionic surfactant produced by reacting phosphoric acid with linear alcohols containing 9 to 15 carbon atoms. This creates a phosphate ester that serves as a versatile functional ingredient primarily in rinse-off cosmetics such as shampoos, body washes, facial cleansers, and some lotions. In formulations, it works by lowering surface tension at the interface of water, oil, and soil particles, which enables effective dirt and oil removal through micelle formation during rinsing. Its emulsifying action stabilizes oil-in-water mixtures, promoting uniform texture and preventing phase separation. Compared to traditional sulfates, this ingredient offers milder performance, supporting foam generation while preserving skin's moisture barrier to a greater extent. It appears in concentrations that balance efficacy and gentleness across hair and skin care products.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 1 View on EWG →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Surfactant
Lowers surface tension to enable cleansing, emulsifying, and foaming; central to shampoos, body washes, and many emulsions and micellar systems.
Cleansing agent
Removes dirt, oil, and impurities by lowering surface tension and forming micelles, enabling soils to be lifted and rinsed away from skin, hair, or teeth.
Emulsifying agent
Enables stable mixing of oil and water phases by forming an interfacial film, helping create lotions, creams, and cleansers with consistent texture.

Benefits

Gentle removal of dirt, oil, and impurities without harsh stripping.

Supports stable emulsions for smooth lotion and cleanser textures.

Promotes foaming in shampoos and washes for satisfying lather.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Individuals with normal or oily skin using daily cleansers.
Those with rare allergies to phosphate esters.
People seeking mild surfactants in shampoos or body washes.
People experiencing irritation from similar surfactants.
Users of emulsions preferring non-comedogenic ingredients.
Individuals not patch-testing new products.

Safety Notes

  • Considered low hazard in cosmetic use by safety assessments.
  • Typically mild with minimal irritation potential in rinse-off products.

Frequently Asked Questions about C9-15 Alkyl Phosphate

What does C9-15 Alkyl Phosphate do in products?

Acts as a surfactant to cleanse by lifting dirt, emulsify oils and water, and create foam.

Is it suitable for sensitive skin?

Generally mild and low irritation, but patch test as with any ingredient.

Does it clog pores?

Rated non-comedogenic, safe for acne-prone skin types.