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Sodium PCA – Powerful Humectant for Cosmetics and Personal Care

 

Sodium Pyrrolidone Carboxylate (Na-PCA): Properties and Applications

1. Introduction

Sodium pyrrolidone carboxylate (Sodium PCA, Na-PCA) is the sodium salt of pyroglutamic acid (5-oxoproline). It is one of the most effective humectants used in cosmetic and personal care formulations, known for its excellent water-binding properties and high biocompatibility. Sodium PCA is a key component of the skin's Natural Moisturizing Factor (NMF), which maintains the hydration balance of the stratum corneum. Its ability to attract and retain moisture makes it a valuable ingredient in skin care, hair care, and personal care products.

2. Chemical Structure and Properties

Chemical name: Sodium 5-oxo-L-prolinate; Sodium pyrrolidone carboxylate

Molecular formula: C₅H₆NNaO₃

Molecular weight: 151.10 g/mol

CAS number: 28874-51-3

EC number: 249-277-1

Appearance: White to off-white crystalline powder or clear, colorless to slightly yellowish liquid (typically 50% aqueous solution)

Solubility: Highly soluble in water and alcohols

pH (1% aqueous solution): 6.5–8.5

3. Mechanism of Action

Sodium PCA acts as a powerful humectant, attracting and binding water molecules to the skin and hair surface. As a component of the NMF, it helps maintain the hydration of the stratum corneum by reducing transepidermal water loss (TEWL). Its low molecular weight allows it to penetrate the upper layers of the epidermis, where it provides long-lasting moisturization. Sodium PCA also helps to improve skin elasticity, reduce flaking, and enhance the overall barrier function of the skin.

4. Applications

Skin care: Used in creams, lotions, serums, moisturizers, and facial toners to provide deep hydration, improve skin texture, and enhance elasticity. Typical usage levels: 0.5–2.0%.

Hair care: Added to shampoos, conditioners, and hair masks to retain moisture, reduce brittleness, improve combability, and enhance shine.

Personal care: Used in body washes, shower gels, and hand soaps to provide moisturizing benefits.

Color cosmetics: Incorporated into foundations, lipsticks, and concealers to improve spreadability and prevent drying.

Men's grooming: Used in after-shave products to soothe irritation and restore skin hydration.

Baby care: Suitable for gentle, sensitive skin formulations.

5. Safety and Toxicology

Skin and eye irritation: Sodium PCA is considered non-irritating and non-sensitizing at recommended concentrations.

Oral toxicity: Low acute oral toxicity.

Regulatory status: Approved for use in cosmetics without special restrictions in most countries (EU, US, Japan, and others).

Environmental profile: Readily biodegradable and derived from natural amino acids; environmentally friendly.

6. Advantages and Limitations

Advantages:

  • Excellent water-binding and humectant properties.

  • Natural component of skin's NMF – highly biocompatible.

  • Low irritation potential – suitable for sensitive skin.

  • Compatible with a wide range of cosmetic ingredients.

  • Readily biodegradable and environmentally friendly.

  • Effective at low concentrations (0.5–2.0%).

  • Improves skin elasticity and reduces flaking.

Limitations:

  • May be less effective in very low-humidity environments.

  • Can be hygroscopic; requires proper storage and formulation.

7. Conclusion

Sodium PCA (CAS 28874-51-3) is a highly effective and widely used humectant in the cosmetic and personal care industries. Its ability to attract and retain moisture, combined with its natural occurrence in the skin's NMF, makes it a valuable ingredient for improving skin hydration, elasticity, and barrier function. With a favorable safety profile, biodegradability, and compatibility with a wide range of formulations, Sodium PCA is a versatile and sustainable choice for moisturizing skin care, hair care, and personal care products.

 

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