DropPrev® CHA: The Next-Generation Preservative Active at Neutral pH

In the world of cosmetic preservation, formulating at higher pH levels has always been a challenge. Traditional organic acid preservatives like sorbic acid, benzoic acid, or dehydroacetic acid lose their effectiveness as pH rises above 6, leaving formulations vulnerable to microbial growth. This limitation often forces brands to compromise between stability, skin feel, and preservation efficacy.

Enter DropPrev^® CHA (Caprylhydroxamic Acid) – a innovative, multifunctional ingredient that breaks the pH barrier.

What is DropPrev^® CHA?

DropPrev^® CHA is a mild organic acid derived from caprylic acid and hydroxylamine. With the INCI name Caprylhydroxamic Acid and a molecular weight of 159.23, it’s a globally recognized and compliant material, included in China’s IECIC 2015 inventory.

But what truly sets it apart is its exceptionally high pKa of ~9.4.

The pH Game-Changer

For traditional organic acids, antimicrobial activity depends on the percentage of undissociated acid, which drops dramatically as pH increases. At pH 6, an acid needs a pKa of at least 6 to be 50% active. Most conventional preservatives fall short.

DropPrev® CHA defies this trend. Thanks to its high pKa, it remains fully active across a wide pH range.

Comparative Activity at Various pH Levels:

This means CHA is the only organic acid that remains completely undissociated and active at neutral pH.

Dual Mode of Action

1. Metal Chelation – Primary Mechanism

• CHA acts as a potent chelator, particularly for Fe³⁺ (stability constant: 11.4), competing with microbial siderophores for iron.

• Iron is essential for microbial growth, electron transport, and DNA synthesis. By sequestering iron, CHA starves microbes of this vital nutrient.

• It also chelates Ca²⁺ and Mg²⁺ at the cell membrane, increasing permeability and disrupting microbial integrity.

2. Classic Organic Acid Activity

• In its undissociated form, CHA exhibits lipophilic properties, allowing it to penetrate microbial cell membranes.

• Once inside, it can disrupt internal pH and metabolic processes.

Key Benefits & Features

• Broad-Spectrum Activity: Effective against bacteria, yeast, and mold. Shown to inhibit Aspergillus niger at a low MIC of 0.078%.

• Formulation Flexibility: Compatible with emulsions, anhydrous systems, surfactant-based cleansers, and color cosmetics.

• Similar Log Kow (1.67) to other common preservatives like caprylyl glycol and glyceryl caprylate, indicating favorable skin feel and solubility.

• High Safety Profile: Widely studied, non-mutagenic (AMES test negative), and historically used as a feed additive.

Recommended Use

• Usage Level: 0.05% – 0.15%

• Solubility: Soluble in propylene glycol, glycerin, and surfactants.

• pH Range: Effective from pH 2–8 (activity gradually decreases above pH 8).

• Application: Best paired with bacterial and yeast inhibitors (e.g., phenoxyethanol, ethylhexylglycerin, 1,2-octanediol) for broad-spectrum protection.

• Note: Avoid extended heating above 90°C. Add EDTA-2Na to prevent discoloration from iron-containing clays or minerals.

Conclusion

DropPrev^® CHA represents a significant step forward in preservation technology. Its ability to remain active at neutral pH, combined with its dual-action mechanism and strong safety record, makes it an ideal choice for modern, mild, and high-performance cosmetic formulations.

Whether you're developing a gentle facial cream, a pH-balanced shampoo, or a long-wearing makeup product, CHA offers reliable preservation without compromising pH or sensory attributes.