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BENZOPHENONE-5.

Valuable CAS 6628-37-1 / LIGHT STABILIZER, UV ABSORBER, UV FILTER

A specialized water-soluble sodium salt that serves as both a broad-spectrum UV filter and a high-performance formulation stabilizer. It is designed to maintain the integrity of cosmetic actives while providing secondary protection against the damaging effects of UVA and UVB radiation.

UV Filter Light Stabilizer Sunscreen Active

Science

As a broadband organic filter (UV-BB), it absorbs ultraviolet radiation within the 280–400 nm range. It converts high-energy photons into low-energy heat through electronic excitation and relaxation. Simultaneously, it acts as a photostabilizer, preventing the degradation of colors, fragrances, and sensitive active molecules caused by light exposure.


Research

High confidence
Effective range 0.1–5%
Optimal

5%

Key findings

  1. 01 In vitro testing at a 5% concentration demonstrated SPF efficacy statistically equivalent to high-load botanical extract formulations.
  2. 02 Regulatory safety assessments (SCCS 2025) confirmed its safety as a UV filter in leave-on products up to a 5% threshold.

Transparency

Not commonly dusted
Min. effective
0.5%
Red flag below
0.1%

When used solely as a light stabilizer to protect product color or scent, concentrations below 0.5% are standard. However, to claim meaningful photoprotective benefits for the skin, it must be formulated near its regulated 5% maximum.


The Formula

Solubility
Water
Optimal pH 6 – 7.5
0 7 14

Stability

Benzophenone-5 is highly hygroscopic; moisture control during manufacturing is critical. It is the salt form of sulisobenzone, which allows for better integration into near-neutral aqueous systems compared to its acidic parent form.

Synergies

  • Water-soluble antioxidants
  • Chelating agents

Conflicts

  • Strong oxidizing agents
  • Highly alkaline environments (pH > 7.5 can shift UV absorption peaks)

Safety

CIR Status
Safe as used
Max tested
5%
Sensitization risk Low

Regulated in the EU at a maximum of 5% (calculated as acid). While safe for the general population, its chemical class is sometimes monitored for potential endocrine concerns, though current data supports its safety at authorized levels.


Your Skin

Yes Normal
Yes Dry
Yes Oily
No Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Valuable

An essential secondary filter and stabilizer that excels in protecting both the skin and the formula's active potency from light-induced degradation.


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