Ensulizole (INN) is a common sunscreen agent. In 1999, the United States Food and Drug Administration regulated that the name ensulizole be used on sunscreen labels in the United States. Phenylbenzimidazole sulfonic acid is primarily a UVB protecting agent providing only minimal UVA protection. The scope of UVB is 290 to 340 nanometers whereas the UVA range is 320 to 400 nanometers. For better UVA protection, it must be paired with avobenzone, titanium dioxide, or zinc oxide; outside of the United States it can also be paired with a UV absorber of the Tinosorb or Mexoryl types. Because phenylbenzimidazole sulfonic acid is water-soluble, it has the characteristic of feeling lighter on skin. As such, it is often used in sunscreen lotions or moisturizers whose aesthetic goal is a non-greasy finish. The free acid is poorly soluble in water, so it is only used as its soluble salts.

Appearance and properties: white fine crystalline powder

Density: 1.497g/cm3

Melting point: 300 °C

Flash point: >100oC

Water solubility: soluble

Stability: Stable under normal temperatures and pressures. May decompose when exposed to light.

Storage conditions: Keep container closed when not in use. Store in a tightly closed container. Store in a cool, dry,  well-ventilated area away from incompatible substances.

Usage:Used as ultraviolet absorbent, used in sunscreen skin care cosmetics.