Sinosorb UV-284 (BP-4 / Benzophenone-4) is a highly efficient broad-spectrum, water-soluble UV absorber that provides strong, simultaneous protection against both UVA (280–320 nm) and UVB (320–360 nm) radiation. Because of its sulfonic acid group, it is readily soluble in water and polar organic solvents without co-solvents, offering excellent photostability, thermal stability, and light stabilization in aqueous formulations.