A fluorescent whitening agent used for household goods. The structure of a photodegradation product of 4,4'-Bis(2-sulfostyryl)biphenyl Na salt was determined to be 4-(4-Formylphenyl)stilbene-2'-sulfonic acid, which was biodegradable.Form:Greenish Yellow SolidMelting Point:>300°C (dec.)Solubility:DMSO, Water