5-Sulfosalicylic Acid, Dihydrate, Crystal, Reagent, ACS, also known simply as sulfosalicyclic acid, is used to determine urine protein content. As an ACS grade quality reagent, its chemical specifications are the de facto standards for chemicals used in many high-purity applications and typically designate the highest quality chemical available for laboratory use. Spectrum Chemical manufactured Reagent ACS grade products meet the toughest regulatory standards for quality and purity. Synonyms: 2-Hydroxy-5-sulfobenzoic Acid