Orange II sodium salt (C.I. 15510)

Indicator pH 7,4-8,6 and pH 10,2-11,8
Acid orange 7

Empirical formula C₁₆H₁₁N₂NaO₄S 
Molar mass (M) 350,33 g/mol
Melting point (mp)>300 °C
WGK 3
CAS No.[633-96-5]
EG-Nr. 211-199-0

Water-soluble dye, is used in cytology, e.g. as ingredient of Papanicolaou solution 2b.