- Synonyms: 2-Hydroxy-1-(2-hydroxy-4-sulpho-1-naphthylazo)-3-naphthoic acidr- C21H14N2O7Sr- M = 438,42 g/molr- CAS [3737-95-9]r- EINECS-No.: 223-117-0r- Solub. in water: (20 ºC): insolubler- Melting point: 300 ºCr- Tariff number: 2927 00 00 90r- Applications: analytical chemistry, indicator, for the identification of: calcium.rrSPECIFICATIONSrAbsorption maximum l (in ethanol) : 569 - 572 nm rAbsorptivity (A1%/1 cm; l1; pH 3,0 on dried sample): min. 250 rwater (K.F.): max. 10 %rsuitability as indicator for metal titration : passes testr