- Synonyms: Natural Red 28 - CAS [1400-62-0] - EINECS-No.: 215-750-6 - Solub. in water: (25 ºC): almost insoluble - Tariff number: 3203 00 19 00 - Applications: microscopy, dye (for biology). SPECIFICATIONS mol/l) : 575 - 580 nm Absorptivity (A1%/1 cm; l max.): 600 - 800