- Synonyms: 3',3''-Dibromothymol-sulfonphthalein, BTB - C27H28Br2O5S - M = 624,40 g/mol - CAS [76-59-5] - EINECS-No.: 200-971-2 - Solub. in water: (20 ºC): insoluble - Tariff number: 2934 99 90 90 - Applications: analytical chemistry, indicator. SPECIFICATIONS pH range (yellow to blue): 5,8 - 7,6 Absorption maximum l1 (pH 5,8) : 430 - 435 nm Absorption maximum l2 (pH 7,6) : 615 - 618 nm Absorptivity (A1%/1 cm; l1; pH 5,8 on dried sample): 260 - 300 Absorptivity (A1%/1 cm; l2; pH 7,6 on dried sample): 470 - 520 transition range acc. ACS : passes test loss on drying (110 ºC): max. 3 %