CAS 77643-91-5 appears in our catalog under these names: Sulfamethazine-13C6, 98% +98%atom%13C, Sulfamethazine 13C6 (phenyl 13C6), Sulfamethazine-13C6, >95% (HPLC), Sulfamethazine–13C6, Sulfamethazine-13C6, 99.10%. Offered by: AmBeed, Dr. Ehrenstorfer, TRC, GLPBio, MedChemExpress. Available pack sizes: 1mg, 10mg, 5mg, 1 mg, 1x1ml, 1x10mg.