8-Hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt [HPTS] *CAS 6358-69-6* - 1 g

8-Hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt [HPTS] is the cell-impermeable fluorescent pH indicator used for slightly acidic pH range (pKa = 6.4).