... I 5-40, Fe max 70PPM Sodium Tripolyphosphate (STPP)Synonyms: triphosphoric acid pentasodium salt, pentasodium triphosphate, tripolyphosphate pentasodium, sodium triphosphate, STPP, armofos, empiphos stp ... (G/CM3)0.35-0.90.8PHASE L10-3026.3 Sodium Tripolyphosphate