... Cleaners, Food & Feed industry etc. Sodium Tripolyphosphate (STPP)Synonyms: triphosphoric acid pentasodium salt, pentasodium triphosphate, tripolyphosphate pentasodium, sodium triphosphate, STPP, armofos, empiphos stp-D, freez-gard ... PURITY(As Na5P3O10):94% MIN.Total Phosphorous(as P2O5):57%MIN.Water insoluble:0.06 %MAX.Iron:0.009%MAX.PH ... retained on mesh)2%MAX.Bulk density( g/cm3 ):0.65-0.75