... grade Main content, %; 94.0 P2O5%≥ 57.0 Water insoluble %; 0.1 Iron, as Fe %; 0.015 pH of 1% ... grade Main content, %: 94.0 P2O5%; 57.0 Water insoluble %; 0.05 Iron, as Fe %; 0.01 pH of 1% water ... solution 9.5-10.0 Heavy metal, as Pb %; 0 ... .001 Arsenic, as As, %; 0 ...