STTP Items IndexTech. Grade Food Grade Na5P3O10 (%) 94%Min 95%Min P2O5 (%) 57%Max 57%Max Insolubles in water (%) 0.15%Max 0.15%Max Fe (%) 0.01%Max 0.01%Max Ph (1% solution) 9.2-10 9.5-10 Heavy Metal (As Pb) (%) -- 0.001%Max Arsenic (As) (%) -- 0.0003%Max Fluoride(F) (%) -- 0.003%Max Whiteness(%) 90%Min 90%Min