USP, BP级ASSAY (NaH2PO4) 98.0 - 100.5% pH OF A 5% SOLUTION 4.2 - 4.5 WATER 11.5 - 14.5% INSOLUBLE SUBSTANCES -- 0.2% CHLORIDE (Cl) -- 0.014% SULFATES (SO4) -- 300 PPM Al, Ca, & RELATED ELEMENTS TO PASS TEST ARSENIC (As) -- 2 PPM HEAVY METALS (as Pb) -- 10 PPM IRON (Fe) -- 10 PPM