Used as a determination of iron, mercury, and silver.Heavy Metals:≤ 0.001% (as Pb)Chloride (Cl-):≤ 0.01%Sulfate (SO42-):≤ 0.01%Iron (Fe):≤ 0.0002%Water (Karl Fisher):≤1.8%pH:4.5-6.0 (5% solution at 25°C)Residue On Ignition:≤0.06%Storage:Powder may be stored at RT. Stable for 6 months.