K2SO4 M.W. 174.27  Assay(acidimetric) 99.0-101.0% pH(5% solution) 5.5-8.5 Idenditiy passes test Appearane of solution passes test Acidity or alkalinity passes test Chloride(Cl) max 0.004% Heavy metals(as Pb) max 0.001% Iron(Fe) max 0.001% Arsenic(As) max 0.0002% Magnesium(Mg) max 0.002% Calcium(Ca) max 0.02% Sodium(Na) max 0.05% Loss on drying (1050C) max 1.0%