Assay(by Argentometry) min 99.0% 5 kgSulphate(SO4) max 0.015%Heavy metals(as Pb) max 0.001%Arsenic(As) max 0.0003%Lead(Pb) max 0.001%Calcium(Ca) max 0.02%Iron(Fe) max 0.002%Copper(Cu) max 0.0025%Zinc(Zn) max 0.0025%Residue on ignition(800oC) max 0.1%Iodide, Bromide(I,Br) passes testpH(5% soln.) 4.5-5.5Identity passes testClarity of solution passes testAcididty or Alkalinity passes testLoss on drying (105oC) max 0.5%Thiocyanate passes