znso4 solubility 1,high Zinc content with low heavy metal 2,free sample 3,SGS,BV,CIQ inspection welcoming Specificationszinc ... sulfate solubility 1,high Zinc content with low heavy metal 2,free sample 3,SGS,BV,CIQ inspection welcomingzinc sulfate ... ), %≥35.522.533.5%Water Insoluble , %≤0.050.050.05Heavy Metal (Pb), %≤0.0010.0010.001Arsenic (As), %≤0.00050.00050.0005Cadmium ...