... crystalWhite crystalWhite crystalPurity, %98.5 min99.0 min99.5 minMoisture, %1.0 max1.0 max0.5 maxChloride (Cl), %1.0 ... 05 max0.02 max0.01 maxpH (5% solution)6.0-8.06.0-8.06.0-8.0Arsenic (As), mg/kg-10 ... max0.2 maxLead (Pb), mg/kg-10 max0.2 maxIron (Fe), mg/kg--0.5 ... maxCopper (Cu), mg/kg--0.5 maxUse: sensitive materials, sensitive photographic film, ...