Solubility: very soluble in water very soluble in water 熔点: 194-199℃ 196℃-197℃ Melting point 含量: 100±2% 99.46% Assay: 灼烧残渣: ≤0.5% 0.04% Rusidue on ignition: 铵离子: ≤0.5% <0.11% NH4+ 重金属: ≤20ppm <10ppm Heavy metals: 砷: ≤2ppm < 0.1ppm Arsenic: PH值: 2.0 ~2.5 2.2 PH: