Item Standard Analysis result Appearance white crystal or crystalline powder white crystal or crystalline powder Purity, % 99.6 Min 99.79 Loss weight on drying, % 0.3 Max 0.070 Residue on ignition, % 0.01 Max 0.001 Heavy metal (Pb), microgram/g 10 Max 0.4 Fe, microgram/g 5 Max 0.230 Cu, microgram/g 1 Max 0.065 Mn, microgram/g 1 Max 0.070 As, microgram/g 4 Max 2 Sulfate, microgram/g 30 Max 0.7 Chloride, microgram/g 10 Max 1.3 Melting point, centigrade 165~168 166.5 Color, APHA 5 Max 2.5 Clarity (5% water solution) Cloudless Cloudless Clarity (20% DMSO) Cloudless Cloudless