质量标准
外观appearance white crystalline powder
水溶性solubility clear colorless solution at 10g plus 30ml of water
纯度Purity by sulfuric acid titration ≥99%
水分Water by Karl Fischer ≤1%
紫外吸收uv absorbance ≤0.1 at 290nm (25%w/w)
重金属heavy metals (aslead) ≤5 ppm
purity by sulfuric acid titration nlt 99% (corrected for water content)