纯度Purity 97.5 - 102.5 % (Iodometry) 碱度Alkalinity 1.5 - 2.5 % (以 Na2CO3计) pH 9.5 - 10.5 (10% 溶液) 痕量分析Trace analysis :铁Fe < 10 ppm 锌Zn < 30 ppm 硫化钠Na2S < 25 ppm 亚硫酸钠sodium sulfite: < 6.0% 羟甲基磺酸钠sodium hydroxymethane sulfonate: < 6.0%