外观Appearance                           White Crystalline Powder
纯度Purity(Titration by NAOH)            ≥99.5 %
Anhydrous
水分Water (by Karl Fischer)              ≤5%
灼烧残渣ign. residue (900 °C)            ≤0.05% (as SO4)
pH                                        2.5-4.0 (25 °C, 0.5 M in H2O)
useful pH range                           5.5 - 6.7
pKa (25 °C)                              6.1
水溶性solubility H2O:                     soluble0.5 M at 20 °C, clear, colorless
氯chloride (Cl-):                         ≤50 ppm
硫酸根sulfate (SO42-):                    ≤50 ppm
cation traces
  Al:                                     ≤5 ppm
  As:                                     ≤0.1 ppm
  Ba:                                     ≤5 ppm
  Bi:                                     ≤5 ppm
  Ca:                                     ≤20 ppm
  Cd:                                     ≤5 ppm
  Co:                                     ≤5 ppm
  Cr:                                     ≤5 ppm
  Cu:                                     ≤5 ppm
  Fe:                                     ≤5 ppm
  K:                                     ≤50 ppm
  Li:                                     ≤5 ppm
  Mg:                                     ≤5 ppm
  Mn:                                     ≤5 ppm
  Mo:                                     ≤5 ppm
  Na:                                     ≤50 ppm
  Ni:                                     ≤5 ppm
  Pb:                                     ≤5 ppm
  Sr:                                     ≤5 ppm
  Zn:                                     ≤5 ppm
λ                                    0.5 M in H2O
UV absorption λ: 260 nm A:                ≤0.025
  λ: 280 nm A:                            ≤0.020