品级Grade                               分析纯 (AR)
干燥损失loss on ignition           ≤20%
水溶性solubility H2O:               soluble0.1 g/mL, clear, colorless
氯chloride (Cl-):                       ≤200 ppm
硫酸根sulfate (SO42-):            ≤100 ppm
  Ca:                                       ≤200 ppm
  Cd:                                       ≤50 ppm
  Co:                                       ≤50 ppm
  Cu:                                       ≤50 ppm
  Fe:                                       ≤50 ppm
  K:                                         ≤200 ppm
  Na:                                      ≤3000 ppm
  Ni:                                       ≤50 ppm
  Pb:                                      ≤50 ppm
  Zn:                                      ≤50 ppm

≥99.9% metals basis：

外观Appearance                                     白色粉末或结晶
红外光谱鉴别Infrared spectrometry       Conforms to Structure
W                                                          67.5% - 70.0%  (Gravimetric Analysis)
纯度Purity                                             ≥99.9% Based On Trace Metals Analysis
ICP:                                                      Confirms Si and W Components Confirmed
痕量金属分析Trace Metal Analysis         ≤1000ppm by ICP Atomic emission
(As、Ba、Ca、Co、Cr、Cu、Fe、Mg、Na、Ni、Pb、Sb、Sn、Ti、V)