Characteristics   Almost white or light yellow green crystalline powder.

Fluorine assay               4.3%～5.3%

Related substance               ≤2.0%

Loss on drying                  ≤4.0%

Residue on ignition              ≤5.0%

Heavy metals                  ≤20ppm

Assay                        ≥98.0%

Standard: enterprise standard.