1) Assay (on dry basis): ≥ 98.5% 2) Specific Rotation: [α]20 D:-26.0° ~ -29.0° 3) Residue on Ignition: ≤ 0.3% 4) Ammonium (NH4+): ≤ 0.04% 5) Heavy Metals (as Pb): ≤ 20 ppm 6) Arsenic: ≤ 2 ppm Inner packing:Plastic liner Outer packing: 25kg/multiple paper bags Shelf life: 2 years