Specification:
| ITEM | STANDARD |
| Appearance | White crystals or crystalline powder |
| Assay (as NH4HCO3, %) | 99.0-100.5 |
| Chlorides (as Cl, %) | =< 0.003 |
| Sulfur compound (as SO4, %) | =< 0.007 |
| Residue after evaporation (%) | =< 0.008 |
| Specific optical rotation | +20.5° ~ +21.5° |
| Lead | =< 3 mg/kg |
| Arsenic | =< 2 mg/kg |
| Total Heavy metal (as Pb) | =< 10 mg/kg |