| White to colorless solid | Complying |
| Assay (T) | 99.0-101.0%w/w |
| pH (5% in water) | 4.1-4.5 |
| Loss on drying (105°C) | <= 0.2% |
| Chloride (Cl) | <= 0.001% |
| Heavy metals (as Pb) | <= 0.001% |
| Iron (Fe) | <= 0.002% |
| Sulfate (SO4) | <= 0.003% |
| Sodium (Na) | <= 0.005% |
| Water insolubles | <= 0.01% |