| Appearance | Colorless crystals or white crystalline powder |
| Assay | 99.0 – 100.5% |
| Identity (acc. to pharmacopoeias) | Passes test |
| Appearance of solution | Passes test |
| Insoluble matter in water | Max 0.01% |
| pH (1% solution in water) | 4.1-4.7 |
| pH (5% solution in water; 20°C) | 4.2-4.5 |
| pH (5.7% solution in water) | 4.1-4.5 |
| Chloride (Cl) | Max 0.001% |
| Sulphate (SO4) | Max 0.005% |
| Aluminium, calcium and related elements | Passes test |
| Substance reducing KMnO4 (as O) | Passes test |
| Arsenic (As) | Max 0.0002% |
| Calcium (Ca) | Max 0.002% |
| Iron (Fe) | Max 0.001% |
| Heavy metal (as Pb) | Max 0.0005% |
| Magnesium (Mg) | Max 0.001% |
| Potassium (K) | Max 0.005% |
| Loss on drying (at 130°C) | 21.5 – 24.0% |
