| Property | Specification | Test Method |
|---|---|---|
| Assay (H₃NSO₃) | ≥ 99.0% | Titrimetry |
| Appearance | White, crystalline powder | Visual |
| pH (1% solution) | 1.0 – 2.0 | Potentiometry |
| Melting Point | 205°C (decomposition) | |
| Moisture Content | ≤ 0.5% | Karl Fischer Titration |
| Insoluble Matter | ≤ 0.1% | Gravimetry |
| Chloride (Cl) | ≤ 0.005% | Ion Chromatography |
| Iron (Fe) | ≤ X ppm | Atomic Absorption Spectroscopy (AAS) |
| Heavy Metals (as Pb) | ≤ 0.001% | AAS |
