| Property | Specification | Test Method | Units |
|---|---|---|---|
| Appearance | White crystalline powder | Visual | – |
| Assay (as Na₂S₂O₅) | Min 95.0% (typical), may vary depending on grade | Titrimetry | wt% |
| Insoluble Matter in Water | Max 0.1% | Gravimetry | wt% |
| Free Sulfur (S) | Max 1.0% | Titrimetry or Iodometric Titration | wt% |
| Moisture | Max 0.5% | Karl Fischer Titration | wt% |
| Iron (as Fe) | Max 50 ppm | Atomic Absorption Spectroscopy (AAS) | ppm |
| Arsenic (as As) | Max 2 ppm | Inductively Coupled Plasma Mass Spectrometry (ICP-MS) | ppm |
| Lead (as Pb) | Max 10 ppm | Atomic Absorption Spectroscopy (AAS) | ppm |
