| Property | Specification | Test Method |
|---|---|---|
| Assay (Na₂SO₄) | ≥ 98.0% (anhydrous) | Gravimetry or Titrimetry |
| Appearance | White crystalline powder | Visual |
| Solubility in Water | Soluble | USP or Ph. Eur. 2.9.3 |
| pH (1% solution) | 5.0 – 9.0 | Potentiometry |
| Loss on Drying | ≤ 1.0% | USP or Ph. Eur. 2.2.32 |
| Water Insoluble Matter | ≤ 0.2% | USP or Ph. Eur. 2.8.1 |
| Chloride (Cl) | ≤ 0.01% | Ion Chromatography |
| Sulfate (SO₄) (if applicable) | ||
| Heavy Metals (as Pb) | ≤ X ppm | USP or Ph. Eur. 2.4.8 |
| Iron (Fe) | ≤ X ppm | AAS or ICP-OES |
