1 | Description | White powder; odour, sulphurous. | Colourless, prismatic crystals or a white or creamy white powder; odour, sulphurous. |
2 | Solubility | Complies | Freely soluble in water; slightly soluble in ethanol (95%) |
3 | Identification A (Reaction of Sodium) | Complies | A dense white precipitate should form. |
4 | Identification B (Reaction of sulfates) | Complies | White precipitate should form. |
5 | pH | 4.14 | 3.5 to 5.0 |
6 | Arsenic (As) | Less than 4 ppm | NMT 4 ppm |
7 | Heavy metals | Less than 20 ppm | NMT 20 ppm |
8 | Iron (Fe) | Less than 40 ppm | NMT 40 ppm |
9 | Thiosulphate | Complies | Not more than a faint opalescence should produced. |
10 | Assay | 96.7% | 95.0% - 100.5% |