E 450 (iii) TETRASODIUM DIPHOSPHATE
| Synonyms | Tetrasodium pyrophosphate; Tetrasodium disphosphate; Tetrasodium phosphate |
| Definition | |
|---|---|
| Einecs | 231-767-1 |
| Chemical name | Tetrasodium diphosphate |
| Chemical formula | Anhydrous: Na4P2O7 Decahydrate: Na4P2O7 · 10H2O |
| Molecular weight | Anhydrous: 265,94 Decahydrate: 446,09 |
| Assay | Content not less than 95 % of Na4P2O7 on the ignited basis P2O5 content not less than 52,5 % and not more than 54,0 % |
| Description | Colourless or white crystals, or a white crystalline or granular powder. The decahydrate effloresces slightly in dry air |
| Identification | |
| Test for sodium | Passes test |
| Test for phosphate | Passes test |
| Solubility | Soluble in water. Insoluble in ethanol |
| pH | Between 9,8 and 10,8 (1 % solution) |
| Purity | |
| Loss on ignition | Not more than 0,5 % for the anhydrous salt, not less than 38 % and not more than 42 % for the decahydrate (105 °C, 4 hours then 550 °C, 30 minutes) |
| Water insoluble matter | Not more than 0,2 % |
| Fluoride | Not more than 10 mg/kg (expressed as fluorine) |
| Arsenic | Not more than 1 mg/kg |
| Cadmium | Not more than 1 mg/kg |
| Lead | Not more than 1mg/kg |
| Mercury | Not more than 1 mg/kg |