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 |