| Synonyms | Potassium pyrophosphate |
| Tetrapotassium pyrophosphate |
| Definition | |
| Chemical name | Tetrapotassium diphosphate |
| Einecs | 230-785-7 |
| Chemical formula | K4P2O7 |
| Molecular weight | 330,34 (anhydrous) |
| Assay | Content not less than 95 % on the ignited basis |
| P2O5 content | Not less than 42,0 % and not more than 43,7 % on the anhydrous basis |
| Description | Colourless crystals or white, very hygroscopic powder |
| Identification | |
A.Positive tests for potassium and for phosphate | |
B.Solubility | Soluble in water, insoluble in ethanol |
C.pH of a 1 % solution | Between 10,0 and 10,8 |
| Purity | |
| Loss on ignition | Not more than 2 % after drying at 105 oC for four hours and then ignition at 550 oC for 30 minutes |
| Water-insoluble substances | Not more than 0,2 % |
| Fluoride | Not more than 10 mg/kg (expressed as fluorine) |
| Arsenic | Not more than 3 mg/kg |
| Cadmium | Not more than 1 mg/kg |
| Lead | Not more than 4 mg/kg |
| Mercury | Not more than 1 mg/kg |
