| Definition | |
| Chemical name | Sodium bisulphite |
| Sodium hydrogen sulphite |
| Einecs | 231-921-4 |
| Chemical formula | NaHSO3 in aqueous solution |
| Molecular weight | 104,06 |
| Assay | Content not less than 32 % w/w NaHSO3 |
| Description | A clear, colourless to yellow solution |
| Identification | |
A.Positive tests for sulphite and for sodium | |
B.pH of a 10 % aqueous solution between 2,5 and 5,5 | |
| Purity | |
| Iron | Not more than 50 mg/kg of Na2SO3 based on the SO2 content |
| Selenium | Not more than 10 mg/kg based on the SO2 content |
| Arsenic | Not more than 3 mg/kg |
| Lead | Not more than 5 mg/kg |
| Mercury | Not more than 1 mg/kg |
| Heavy metals (as Pb) | Not more than 10 mg/kg |
