| Definition | |
| Chemical name | Sodium methyl p-hydroxybenzoate |
| Sodium compound of the methylester of p-hydroxybenzoic acid |
| Chemical formula | C8H7O3Na |
| Molecular weight | 174,15 |
| Assay | Content not less than 99,5 % on the anhydrous basis |
| Description | White, hygroscopic powder |
| Identification | |
A.The white precipitate formed by acidifying with hydrochloric acid a 10 % (w/v) aqueous solution of the sodium derivative of methyl p-hydroxybenzoate (using litmus paper as indicator) shall, when washed with water and dried at 80 oC for two hours, have a melting range of 125 oC to 128 oC | |
B.Positive test for sodium | |
C.pH of a 0,1 % solution in carbon dioxide free water, not less than 9,7 and not more than 10,3 | |
| Purity | |
| Water content | Not more than 5 % (Karl Fischer method) |
| Sulphated ash | 40 % to 44,5 % on the anhydrous basis |
| p-Hydroxybenzoic acid and salicylic acid | Not more than 0,35 % expressed as p-hydroxybenzoic acid |
| 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 |
