| Definition | L-cysteine hydrochloride or hydrochloride monohydrate. Human hair may not be used as a source for this substance |
| Einecs | 200-157-7 (anhydrous) |
| Chemical formula | C3H7NO2S· HCl· n H20 (where n = 0 or 1) |
| Molecular weight | 157,62 (anhydrous) |
| Assay | Content not less than 98,0 % and not more than 101,5 % on the anhydrous basis |
| Description | White powder or colourless crystals |
| Identification | |
A. Solubility | Freely soluble in water and in ethanol |
B. Melting range | Anhydrous form melts at about 175 oC |
C. Specific rotation | [α]20 D: between 5,0o and 8,0o or |
| [α]25 D: between 4,9o and 7,9o |
| Purity | |
| Loss on drying | Between 8,0 % and 12,0 % |
| Not more than 2,0 % (anhydrous form) |
| Residue on ignition | Not more than 0,1 % |
| Ammonium-ion | Not more than 200 mg/kg |
| Arsenic | Not more than 1,5 mg/kg |
| Lead | Not more than 5 mg/kg |
