L-Cysteine . hydrochlorideProduct SpecificationAlternative Name: H-L-Cys-OH . HCl Formula: C3H7NO2S . HCl MW: 121.2 . 36.5 CAS: 52-89-1 MI: 14: 2781 RTECS: HA2275000 Purity: ≥98% (TLC) Appearance: White to off-white solid. Hazard: IRRITANT. Solubility: Soluble in water (50mg/ml). Long Term Storage: Ambient Handling: Hygroscopic.