L-Arginine monohydrochloride Synonym(s): (S)-(+)-2-Amino-5-[(aminoiminomethyl)amino]pentanoic acid monohydrochloride, (S)-(+)-Arginine hydrochloride Empirical Formula (Hill Notation): C6H14N4O2 · HCl CAS Number: 1119-34-2 Molecular Weight: 210.66