2,2-Dimethylcysteine

Mixed-mode chromatography allows separating, in single run, compounds with vastly different properties. A method for separation of amino acids (cysteine, methylcysteine, cystine and dimethylcysteine) in the presence of carboxylic acid (benzoic) and hydrophobic neutral compounds was developed on Primesep 100 mixed-mode column. At lower pH ionization of carboxylic acids is suppressed. Amino acids are retained as basic compound based on reverse phase and cation exchange mechanisms. Carboxylic acids are retained on this column based on weak reverse phase mechanisms. Neutral compounds are retained by reverse phase mechanism as on any other column. Retention time of basic, zwitter-ionic and hydrophobic compound can be adjusted by manipulation of mobile phase composition. ELSD, UV or LC/MS detection can be used based on the properties of analytes and mobile phase selection.

Primesep 100 separates a mixture of polar and nonpolar compounds in one analytical run. The amino acid cysteine; amino acid derivatives L-cystine, 2,2-dimethylcystine, and 2-methylcysteine; the polar acid benzoic acid; and the nonpolar neutral toluene are separated by a gradient using a combination of polar and hydrophobic interactions. The separation method uses a mobile phase mixture of water, acetonitrile (MeCN, ACN) and sulfuric acid (H2SO4) with UV detection at 210 nm.