High-performance liquid chromatographic analysis of amino acid- and peptide-derived chloramines

An isocratic reversed-phase high-performance liquid chromatographic method is reported for the analysis of amino acid- and peptide-derived chloramines (these are important intermediates in two very different processes: destruction of microbes by the neutrophil and disinfection of water with chlorine). Specifically, results are reported for the chloramines derived from the following amino acids and dipeptides: taurine, Ala, Gly, Ser, Thr, Phe, Val, AlaGLy, GlyGly, PheGly, SerGly, and ValGly. Analyses are performed on a 250 × 4.6-mm C18 column using a buffered water-acetonitrile mixture as the mobile phase. For samples containing hydrophilic chloramines, an ion-pairing agent is added to the mobile phase. Two detection methods are used: direct ultraviolet (UV) detection of the chloramine at 254 nm and indirect UV detection of I3- at 350 nm following postcolumn reaction with iodide. Unexpectedly, the decomposition of amino acid-derived chloramines is found to greatly accelerate during chromatographic elution on a reversed-phase column.