Chlorination studies of free and combined amino acids

Abstract

Abstract Nitrogenous organic compounds in raw and treated water are of concern because they may exert high chlorine demand. They are also known as precursors of halogenated compounds. In this study, chlorine demand, TOX and THM formation potentials of 22 free amino acids, and some polypeptides and proteins were determined. Results have shown that the reactivity of free amino acids with chlorine is related to their structure. Experiments conducted with combined amino acids have shown that the amide linkage does not participate significantly in the chlorine demand of polypeptides, and does not seem to be TOX precursor. Specific amino acids that possess reactive side groups such as amino nitrogen, sulfur or activated aromatic ring were defined as the main chlorine consumer and TOX precursor sites of polypeptides. Complementary experiments indicated that sodium sulfite dechlorination can affect, more or less, the determination of amino acids TOXFP.