Simultaneous determination of multiple amino acids and their occurrence in drinking water systems in Zhejiang Province, China

A simultaneous analytical method was proposed for the determination of 13 kinds of free amino acids (FAAs) in the aqueous environment by high performance liquid chromatography (HPLC) combined with pre-column derivatization and solid-phase extraction technology. The recoveries for FAAs were between 8.9% and 87.6%, the detection limits of FAAs were in the range of 0.4-2.09 mg/L without enrichment pretreatment, the relative standard deviations were less than 0.6%. The method has been successfully applied to determine low concentrations of FAAs in real water samples. The occurrence of total FAAs in the source water of Hangzhou City ranged from 17.4 to 39.0 mu g/L. Tyr, Lys, and Asp were the dominant species and found with the highest concentrations of 13.4, 13.3, and 6.9 mu g/L, respectively. The conventional water treatment and advanced water treatment with ozonation and activated carbon were not ideal for the removal of FAAs, thus harmful disinfection byproducts might originated in the subsequent chlorination process, including regulated carbonaceous disinfection by-products (C-DBPs) and nitrogenous disinfection by-products (N-DBPs).