Target quantification and semi-target screening of halogenated carboxylic acids in drinking water using ultra-high...

To monitor the existing and emerging halogenated carboxylic acids (HCAs) in drinking water, a sensitive and rapid ultra-high performance liquid chromatography-quadrupole orbitrap high-resolution mass spectrometry method for simultaneous target quantification of 10 haloacetic acids (HAAs) and semi-target screening of 19 HCAs was developed. After filtration, drinking water samples were injected into the instrument. HCAs were separated on an HSS T3 column and detected by a type of non-target scan in the electrospray ionization negative mode. For target quantification of 10 HAAs, good linearity was obtained and the correlation coefficients were higher than 0.995. The limits of detection were in the range of 0.050-2.0 µg/L. The recoveries were in the range of 89.7%-108%, 83.4%-121%, 77.1%-116% and 80.2%-104% at levels of 2.5, 5.0, 10 and 20 µg/L, respectively, with relative standard deviations of 1.26%-16.9%. For semi-target screening of 19 HCAs, several criteria including accurate m/z, predicted retention time, deduced fragment ions and simulated isotope pattern were used for identification. The method was applied to analyzing 41 drinking water samples successfully. Five HAAs were detected by target quantification, with dichloroacetic acid and trichloroacetic acid exceeding the limits suggested by the U.S. Environmental Protection Agency and the World Health Organization. Eight HCAs were preliminary identified by semi-target screening, and three of them were further confirmed with reference standards purchased later.