Nontarget Analysis of Halogenated Disinfection Byproducts in Brewed Tea and Coffee Using Ultra-High Performance Liquid Chromatography-High Resolution Mass Spectrometry

During tea and coffee brewing, residual chlorine in tap water can react with organic components to give rise to a variety of halogenated disinfection byproducts (HDBPs), potentially affecting human health. In this study, a non-target analysis method based on ultra-high performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) was developed for screening and identification of HDBPs in tea and coffee samples. After filtration and addition of isotopic internal standards, sample mixture was analyzed with UPLC-HRMS in negative electrospray ionization mode. Pure water containing 2 mmol/L ammonium acetate and acetonitrile was used as the mobile phases, and the gradient elution program was optimized. The mass spectrometric data were obtained with full scan and data-dependent acquisition (DDA) modes. According to exact masses, isotopologue distributions and chlorine substitution reaction rules, 82 kinds of HDBPs were identified, of which 59 contained 1 Cl, 15 contained 2 Cl, and 8 contained 3 Cl. Eight catechin-containing HDBPs were identified via MS/MS (DDA) spectra, fragmental pathways and retention times, and catechin, gallocatechin, catechin gallate and gallocatechin gallate were determined to be their precursors. In addition, toxicities of eight catechin-containing HDBPs were predicted by toxicity estimation software tool (T.E.S.T.). Finally, 82 kinds of HDBPs were semi-quantitatively analyzed, of which the concentrations in the samples brewed with tap water were 0.40-1897 & mu;g/L (black tea), 0.48-1157 & mu;g/L (green tea), 0.54-1168 & mu;g/L (oolong tea), 3.17-603.0 & mu;g/L (drip coffee), 1.32-138.0 & mu;g/L (capsule coffee) and 2.04-584.1 & mu;g/L (instant coffee), respectively. The developed non-target analysis method could readily identify HDBPs together with precursors without complicated pretreatment, which provided a new way to monitor HDBPs.