Improved identification of chlorinated disinfection byproducts by the sequential elution and absorption mode

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been extensively employed to characterize the chemodiversty of dissolved organic matter (DOM) including chlorinated disinfection byproducts (Cl_n-DBPs). However, little is known about the combined effects of the sequential solid phase extraction (SPE) and absorption mode of Fourier transform data processing on the identification of Cl_n-DBPs. In this study, the identification of Cl_n-DBPs by the sequential SPE extraction and absorption mode were systematically compared using a typical swimming pool water. The sequential SPE extraction was more effective in extracting DOM molecules including Cl_n-DBPs than the traditional extraction, yielding 48.2 % ± 2.1 % and 87.3 % ± 3.8 % more DOM molecules and Cl_n-DBPs molecules, respectively. Moreover, a total of 274 nitrogenous Cl_n-DBPs were identified by the sequential SPE extraction with 80 more than that by the traditional SPE. The absorption mode improved the resolution and the signal-to-noise values of DOM peaks by factors of 1.87-1.98 and 1.52-1.60, respectively. The number of resolved Cl-related mass doublets within 2 mDa mass difference in the absorption mode was 537 more than that in the magnitude mode. Overall, the combination of sequential elution and absorption modes facilitated the detection of more molecules of DOM and Cl_n-DBPs compared to traditional SPE in magnitude mode, with an increase of 92.7 % ± 2.1 % and 121.7 % ± 5.6 %, respectively. These results have highlighted the great potential of the sequential elution combined with absorption mode in improving the identification of Cl_n-DBPs and their precursors, facilitating the application of FT-ICR MS in the nontargeted analysis of emerging contaminants including Cl_n-DBPs at the molecular level.