A complete set of nontargeted analysis method was established by combining the high-resolution MS and the characteristic mass spectrometry properties of iodinated disinfection byproducts (I-DBPs). Groundwater samples were collected from 17 sites in Hebei Province, and an integrated nontarget screening workflow was developed and implemented to identify the category, quantity and distribution of I-DBPs in the groundwater samples. As a result, a total of 2408 suspect I-DBPs ions including isomers were screened, of which 839 unique mass-to-charge ratios were identified, much higher than the numbers reported by previous studies. Among the suspect I-DBPs ions, the structures were carefully analyzed for precursors which were detected with top 10 the most abundant iodide ions in their MS/MS spectra, and the top 2 suspect ions were identified as phenolic I-DBPs, whose developmental toxicity are tens to hundreds of times higher than the corresponding aliphatic DBPs. Further analysis confirmed that the phenolic I-DBPs were one of the main categories of all the I-DBPs detected in samples. Finally, the distribution characteristics of 2408 suspect ions were analyzed based on principal component analysis (PCA). According to the PCA, 3 sites significantly different from other sampling sites were screened as outlier sites. The suspect ions were clustered into 4 classes using Gaussian mixture model according to their loading scores, and ions from 3 of 4 classes were identified as the diagnostic pollutants for 3 outlier sites respectively. The results highlighted the differences and complexity of I-DBPs in groundwater of Hebei Province.

iodinated disinfection byproducts (I-DBPs), nontarget screening, high-resolution mass spectrometry, groundwater, principal component analysis