Nontarget screening of halogenated nucleotide analogs in water by chemical derivatization coupled with FT-ICR MS

It is a considerable challenge to identify and characterize halogenated nucleotide analogs, owing to the lack of authentic standards and the diversity of their structures. Nevertheless, nontargeted identification through high-resolution mass spectrometry (HRMS) provides an effective solution to this problem. In this study, typical nucleotides were selected as model compounds, and their binding products with N,N-dimethyl-p-phenylenediamine (DMPA) were identified to verify the feasibility of the derivatization method. The solid-phase extraction (SPE) pretreatment method and derivatization conditions were optimized to achieve optimal derivatization efficiency and detection sensitivity. Specifically, DMPA labeling was conducted at 60°C for 90 min, and the molar ratios of DMPA and 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) to nucleotides were set as 5 × 10 4 and 5 × 10 3 , respectively. Ultimately, the integration of chemical derivatization with HRMS analysis significantly enhanced the detection efficiency of the target compounds. As a result, using this optimized and model compound-validated method, 22 halogenated nucleotide analogs in a single natural water body were tentatively identified, and their precise molecular formulas were assigned by FT-ICR MS. The findings for this water body could provide new perspectives for the identification of emerging compounds in similar aquatic environments and offer novel approaches for elucidating the molecular characteristics of such pollutants.