Qasim Ghulam Hussain, Harris Lisa, Mangal Vaughn, Montesdeoca Mario, Todorova Svetoslava, Driscoll Charles
Department of Civil and Environmental Engineering, Syracuse University, Syracuse, New York, USA.
Department of Chemistry, Brock University, St. Catharines, Ontario, Canada.
Rapid Commun Mass Spectrom. 2025 Apr 30;39(8):e9986. doi: 10.1002/rcm.9986.
The complexation with dissolved organic matter (DOM) is a pivotal factor influencing transformations, transport, and bioavailability of mercury (Hg) in aquatic environments. However, identifying these complexes poses a significant challenge because of their low concentrations and the presence of coexisting ions.
In this study, mercury-dissolved organic matter (Hg-DOM) complexes were isolated through solid-phase extraction (SPE) from Hg-humic acid suspensions, and complexes were putatively identified using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS).
Dissolved organic carbon (DOC) and total Hg analysis before and after SPE showed an increase in DOC:Hg ratio. The DOC:Hg ratio was lower in extracts from cartridges with silica structure bonded with hydrocarbon chains (C18) than priority pollutant (PPL) cartridges at circumneutral pH, indicating that C18 was more effective at extracting DOM complexed Hg. These results were confirmed with FTICR-MS analysis, where two Hg-DOM complexes were putatively identified from PPL extracts as opposed to eight from C18 (Winnow score > 75%). In addition, CHHgNOS, a molecular formula with a m/z ratio of 403.04, was identified across three separate extractions using a C18 cartridge, suggesting that the complexes were preserved during extraction and, presumably, electrospray ionization.
The results highlight the effectiveness of the methodology developed in this study-SPE coupled with FTICR-MS for isolating and identifying Hg-DOM complexes. This approach allows for the exploration of the elemental and structural composition of Hg-DOM complexes, which affects Hg speciation, bioavailability, and transformations in aquatic ecosystems.
A methodology was developed to identify Hg-DOM complexes at low concentrations to gain insight into mercury bioavailability, transformations, and transport in the environment.
与溶解有机物（DOM）的络合是影响水生环境中汞（Hg）转化、迁移和生物可利用性的关键因素。然而，由于这些络合物浓度较低且存在共存离子，鉴定它们面临重大挑战。
在本研究中，通过固相萃取（SPE）从汞-腐殖酸悬浮液中分离出汞-溶解有机物（Hg-DOM）络合物，并使用超高分辨率傅里叶变换离子回旋共振质谱（FTICR-MS）对络合物进行推定鉴定。
固相萃取前后的溶解有机碳（DOC）和总汞分析表明，DOC:Hg比值增加。在中性pH条件下，与优先污染物（PPL）柱相比，具有碳氢链键合硅胶结构（C18）的柱提取物中的DOC:Hg比值更低，这表明C18在提取与DOM络合的汞方面更有效。这些结果通过FTICR-MS分析得到证实，其中从PPL提取物中推定鉴定出两种Hg-DOM络合物，而从C18提取物中鉴定出八种（筛选分数>75%）。此外，使用C18柱在三次单独萃取中均鉴定出分子式为CHHgNOS、质荷比为403.04的物质，这表明络合物在萃取过程中得以保留，并且大概在电喷雾电离过程中也得以保留。
结果突出了本研究中开发的方法——固相萃取与FTICR-MS联用——在分离和鉴定Hg-DOM络合物方面的有效性。这种方法有助于探索Hg-DOM络合物的元素和结构组成，而这会影响水生生态系统中汞的形态、生物可利用性和转化。
开发了一种方法来鉴定低浓度的Hg-DOM络合物，以深入了解汞在环境中的生物可利用性、转化和迁移。
