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Per- and polyfluoroalkyl substances (PFASs) are exceptionally stable chemicals due to their strong CF bonds. Nanoscale zero-valent iron (nZVI) particles have the potential to remove and degrade PFASs through redox activity. In this study, we deposited nZVI onto two-dimensional reduced graphene oxide (rGO) nanosheets and tested these synthesized rGO-nZVI nanohybrid (NH) for the treatment of a mixture of short- and long-chain PFASs in water with and without H2O2. All PFASs were removed at a higher efficiency by the rGO-nZVI NH than by the parent materials rGO and nZVI. Notably, the long-chain PFASs were removed at a faster rate than the short-chain PFASs. After a 10 min exposure to the rGO-nZVI NH without H2O2, the long-chain PFASs (perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)) were removed by 85 % and 39 %, respectively, while short-chain PFASs (perfluoropentane sulfonic acid and perfluoropentanoic acid) were removed by 19 % and 18 %, respectively. The addition of H2O2 enhanced the PFAS treatment performance by 10–18 %, which can be attributed to the generation of reactive oxygen species by the rGO-nZVI NH. Liquid chromatography high-resolution mass spectrometry analysis confirmed the formation of unique shorter chain and partially defluorinated PFAS-Fe complexes from both PFOS and PFOA.

The vast number of chemicals potentially reaching aquatic environment pose a challenge in maintaining the quality of water resources. However, best management practices to improve water quality are typically focused on reducing nutrient transport without assessing how these practices may impact the occurrence of micropollutants. The potential for co-management of nutrients and organic micropollutants exists, but few studies have comprehensively evaluated the suite of contaminants associated with different water quality management practices (riparian zone restoration, stormwater management, etc.). Furthermore, most studies dealing with the determination of micropollutants in environmental samples include only a limited number of target analytes, leaving many contaminants undetected. To address this limitation, there has been a gradual shift in environmental monitoring from using target analysis to either suspect screening analysis (SSA) or non-targeted analysis (NTA), which relies on accurate mass measurements, mass spectral fragmentation patterns, and retention time information obtained using liquid chromatography coupled to high-resolution mass spectrometry. The work presented in this paper focuses on a wide-scope detection of micropollutants in surface water samples from the Potomac River watershed (United States). An in-house database composed of 1039 compounds based on experimental analysis of primary standards was established, and SSA workflow was optimized and applied to determine the presence of micropollutants in surface water. A total of 103 micropollutants were detected in the samples, some of which are contaminants that were not previously monitored and belong to various classes such as pharmaceuticals, personal care products, per-and polyfluoroalkyl substances and other persistent industrial chemicals. The impact of best management practices being implemented for nitrogen and phosphorus reductions were also assessed for their potential to reduce micropollutant transport. This work illustrates the advantages of suspect screening methods to determine a large number of micropollutants in environmental samples and reveals the potential to co-manage a diverse array of micropollutants based on shared transport and transformation mechanisms in watersheds.

Cardiac glycosides, steroid derivatives extracted from the foxglove plants, have been used for the treatment of heart failure since the 18th century. A method based on liquid chromatography coupled with high-resolution tandem mass spectrometry (LC/MS2) has been developed to characterize and quantify cardiac glycosides in fresh-leaf extracts of the foxglove (Digitalis sp.) plants [1]. In this report, the fragmentation spectra of additional authentic standards of cardiac glycoside (digitoxigenin, digoxigenin, β-acetyldigoxin) and cardenolides identified in the leaves of Digitalis lanata (D. lanata) and Digitalis purpurea (D. purpurea) were provided with high resolution. The exact mass of signature peaks for the aglycones and the sugar units of cardenolides were measured. This dataset is valuable to researchers interested in characterizing cardenolides in plants, or quantifying cardenolides in drug tablets, or studying cardenolide toxicities in animals. The fragmentation patterns of authentic cardenolide standards provided in these data can be used to validate relevant cardenolides in various biological samples and to infer chemical structures of unknown cardiac glycosides.