Solid-Phase Reactivity-Directed Extraction (SPREx):\nAn Alternative Approach for Simultaneous Extraction, Identification,\nand Prioritization of Toxic Electrophiles Produced in Water Treatment\nApplications

Current strategies\nto assess water quality are ineffective at prioritizing\nthe most toxic chemicals within a treated water sample. Although it\nis well known that oxidation byproducts (OBPs) from water treatment\nprocesses (e.g., chlorination and ozonation) are linked to adverse\nhealth outcomes such as skin diseases, reproductive toxicity, and\nvarious cancers, we are still unable to account for a large fraction\nof the toxicity drivers. Previous approaches utilize <i>in vitro</i> or <i>in vivo</i> assays to assess OBPs on an individual\nbasis, which is too time- and resource-intensive considering the countless\nnumber of transformation byproducts of unknown toxicities that exist\nin treated waters. <i>In vitro</i> assays have also been\ndeveloped to analyze the toxicity of OBPs in environmental mixtures,\nbut these approaches do not provide identification information about\nthe responsible toxicants. Furthermore, an additional challenge for\nOBP detection arises during the extraction and detection stages of\nanalysis, as certain OBPs are typically lost using traditional extraction\nmethods or are not detectable via liquid-chromatography–high-resolution\nmass spectrometry (LC-HRMS) without derivatization. To address these\nissues, we have developed the analytical assay <u><b>S</b></u>olid-<u><b>P</b></u>hase <u><b>R</b></u>eactivity-directed <u><b>Ex</b></u>traction (SPREx), which aims to provide an all-in-one\nevaluation for (i) <i>in chemico</i> toxicity screening,\n(ii) extraction, (iii) detection, and (iv) identification via LC-HRMS.\nThe performance of SPREx was evaluated by testing different nucleophile\nprobes for the capture and detection of 24 different carbonyl compounds,\nwhich serve as model electrophiles and are known OBPs that provide\nunique extraction and detection challenges. SPREx provided distinct\nadvantages for extraction recoveries and was an effective screening\ntool for carbonyl detection and quantification in complex water matrices\n such as drinking water and wastewater.