Development of a Method for Analysing Persistent, Mobile and Toxic Compounds, from Groundwater to Drinking Water, using LC-HRMS

The growing pressure on water resources is leading to drinking water shortages and increased pollution. Certain persistent, mobile, and toxic (PMT) substances in aquatic environments have intrinsic properties that allow them to remain in the environment, pass through filtration systems, and withstand conventional drinking water treatments. They can accumulate, especially when wastewater is recycled, eventually reaching resources intended for drinking water. Current data on PMT contamination in water resources is limited, raising significant environmental and public health concerns. In this context, this study focuses on analysing PM/PMT substances in groundwater, surface water, and drinking water of 4 locations around the world with a gradient of anthropic pressure on the water resources from no pressure a priori to increasing pressures depending on water treatment and reuse practices. The initial step of this study was to develop a sample preparation protocol and an LC-MS (liquid chromatography-mass spectrometry) method suited to these compounds. A literature review of 480 PM/PMT molecules resulted in the selection of 59 compounds from various categories (pharmaceuticals, pesticides, and REACH-regulated chemicals) for targeted analytical method development keeping in mind that a broader suspect screening approach will be also conducted. To achieve an optimal sample preparation and analysis of PMT substances, five solid-phase extraction (SPE) protocols with different cartridges (Hydrophilic-Lipophilic Balance (HLB), Weak Anion Exchange (WAX), ENVI-Carb™, Mixed-mode Anion Exchange (MAX), and Mixed-mode Cation Exchange (MCX)) were tested on the 59 selected compounds. For LC-MS analysis, four chromatographic columns (Biphenyl, BEHC18, Cortecs T3, and Acclaim Trinity P1) with various mobile phases were also evaluated.Following evaluation, the Acclaim Trinity P1 chromatographic column demonstrated superior performances in terms of retention of polar analytes and sensitivity. Regarding sample preparation, 2 complementary methods were selected: HLB and WAX. The HLB cartridge achieved superior results, delivering higher recoveries and lower matrix effects for 43 compounds. Additionnaly, the WAX cartridge enhanced the extraction of 8 additional compounds that were insufficiently retained by the HLB cartridge. Application of this optimised method on real samples collected in the frame of project revealed the presence of various PM/PMT substances.