COMPREHENSIVE NON-TARGET SCREENING OF ALPINE SNOW AND SURFACE WATERS BY COMPLEMENTARY LC-HRMS AND GC-MS

Introduction Non-target screening (NTS) by high-resolution mass spectrometry (HRMS) has become a key approach for comprehensive characterization of complex environmental samples, including snow matrices. Alpine environments are recognized as sensitive receptors of long-range atmospheric transport of contaminants of emerging concern (CECs), where their chemical complexity remains poorly characterized. These samples pose significant analytically challenges due to their trace-level concentrations and wide polarity ranges. Combination of complementary extraction methods with orthogonal chromatographic separation techniques is therefore essential to improve the detection of diverse CECs. In this study, complementary LC-HRMS and GC-MS non-target workflows were applied to snow and river water samples from the Monte Bianco region to evaluate analytical complementarity, characterize spatial chemical fingerprints, and detect previously unreported CECs. Methods Surface snow and river water samples were collected at different altitudes and along upstream–downstream sites in the area of Monte Bianco. Samples were pre-concentrated with two complementary approaches, solid-phase extraction (HLB, MAX, and WAX cartridges) targeting polar and semi-polar compounds, and lyophilization followed by solvent extraction for semi-volatile and volatile analytes. The non-target analysis was performed by UHPLC coupled to an Orbitrap Exploris 120 mass spectrometer operated in ESI positive and negative modes using full-scan data-dependent acquisition, and by GC-MS in full-scan mode. Data processing followed a structured non-target workflow with defined quality criteria to ensure robust compound identification. Preliminary Data Non-target screening revealed chemically diverse contamination profiles in snow and river water samples. More than 200 compounds were tentatively identified across matrices, most of them attributed to anthropogenic sources, including personal-care products, industrial chemicals, pharmaceuticals, and pesticides. The use of multiple SPE sorbents significantly increased the number and diversity of CECs detected. Complementary lyophilization followed by GC-MS analysis enabled the detection of hydrophobic and semi-volatile compounds that were not observed by LC-HRMS alone. Several compounds, such as phthalates, organophosphate flame retardants, and personal care product, were consistently detected in both snow and water samples, indicating widespread environmental dispersion. Multivariate statistical analysis (PCA) allowed clear discrimination between snow and water samples, as well as between high- and low-altitude snow and upstream versus downstream river sites. These compositional differences suggest spatial contamination patterns linked to altitude and sampling location, likely influenced by long-range atmospheric deposition and local anthropogenic activities. These preliminary results reveal that combining complementary extraction techniques with LC-HRMS and GC-MS non-target workflows allowed a comprehensive understanding of CECs occurrence in remote alpine environments. Novel Aspect Integrated SPE and lyophilization workflows combined with LC-HRMS and GC-MS for comprehensive non-target analysis of alpine snow and water.