ИСТИНА

Introduction Environmental exposure assessment is an important step in establishing a list of local priority pollutants and finding the sources of the threats. Arkhangelsk is the largest city of North-European part of Russia, where a number of industrial facilities are located. Arkhangelsk experiences subarctic climate with heavy snowfalls during 7 months. Therefore, snow analysis represents an efficient approach for the estimation of long-term air pollution during winter period due to accumulation and preservation of environmental contaminants by snow. Methods Ten snow samples were collected in January 2021 in Arkhangelsk. Classical liquid-liquid extraction of molten water with dichloromethane was used for sample preparation. The extracts were analyzed using Pegasus GC-HRT+ 4D highresolution mass spectrometer combined with Agilent 7890A gas chromatograph in the GC×GC mode. Identification and quantification of priority pollutants was done using standards, while NIST20 mass spectral library together with manual structural elucidation were used for identification of unexpected or unknown compounds. Quantification of some other environmentally relevant compounds, for which the standards were missing, was carried out considering the response factors being equal to 1. Preliminary data (results) In addition to the classic priority pollutants listed by the US EPA (polycyclic aromatic hydrocarbons, phenols, phthalates, etc.), non-target analysis allowed identifying a wide range of organic compounds, including alkyl pyridines, organophosphates, furans, organic acids, etc. 3 different data processing approaches were used for the obtained data set. Chemometric data processing methods were used to identify the differences in the nature of pollutants between the snow sampling sites. The novel ChromaTOF Tile program provided by LECO Company, free access Metaboanalyst software and custom designed software were used for sample clusterization. ChromaTOF Tile program automatically determines the differences in two-dimensional spectra between samples and uses the found features to plot PCA graph and hence perform clusterization.Metaboanalyst is well known free of charge internet resource for data processing which allows using different chemometric approaches, while the custom software was used to have the ability of varying the clusterization parameters in a more detailed manner and determine the number of clusters. Application of chemometric methods of data processing made it possible to identify the most significant pollutants at each sampling point and to draw up a pollution map of the Arkhangelsk city.