Methodological features of chromato-mass spectrometric identification of organic compounds in the air during landscape fires

Abstract

Introduction. In landscape fires, the question of the nature and character of the formed organic substances remains unexplored. The method of gas chromatography with mass spectrometric detection (GC-MS) has long been used in environmental analysis to identify organic compounds in complex multicomponent mixtures. Depending on the volatility and polarity of the components of organic compounds, air sampling is carried out on a solid sorbent, liquid absorber, fiber filter. The purpose of this study is to develop a comprehensive procedure for the identification of organic compounds by gas chromatography-mass spectrometry with sampling into different absorption media. Materials and methods. The studies were carried out in laboratory conditions specially created in the smoldering plant, seed chamber, chemical-analytical equipment. Biomass consisting of forest litter was used as a fuel substrate: moss, lichen, tree litter, branches, pieces of bark. An Agilent 5975 gas chromatography-mass spectrometer was used for GC-MS identification. An aspirator, a gas pipette, a Richter absorber with distilled water, and an AFA-HP-20 fiber filter were used to select the air medium. Sample preparation of concentrated air was carried out using microfibre “85 microns Carboxen/PDMS”, thermostat, vials for vapor phase analysis, ultrasonic bath, derivatizing reagent - o-pentafluorobenzylhydroxylamine, hexane. Results. A proposed complex procedure includes sampling into different absorption media, various sample preparation options. Extraction of organic compounds from absorption media was carried out by methods of solid-phase microextraction, derivatization, and liquid extraction. Volatile organic compounds were extracted from a gas bulb by the method of solid-phase microextraction on microfibre“85 microns Carboxen/PDMS”. Aldehydes and ketones were found in distilled water due to the derivatization of o-pentafluorobenzylhydroxylamine. Semi-volatile compounds were detected on the AFA-HP-20 filter due to liquid extraction in ultrasound. Limitations. The limitations of the study are related to the need to select the products of decay of a sample of forest litter under model conditions. Conclusion. The identification results showed that the following classes of substances released into the air during the burning of forest litter are present in the maximum amount: aldehydes, phenols, terpenes. The coefficient of coincidence of mass spectra also confirmed by the coincidence of experimental and library retention indices also confirmed by the coincidence of experimental and library retention indices is more than 90%.