## 4 Discussion  
Biological systems and objects have been traditionally studied using spectroscopy methods. However, as a rule, these studies pursued only utilitarian goals: tracing the  
Figure 8: The chemical composition of products of thermal decomposition for samples of relatively healthy mucosa (blue), cyst (green), and polyp (red). Figure 7: Examples of recording spectrum sections containing acetonitrile (CH\({}_{3}\)CN) lines for cyst samples (green curve) and for polyp samples (red curve) with different concentrations of acetonitrile in thermal decomposition products. The spectrum of polyp sample contains the methylbutyronitrile ((CH3)2 CHCH2 CN) absorption line. (**a**) Acetonitrile lines with frequencies f\({}_{\text{lexp}}\) = 165.4544 GHz, f\({}_{\text{lext}}\) = 165.454369 GHz; f\({}_{\text{lexp}}\) = 165.48936 GHz, f\({}_{\text{lext}}\) = 165.4893907 GHz; f\({}_{\text{lexp}}\) = 165.5182 GHz, f\({}_{\text{scxt}}\) = 165.5180638 GHz; f\({}_{\text{texp}}\) = 165.5405 GHz, f\({}_{\text{scxt}}\) = 165.5540377 GHz; f\({}_{\text{scxt}}\) = 165.5563 GHz, f\({}_{\text{scxt}}\) = 165.5563219 GHz; f\({}_{\text{texp}}\) = 165.5659 GHz, f\({}_{\text{scxt}}\) = 165.568913 GHz; and f\({}_{\text{exp}}\) = 165.5692 GHz, f\({}_{\text{scxt}}\) = 165.5690816 GHz. (**b**) Acetonitrile lines with frequencies f\({}_{\text{lexp}}\) = 166.0136 GHz, f\({}_{\text{lext}}\) = 166.0134004 GHz; f\({}_{\text{lexp}}\) = 166.0361 GHz, f\({}_{\text{scxt}}\) = 166.0358883 GHz; f\({}_{\text{lexp}}\) = 166.0429 GHz, f\({}_{\text{scxt}}\) = 166.0428265 GHz; f\({}_{\text{texp}}\) = 166.0516 GHz, f\({}_{\text{scxt}}\) = 166.0515011 GHz; f\({}_{\text{sct}}\) = 166.0590 GHz, f\({}_{\text{scxt}}\) = 166.0588124 GHz and f\({}_{\text{scxt}}\) = 166.0592874 GHz; f\({}_{\text{lexp}}\) = 166.07132 GHz, f\({}_{\text{scxt}}\) = 166.0712258 GHz; and methylbutyronitrile line with frequencies f\({}_{\text{lexp}}\) = 166.0208 GHz, f\({}_{\text{lcat}}\) = 166.0206676 GHz, where f\({}_{\text{lexp}}\) are experimentally measured central frequencies and f\({}_{\text{lcat}}\) are frequencies from spectroscopy databases [11,12]. appearance or changes of a given chemical substance during a pathological process. Metabolomics, a new scientific discipline that emerged at the end of the twentieth century, focuses on the study of the final and intermediate products of metabolism with the goal of compiling a metabolic profile that reflects the characteristics of the disease [3]. From this point of view, an innovative method is high-resolution gas spectroscopy in the terahertz range that makes it possible to detect the largest number of metabolites in different media and tissues and, by analyzing the number of absorption lines, to trace markers characteristic of a particular pathological process [6; 17]. We have analyzed an assembly of metabolites with the prospect of creating a characteristic metabolic profile with the detection of markers of the pathological process in the sphenoid and maxillary sinuses by the number of absorption lines. First of all, it should be noted that the absorption lines of acetaldehyde, methyl mercaptan, propenediol, azole, benzonitrile, ethylene sulfide, sulfur oxide, and carbon sulfide are identified both in the spectra of samples of relatively healthy mucosa and in the spectra of polyp and cyst tissues. This allows us to conclude that these substances can be considered markers compiling the metabolic profile of healthy tissue. The analyses of the absorption spectra of polyp and cyst samples demonstrated that the concentration of these substances increases many times when compared to healthy tissue. In addition, during the thermal decomposition of pathological tissue samples, there appear substances such as acetone, hydroxyacetone, dihydroxyacetone, acetonitrile, aminopropionitrile, acrylonitrile, methylbutyronitrile, pentannitrile, and propionitrile, including those with isotopologues, acetic and acrylic acids, glycolaldehyde, and benzaldehyde, which can be regarded as potential markers of pathological tissue.