## 4 Discussion  
It is known from the literature [19] that the destruction of some amino acids when heated to temperatures above 200 \({}^{\circ}\)C is characterized by decarboxylation and deamination reactions. As a result of heating, unsaturated hydrocarbons are formed, the structure of which corresponds to that of amino acids. For example, the thermal decomposition of \(\alpha\)-Alanine, \(\beta\)-Alanine, \(\alpha\)-Valine, \(\alpha\)-Leucine, and \(\alpha\)-Isoleucine is accompanied by the appearance of ammonia, carbon dioxide, and carbon monoxide in the thermal decomposition products of all these acids. The other compounds recorded for these five amino acids on such heating are different. In addition to the above-mentioned compounds, for example, \(\alpha\)-Alanine decomposes into ethane, ethene, propene, butene-2, acetaldehyde, ethylamine, \(N\)-ethylideneethylamine, 2-methyl-5-ethylpyridine, and \(N\)-ethylpropionamide, whereas \(\beta\)-Alanine decomposes into ethene, propene, acetonitrile, acetone, pyridine, 3-picoline, 2,4-Puthidine, 3,5-dimethylpyridine, and 2,3,5-trimethylpyridine [19]. Some compounds that can appear during amino acid decomposition (for example, ethane, ethene, propane, and some others) are non-polar (i.e., have a zero dipole moment); therefore, they cannot be registered by nonstationary THz gas spectroscopy. The chemical compounds with a non-zero dipole moment can be detected by their spectra. Based on the analysis of data in the literature and the comparison of substances obtained during the study of urine samples, it can be assumed that heating of some amino acids that enter the composition of proteins, possibly including PSA, may be accompanied by the appearance of nitriles in thermal decomposition products. As has been noted above, the appearance of nitriles (acetonitrile, butyronitrile, pentanitrile, pentanedienitrile, benzonitrile, aminoproponitrile) in the urine of prostate cancer patients can be caused by thermal decomposition of amino  
Figure 4: Recording of a section of a spectrum with the absorption line of formic acid (HCOOH) \(f_{\text{exp}}=133.7675\) GHz (\(f_{\text{cat}}=133.76707\) GHz lg I = \(-3.8331\) 6 0 6 \(\leftarrow\) 5 0 5 [17]) in urine thermal decomposition products from a sample from a prostate cancer patient and the carbonyl sulfide line \(f_{\text{exp}}=133.7859\) GHz (\(f_{\text{cat}}=133.7859\) GHz lg I = \(-3.2369\) 11 \(\leftarrow\) 10 [18]) in thermal decomposition products of urine in sample 16 from a prostate cancer patient (red) and in sample 1.1 from a conditionally healthy volunteer (blue).  
acids including PSA amino acids. The emergence of sulfur-containing compounds, such as sulfur dioxide, hydrogen sulfide, and methyl mercaptan, may be due to the thermal decomposition of sulfur-containing amino acids (methionine, cysteine, cystine), which may also be associated with the thermal decomposition of proteins in urine. In addition, when denatured, PSA consisting of a large number of amino acids (with disulfide bridges) can also give rise to sulfur-containing compounds. At the same time, some light amino acids (for example, alanine) appear in the products of thermal decomposition of urine.  
The resulting list of substances and the differences in the composition of substances identified for patients with prostate cancer and conditionally healthy volunteers, given the accumulation of data, allow conclusions to be drawn about significant substances appearing in urine heated to obtain a gas mixture with respect to prostate cancer. In future, a comparison can be made with the products of thermal decomposition of amino acids, which make up PSA, which increases in urine in prostate cancer patients. This will make it possible to use the identified markers among the thermal decomposition products of urine to create chemical sensors for specific substances, which can be used to diagnose prostate cancer.