## 2 Results and Discussion
### GC-MS Analysis of the Volatile Compounds Obtained Using \(Hd\) and HS-SPME
dulcia citreus_ Hillary's Sweet Lemon (**M5**) by [PERSON] [18]. Pulegone and menthofuran, which may have hepatotoxic effects, are found not only in _M. pulgeium_ but also in smaller amounts in other taxa of the genus _Mentha_[19]. The European Medicines Agency, in a public statement on the use of herbal medicinal products containing pulgeone and menthofuran, described the toxicity of this compounds and recommended limit values for herbal medicinal products that contain them [20]. According to the toxicological conclusions of the EMA's statement, the target organs for pulgeone and menthofuran are the liver and kidney. Several chemotypes of _M. longifolia_ can be distinguished including the piperitone-dominated chemotype [21; 22]. Piperientone (38.92%), piperitone oxide (32.88%) and _cis_-piperitone oxide (21.05%) were present in the highest amounts in _M. longifolia_ var. _schimperi_ (**M6**), while, in the EO from _M. longifolia_ (**M7**), only piperitone oxide was detected as the predominant compound (84.66%). Other studies identified pulgeone as the major EO compound from this taxon, as well as isomenthone or carvone [23; 24; 25; 26]. Menthofuran was not detected in any analyzed Eos obtained by HD, while pulgeone was detected only in _M. \(\times\) piperita_ var. _officialis_ f. _pallescens_ [PERSON] 'Swiss' (**M1**) (0.62%). In this taxon, pulgeone (2.14%) was also identified by [PERSON] et al. [17]. The EO from the leaves of _M. longifolia_ was characterized by pulgeone as the main component by [PERSON] et al. [27]. Thymol, 1,8-cineole (syn. eucalypt), and limonene are very often used in the food and cosmetic industries because of their characteristic organoleptic properties. However, they also show various pharmacological properties: mucolytic, antibacterial, antiviral, antifungal, and anti-biofilm [28; 29; 30]. Thymol is one of the main constituents of the essential oils of the genus _Thymus_; however, it can also be found in small amounts in the genus _Mentha_[31; 32; 33; 34]. In all taxa except _M. longifolia_ var. _schimperi_ (**M6**), 1,8 cineole was present. Limonene was detected in _M. \(\times\) piperita_ var. _citrata_ 'Grapefruit' (**M2**) at the level 9.11%, _M. dulcia citreus_ Hillary's Sweet Lemon (**M5**) at 6.89%, _M. \(\times\) carinthiaca_ (**M4**) at 5.64%, _M. \(\times\) piperita_ var. _citrata_ (**M3**) at 1%, and _M. longifolia_ var. _schimperi_ (**M6**) at 0.34%. The highest amount of thymol in analyzed samples was present in _M. \(\times\) piperita_ var. _citrata_ (**M3**), at 7.04%. The results of the GC-MS analysis of the volatile fractions obtained using HS-SPME are presented in Table 2. HS-SPME parameters were optimized with respect to the overall number of identified compounds. The standard deviation achieved was \(<\)10% for triplicate measurements. To the best of our knowledge, VOCs of taxa **M1-M5** and **M7** were investigated for the first time using the HS-SPME technique. [PERSON]'s study showed that piperitone oxide was found to be predominant among VOCs of _M. longifolia_ (**M7**) leaves, which was also confirmed by the performed analysis [35]. [PERSON] et al. identified pulgeone as the major component of VOCs obtained using the HS-SPME method from this taxon [23]. Comparing GC-MS results of mints VOCs obtained using HD and HS-SPME, it was found that their main components were the same, and they differed only in their abundance. Some smaller variations were observed in the profile of the constituents. Menthofuran (7.27%) and a higher amount of pulgeone (3.67%) compared with HD were observed only in _M. \(\times\) piperita_ var. _officialis_ f. _pallescens_ [PERSON] 'Swiss' (**M1**). The concentrations of \(\alpha\)-pinene, sabinene, \(\beta\)-pinene, and \(\beta\)-myrcene were lower in the samples from the mint _M. \(\times\) piperita_ var. _officialis_ f. _pallescens_ [PERSON] 'Swiss' (**M1**), _M. \(\times\) piperita_ var. _citrata_ 'Grapefruit' (**M2**), _M. \(\times\) piperita_ var. _citrata_ (**M3**), _M. \(\times\) carinthiaca_ (**M4**), and _M.