## 3 Discussion
Our results also indicate that this method could be more suitable for irone detection than HD, considering that the samples extracted by HS-SPME contained almost double the amounts of irones compared to the ones extracted by the previous method, with the relative contents varying between 43.74% and 45.76% for _cis-_\(\alpha\)-irone. However, the fibers used in the present study were not suitable for the extraction of long-chain fatty acids, which are the known major characteristic constituents of _Iris_ EOs. Conversely, short-to-medium-chain (volatile) fatty acids such as acetic, caproic, and caprylic were found in these samples, with the major one being acetic acid (1.91-31.02%), which was not present in the irone-rich sample of _1. pseudopallida_. Short-chain fatty acids, including acetic and caproic acids, are important for different industries, including the pharmacy, cosmetic, and perfume industry [51]. However, these compounds were not detected in the EOs obtained by HD. The loss of volatile compounds and oxidative degradation are some of the possible drawbacks of HD [40]. With this in mind, HS-SPME may be more suitable for terpene extraction from the samples. For example, limonene, a monoterpene hydrocarbon which was found to be a major VOC characteristic of _1. adriatica_ after using HS-SPME (and was also present in other samples), was not detected in the same taxon after HD. It can be observed from the obtained results that different conclusions could be gained about the studied samples depending on the method of choice being either HD or HS-SPME. This highlights the importance of combining different extraction methods in the analyses and comparison of VOCs from rhizomes of different _Iris_ taxa. Different fiber coatings extract analytes from samples by either absorption (liquid coatings) or adsorption (solid coatings). The polar polyacrylate (PA) and non-polar single-phase polydimethylsiloxane (PDMS) fibers are included in the category of coatings based on absorption. The adsorption mechanism is used by mixed-phase bipolar fibers, such as PDMS/DVB, Carbowax(r)/divinylbenzene (CW/DVB), CAR/PDMS, and DVB/CAR/PDMS [52]. According to several studies, bipolar fiber coatings have the ability to extract a greater range of compounds than single coatings [53; 54; 55]. The DVB/CAR/PDMS and PDMS/DVB fibers, which have been demonstrated to be most appropriate for untargeted HS-SPME analysis of volatiles [32], were used in this study to analyze the VOCs of _1. pseudopallida, I. illlyrica_, and _1. adriatica_. In our study, comparable VOC profiles, in contrast to HD, were obtained using the said fibers, PDMS/DVB and DVB/CAR/PDMS, as previously reported [32]. However, more headspace VOCs were extracted using PDMS/DVB fiber (77) than using DVB/CAR/PDMS fiber (71), which is in accordance with the results reported by [PERSON] et al. [56], who explored _Eugenia lotzschiana_ O. [PERSON] fruit pulp and extracted 23 VOCs from PDMS/DVB fiber, 17 from PA fiber, and only 8 from DVB/CAR/PDMS fiber. When compared to each other, PDMS/DVB fiber extracted more monoterpene hydrocarbons, oxygenated monoterpene, and sesquiterpene hydrocarbons, while DVB/CAR/PDMS extracted more fatty acids and related esters. Similarly, in our recent investigation of _Sideritis romana_ L. and _S. montana_ L. VOCs, it was also observed that PDMS/DVB fiber may extract more sesquiterpene hydrocarbons and oxygenated sesquiterpenes, and DVB/CAR/PDMS fiber extracted more oxygenated monoterpene and other compounds (mostly non-terpenes) [57]. The affinity of a fiber for a particular VOC depends on the principle of \"like dissolves like\", where PDMS/DVB fiber is more polar than the DVB/CAR/PDMS fiber and preferred for the extraction of analytes with higher molecular weights (MW 50-300) [32; 58].