## 3 Results and Discussion
### Comparison of the Essential Oils with the Hydrolate Volatiles  
The comparison of Tables 1 and 2 shows that essential oils and the hydrolate volatiles differed significantly. Hydrocarbon terpen as camphene, myrcene, \(\delta\)-3-carene, terpinolene, \(\alpha\)-humulene, and bicyclogermacrene could only be found in the distilled oils. \(\beta\)-Pinene was present in all essential oils, but could only be recovered in the hydrolate volatiles from KEM site. On the other hand, a range of oxidized monoterpenes occurred only in hydrolates; these were linalool, cis-p-menth-2-en-1-ol, trans-p-menth-2-en-1-ol, mentha-1,5-dien-8-ol, _trans_-carveol, and piperitone. Camphor, which could be detected in all hydrolate volatiles, was present only in a few essential oil samples at very low levels. The ratio of volatile percentages in hydrolate to distilled oil has been calculated for the compounds that occur in both sample types (Figure 5). Thus, terpene hydrocarbons having a ratio below one occurred mainly in the distilled oils, while oxidized compounds were more prominent in the respective hydrolate volatiles. In comparison to the essential oil, the hydrolate volatiles had a 158-, 186-, or 303-times higher percentage for the oxidized monoterpenes terpinen-4-ol, \(\alpha\)-terpineol, and verbenone, respectively. Figure 4: PCA scoring plot showing the hydrolate volatile samples from the individual _P. cembra_ trees. Figure 3: Hydrolate volatile compounds loading on the first two axes of a principal component analysis of _P. cembra_ hydrolates. The fact that hydrolate volatiles are low in hydrocarbons and higher in oxygenized compounds has been reported for hydrolates from various plants. The essential oils from _Abies alba_ and _A. koreana_ cones and seeds is constituted by 82.4-93.4% monoterpene hydrocarbons, mainly \(\alpha\)-pinene and limonene, and in contrast the volatiles in the respective hydrolates were composed of 83.1-94.4% of oxidized monoterpenes [23]. While _Picaa glauca_ essential oil contained 20% \(\beta\)-pinene and 12% \(\alpha\)-pinene, these constituents were barely present in the hydrolates [24, 25]. A _Solidago puberula_ essential oil had 37.2% \(\alpha\)-pinene and the respective hydrate was devoid of it [25]. Similarly, myrcene and \(\beta\)-phellandrene, accounting together for 72-74% of the essential from _Anthriscus sylvestris_, occurred from traces to 1.6% in the hydrolate volatiles [26]. This distribution is, to a large extent, due to the low solubility of hydrocarbons in water; for monoterpene hydrocarbons such as \(\alpha\)-pinene, \(\beta\)-pinene, camphene, myrcene, and \(\alpha\)-phellandrene, the solubility is below 10 mg/L at 25 \({}^{\circ}\)C. The water solubility of \(\alpha\)-terpineol and erpinene-4-ol is reported to be 7100 and 387 mg/L, respectively [27]. Additionally, the enrichment of oxidized compounds in the hydrolates is documented. The distilled oils from _Myrica gale_ contained none to 0.2% \(\alpha\)-terpineol, and none to 0.4% teripen-4-ol, while the hydrolate volatiles accumulated these compounds to 11.3-15.6% and 13.4-14.3%, respectively [28]. In the case of _Teucrium kabylicum_, a percentage of 0.4% teripen-4-ol was found in the essential oil, and of 23.2% in the hydrolate volatile fraction [29]. The partition of a compound between the essential oil and the water phase of the hydrolate also depends on the solubility of the oil compound in the essential oil itself. _P. cembra_ essential oil is composed of more than 90% terpene hydrocarbons, a very apolar matrix. This is a less favorable environment for oxygenated compounds, supporting their transfer into the water phase. Therefore, we obtained higher ratios (Figure 5) between hydrate and essential oil for these compounds than those reported in the literature. For example, in the present study, camphor occurred up to 2.7% in the hydrolate volatiles, while in distilled oil it could only be found in traces (<0.05%).