## 2 Results and Discussion
### Headspace, Volatile, and Semi-Volatile Organic Compounds
That could be the consequence of its low molecular mass and high volatility. However, another DMSP breakdown product, dimethylsulfoxide (1.52%; 2.63%), appeared only in HS-D. On the other hand, the percentage of heptadecane raised in HS-D up to 52.62% (Table 1) presumably as the consequence of DMS loss. In addition, several other saturated hydrocarbons appeared in HS-D (Table 1) with minor percentages (e.g., pentadecane, hexadecane, octadecane or nonadecane) as well as two unsaturated alkenes ((\(E\))-heptadec-8-ene and nonadec-1-ene). Carotenoid cleavage products, C\({}_{13}\)-norisoprenoids (that could arise enzymatically [38] or non-enzymatically [39] stimulated by light, oxygen, temperature, and acid hydrolysis), were found only in HS-D: (\(E\))-\(\alpha\)-ionone (6.40%; 3.02%), (\(E\))-\(\beta\)-ionone (1.52%; 1.02%,) and 4-ketoisophorone (0.10%; 0.10%). In addition, other oxygenated aliphatic compounds were found in HS-D (Table 1), such as: hexan-1-ol, octan-2,3-dione, 6-methylhept-5-en-2-one, 2-ethylhept-5-en-2-one or (\(E\))-oct-2-enal. The distillate of fresh _C. bursa_ (HD-F) contained as the major compounds higher saturated aliphatic hydrocarbons heptadecane (23.44%) and docosane (13.90%) (Table 1). Higher heptadecane abundance was expected according to HS-SPME results. Docosane was identified previously in _C. fragile_ after steam distillation of the dichloromethane extract [40] and with minor percentages (1.14%) in _C. fragile_ essential oil [15]. Hydrocarbons dominated [15] in the essential oil isolated from freeze-dried samples of _C. fragile_, such as tricosane (11.88%), 2,2,4-trimethyl-1,3-dioxolane, (8.53%), hexadecane (4.07%), eicosane (3.83%), and tetracosane (3.48%). Other abundant compounds (Table 1) were disloocotyl phtalate (13.30%) and dibutyl phtalate (9.80%). It has been shown by analyzing the natural abundance 14C content of the isolated compounds and industrial products that dialkyl phthalates can be naturally produced by algae [41]. (\(E\))-Phydu was identified in the essential oil with 3.31% along with its derivative phytone (1.61%). The presence of linear diterpene alcohol _trans_-phytol and its acetate derivatives were previously reported in the extract of _C. fragile_[8]. After air-drying _C. bursa_, \(a\) significantly different chemical composition of the volatile oil was obtained (HD-D). Namely, (\(E\))-phytol predominated (58.42%), and its percentage raised ca. 17.7 times in comparison to HD-F, probably as the consequence of chlorophyll breakdown [42] and _trans_-phytolwas also found in the extract of _C. fragile_[8]. In addition, the percentage of phytone raised ca. 3.5 times compared to the fresh sample. Oxidation of phytol moiety of chlorophyll could lead, among others, to the methylated long chain fatty acid ketone-hexahhydroxyfarnesyl acetone (6,10,14-trimethylpentadecan-2-one, phytone) that was found in the oil from the dried sample at 5.91%. Another significant change in HD-D was a significant decrease (9.8 times for dibutyl phthalate) or disappearance (diisooctyl phthalate) of alkyl phthalates (Table 1). Benzyl alcohol percentage also dropped from 18.02% to 0.10% which is probably due to its evaporation. The major compound of SC-CO\({}_{2}\) extract of FD-CB was (_E_)-phytol (42.30%) accompanied by structurally related neophytadiene (3.20%). Other dominant aliphatic compounds were hexadecanoic acid (17.51%), heptadecane (7.20%), hexadecan-1-ol (3.10%), and (_Z_)-octadec-9-enoic acid (3.02%). The composition of SC-CO\({}_{2}\) extract was partially similar to HD-D (Table 1, VI, and VII). However, monoterenoid hydroxylactone lioliolide (3.51%) was only identified in SC-CO\({}_{2}\) extract. Among green algae, it was found previously in _Codium divaricatum_ [PERSON] from which it was isolated by ethanol extraction from dried algae [43].