## 2 Materials and Methods  
### Chemical Standards, Materials, and Samples  
Acetonitrile (ACN, 99.9%), \(n\)-hexane (\(n\)-C\({}_{6}\), 96.0%), dichloromethane (DCM, 99.9%), and \(n\)-heptane (\(n\)-C\({}_{7}\), 99.0%), all of HPLC-grade, were obtained from Carlo Erba (Val-de-Reuil, France). Methanol (MeOH, 99.9%), also of HPLC-grade, and isooctane (for analysis) were obtained from Honeywell (Issy-les-Moulineaux, France). (+) -\(\alpha\)-pinene (98.0%, USA), (-) -\(\beta\)-pinene (99.0%, USA), 1,8-cineole (99%, USA), R-(+) -limonene (97.0%, Mexico) and bromopentafluorobenzene (99.0%, UK), used as internal standard (IS), were purchased from Sigma-Aldrich (St. Louis, MO, USA). Thymol and (-) carryophyllene oxide (99%, Germany) were acquired from Sigma-Aldrich and Jose M. Vaz Pereira, Lda. (Lisbon, Portugal), respectively. A standard mixture of \(n\)-alkanes C\({}_{7}\)-C\({}_{30}\) (50.0 mg/L of each in \(n\)-C\({}_{7}\)), of HPLC and GC-grade was obtained from Sigma-Aldrich. Ultra-pure water was obtained from a Milli-Q water purification system from Merck (Millipore, Burlington, MA, USA). For the HS-BA\(\mu\)E assays, the sorbent coatings tested included reverse phase polymers such as \(N\)-vinylpyrrolidone Strata\({}^{\text{TM}}\) X (S-X; pore size: 85 A, particle size: 33 \(\upmu\)m, surface area: 800 m\({}^{2}\)/g), styrene-divinylbenzene co-polymer Strata\({}^{\text{\textregistered}}\) SDB-L (S-DVB; pore size: 280 A, particle size: 100 \(\upmu\)m, surface area: 500 m\({}^{2}\)/g), and the ciano-based co-polymerStrata(r) CN (S-CN; pore size: 70 A, particle size: 55 \(\upmu\)m, surface area: 500 m\({}^{2}\)/g) obtained from Phenomenex (Torrance, CA, USA), as well as \(N\)-vinylpyrrolidone-divinylbenzene co-polymer Oasis(r) HLB (HLB; pore size: 80 A, particle size: 30 \(\upmu\)m, surface area: 800 m\({}^{2}\)/g) obtained from Waters (Milford, MA, USA). The commercial ACs tested included CA1 (pHPZC 2.2, surface area: 1043 m\({}^{2}\)/g, V\({}_{\text{ mesopopores}}\): 0.66 cm\({}^{3}\)/g, V\({}_{\text{$\alpha$-supermicropores}}\): 0.26 cm\({}^{3}\)/g), CN1 (pHPZC 5.1, surface area: 1179 m\({}^{2}\)/g, V\({}_{\text{ mesopospores}}\): 0.68 cm\({}^{3}\)/g, V\({}_{\text{$\alpha$-supermicropores}}\): 0.3 cm\({}^{3}\)/g), and SX PLUS (pHPZC 8.4, surface area: 833 m\({}^{2}\)/g, V\({}_{\text{mesopores}}\): 0.44 cm\({}^{3}\)/g, V\({}_{\text{$\alpha$-supermicropores}}\): 0.15 cm\({}^{3}\)/g, V\({}_{\text{$\alpha$-ultmicropores}}\): 0.08 cm\({}^{3}\)/g) obtained from Salmon & Cia (Lisboa, Portugal) and the R (pHPZC 6.5, surface area: 964 m\({}^{2}\)/g, V\({}_{\text{ mesopopores}}\): 0.40 cm\({}^{3}\)/g, V\({}_{\text{$\alpha$-supermicropores}}\): 0.16 cm\({}^{3}\)/g, V\({}_{\text{$\alpha$-ultmicropores}}\): 0.09 cm\({}^{3}\)/g) obtained from Riedel-de Haen (Hannover, Germany). For the HS-SPME assays, a manual holder and polydimethylsiloxane/divinylbenzene (PDMS/DVB, 65 \(\upmu\)m) fibers were used, both purchased from Supelco(r) (Bellefonte, PA, USA). The leaves from all shrub species were sampled only once; the _Cistus_, _Erica_, and _Thymus villosus_ L. were sampled on 17 April 2023 at Parque Natural de Sintra-Cascais, and _Thymus camphoratus_ was sampled on 6 May 2023 at Ribeira da Azenha-Vila Nova de Milfontes (37\({}^{\circ}\)48\({}^{\prime}\)17.6\({}^{\prime\prime}\) N 8\({}^{\circ}\)46\({}^{\prime}\)58.4\({}^{\prime\prime}\) W). _Cistus lamalifer_ L. and _Cistus nonspeliensis_ L. were sampled at Abano (38\({}^{\circ}\)44\({}^{\prime}\)26.16\({}^{\prime\prime}\) N 09\({}^{\circ}\)28\({}^{\prime}\)10.10\({}^{\prime\prime}\) W), _Lavandula stoechas_ L. and _Erica scoparia_ L. at Biscaa (38\({}^{\circ}\)45\({}^{\prime}\)45.84\({}^{\prime\prime}\) N 09\({}^{\circ}\)28\({}^{\prime}\)30.68\({}^{\prime\prime}\) W), and _Thymus villosus_ L. at Pedra Amarela (38\({}^{\circ}\)45\({}^{\prime}\)30.11\({}^{\prime\prime}\) N 09\({}^{\circ}\)26\({}^{\prime}\)01.94\({}^{\prime\prime}\) W). The collected fresh leaves were stored in sealed flasks in a thermal box and, upon arrival at the laboratory, were stored in the fridge until analysis.