## 2 Materials and Methods
### Equipment Instrumental Analysis
#### 2.4.3 Gas Chromatography (GC)  
The P&T GC-MS analysis was carried out using a Finnigan Trace Gas Chromatograph Ultra with a Finnigan Trace DSQ mass detector from Thermo Scientific (Fremont, California, USA). The volatile compounds were separated on a Rxi-624 Sil MS (30 m \(\times\) 0.25 mm internal diameter, 1.40 um film thickness) column from Restek() (Bellefonte, PA, USA). The chromatographic conditions were as follows: helium was used as carrier gas at a constant flow rate of 1 mL/min; the oven program was initially set at 45 \({}^{\circ}\)C for 4 min, then increased at a rate of 8 \({}^{\circ}\)C/min until 250 \({}^{\circ}\)C and held for 5 min; the transfer line and source temperature were set at 250 \({}^{\circ}\)C and 200 \({}^{\circ}\)C, respectively. The mass spectra were obtained with a mass-selective detector operated under electron impact ionization mode at a voltage of 70 eV, and data acquisition was performed in full-scan mode over an \(m/z\) range of 20-500. For data acquisition and processing, Xcalibur 2.0.7 software was used. Compounds were identified using the commercial mass spectral libraries NIST/EPA/NIH 11 (version 2.0) and Wiley Registry(tm) 8 th edition.  
For the HS-SPME technique, an Agilent 6890 gas chromatograph equipped with an Agilent 5975B mass spectrometer (Agilent Technologies, Santa Clara, CA, USA) and a Combi-Pal autosampler (CTC Analytics, Zwingen, Switzerland) was used. The chromatographic capillary column was an HP-5 MS 5% phenyl methyl from Agilent (25 m \(\times\) 0.25 mm \(\times\) 0.25 \(\upmu\)m). The injection was performed in splitless mode, and helium was used as carrier gas at a constant flow rate of 1 mL/min. The oven program was initially set at 40 \({}^{\circ}\)C for 2 min, then increased at a rate of 9 \({}^{\circ}\)C/min until 300 \({}^{\circ}\)C and held for 10 min. The transfer line and source temperature were set at 320 \({}^{\circ}\)C and 230 \({}^{\circ}\)C, respectively. The chromatograms were acquired in full-scan mode over an \(m/z\) range of 20-500. Compounds were identify using the commercial mass spectral libraries NIST2014 and Wiley Registry(tm) 8 th edition.  
For the analysis of semi-volatile compounds, a Thermo Scientific Trace 1300 Series gas chromatograph with a Trace ISQ LT mass spectrometer detector and an AI1310 autosampler injector was used to carry out the GC analysis (Thermo Fischer Scientific, San Jose, CA, USA). The chromatographic conditions were as follows: an Rxi-5 Sil MS 5% diphenyl, 95% dimethyl polysiloxane (30 m \(\times\) 0.25 mm \(\times\) 0.25 \(\upmu\)m) column from Restek(r) (Bellefonte, PA, USA) was used; the injection port temperature was set at 300 \({}^{\circ}\)C. The injection mode was splitless, and the injection volume was 1.0 \(\upmu\)L. Helium was used as carrier gas at a constant flow rate of 1 mL/min. The transfer line and source temperature were set at 300 \({}^{\circ}\)C. The oven temperature program was the same as the one used for the analysis by HS-SPME. The chromatograms were acquired in full-scan mode over an \(m/z\) range of 35-500. The mass spectra were obtained with a mass-selective detector under electron impact ionization mode at a voltage of 70 eV. For data acquisition and processing, Xcalibur 3.0.63.3 software was used. Mass spectra libraries NIST/EPA/NIH 11 (version 2.0) and Wiley Registry(tm) 8 th edition were used for identification purposes.