## 3 Results and Discussion
### Bio-Oil Analysis  
#### 3.4.1 Qualitative Results  
The produced liquids obtained during the experiments with the ESP and spray columns condensing systems have been qualitatively analyzed via GC-MS/FID. Figure 4 below presents the results from FC_SC2 as an example. In this case, three fractions were collected while operating the first condenser at a temperature of 170 \({}^{\circ}\)C and keeping the downstream devices, respectively, at a temperature of 70 \({}^{\circ}\)C and \(-10\) \({}^{\circ}\)C.  
Figure 3: Produced gas composition. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Peak Number** & **Detected Compound** & **RT-Retention Time (min)** \\ \hline \hline \multicolumn{3}{c}{First Fraction} \\ \hline
1 & Acetone & 4.6 \\
17 & Vanillin & 46.2 \\
18 & Lavoglucan & 54 \\ \hline \multicolumn{3}{c}{Second Fraction} \\ \hline
2 & Carbonic acid & 6.2 \\
4 & Acetic acid & 8 \\
5 & Butanal & 8.6 \\
7 & Butanediol & 15.3 \\
8 & 2-Cyclopenten-1-one & 22.30 \\
9 & 2H-Pyran-2-one & 26.70 \\
10 & Phenol & 28.40 \\
11 & P-Cresol & 30.65 \\
12 & o-Cresol & 32.40 \\
13 & Phenol, 3,5-dimethyl & 34.60 \\
14 & Phenol 3-ethil & 36.2 \\
15 & Phenol 2-ethyl-6-methyl & 38.3 \\
16 & 5-Me-(H)-Furan-2-one & 40 \\ \hline \end{tabular}
\end{table} 
Table 6: Components of bio-oil from fast pyrolysis of pinewood that were collected in the three fractions and detected by GC-MS/FID (FC_SC2). Figure 4: GC-MS/FID spectra for exp. FC_SC2 representative for compound distribution among the cuts: (**a**) First Fraction; (**b**) Second Fraction; (**c**) Aqueous Phase. Numbers in the plot relate to detected compounds, the reader is referred to Table 6 for interpretation. Components of bio-oil from fast pine wood pyrolysis and their relative retention time (RT) are shown in Table 6. While several other compounds have been detected during the analytical campaign of all the experiments, this can be considered to represent a fair display of the mean composition of the produced samples via these specific procedures. The overlying spectra of the bio-oil samples from the three condensers are shown in Figure 5, showing the peak distribution in the three bio-oil fractions. The first collector trapped most of the high molecular weight compounds (higher RT), while most of the light compounds were trapped in the final intensive cooler. The central trait (from 8 to 45 min of RT) was highly populated by several compound classes, which were concentrated in the second cut, including phenolics, cyclopentanones, methoxypnols, and furans. At a temperature of the first condenser of 170 \({}^{\circ}\)C, only long-chain anhydrous and lignin derivatives condensed because of their vapor pressure properties. Such behavior was confirmed over the entire range of tested temperatures. The levoglucosan concentration in the oil collected in the first condenser more than triples from 4 to 13 wt.% as the temperature in the first condenser was increased. Vapors leaving the first step and condensing into the second scrubber present a significant concentration of mid-boilers, mainly accounting for phenols, cyclopentenones, and some furans. In this section, the acid fraction was only 1.24 wt.%, coming from 6 wt.% at 100 \({}^{\circ}\)C. As for the final condensation step, light fractions are the compounds mostly present in the aqueous phase, showing a dependency on changes in the first step condensing temperature. For these operating conditions (170 \({}^{\circ}\)C), more than 90% of the acetic acid produced was recovered in the intensive cooler. Figure 5 can be considered an effective overview of how the process affects fluid composition and distribution. As other literature studies suggest [59; 60; 61; 62], both the oil and the aqueous phase contain several polar and non-polar compounds that can potentially be used as precursors for a multitude of bio-derived chemicals (e.g., commodity chemicals, polymers, agrochemicals, pharmaceuticals, etc.). However, further extraction and purifica