## 3 Experimental Results
Comparative analysis of the kinetic profiles obtained showed that phenol and octanal were always present at time zero in both healthy tissues and polypoid lesions. In addition, for these two VOCs, a gradual reduction over time was constantly observed until their \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \# & **RT (min)** & **Compound** & **Characteristic Ions (m/z)** & **Match** & **Prob. (\%)** & **Standard** & **Frequency (\%)** \\ \hline
15 & 10.22 \(\pm\) 0.09 & Pentanoic acid, ethylester & 57, 101 & 812 & 89.2 & & 0 & 3.1 \\ \hline
16 & 10.71 \(\pm\) 0.09 & Oxime, methoxy-phenyl & 133, 151 & 813 & 84.2 & & 68.8 & 96.9 \\ \hline
17 & 11.78 \(\pm\) 0.09 & Dimethyl trisulfide & 79, 126 & 849 & 96.9 & & 12.5. & 6.3 \\ \hline
18 & 11.93 \(\pm\) 0.09 & Benzaldehyde & 77, 106 & 930 & 92 & yes & 18.8 & 65.6 \\ \hline
19 & 12.12 \(\pm\) 0.09 & Phenol & 66, 94 & 984 & 88 & yes & 31.3 & 62.5 \\ \hline
20 & 12.29 \(\pm\) 0.08 & Octanal & 43, 56 & 888 & 60 & yes & 9.4 & 59.4 \\ \hline
21 & 12.52 \(\pm\) 0.08 & 1-Hexanol, 2-ethyl- & 57 & 829 & 13.0 & & 21.9 & 31.3 \\ \hline
22 & 12.74 \(\pm\) 0.09 & Isooctanol & 55, 112 & 800 & 20.3 & & 21.9 & 12.5 \\ \hline
23 & 13.47 \(\pm\) 0.09 & Nonanol & 57, 69 & 827 & 11.1 & yes & 25.0 & 25.0 \\ \hline
24 & 14.05 \(\pm\) 0.09 & Nonanal & 41 & & & yes & 3.1 & 3.1 \\ \hline
25 & 15.11 \(\pm\) 0.08 & Octanoic acid & 60, 144 & 781 & 30.9 & yes & 12.5 & 9.4 \\ \hline
26 & 15.31 \(\pm\) 0.08 & Decanal & 43, 138 & & & yes & 31.3 & 15.6 \\ \hline
27 & 15.63 \(\pm\) 0.08 & Dodecane & 43, 170 & 956 & 49 & yes & 25.0 & 9.4 \\ \hline
28 & 16.11 \(\pm\) 0.09 & Benzeneppropanol & 117, 136 & 909 & 60.0 & & 6.3 & 18.8 \\ \hline
29 & 16.61 \(\pm\) 0.09 & Triethanolamine & 118 & 900 & 67.0 & & 0 & 6.3 \\ \hline
30 & 16.86 \(\pm\) 0.09 & Undecano & 57, 156 & 908 & 44 & yes & 21.9 & 3.1 \\ \hline
31 & 17.07 \(\pm\) 0.08 & Indolo & 117 & 982 & 70 & yes & 40.6 & 62.5 \\ \hline
32 & 18.39 \(\pm\) 0.09 & Tetradecane & 57, 198 & 934 & 53 & yes & 25.0 & 12.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._  
Figure 2: Time-dependent monitoring (0, 1, 4, and 7 days) peak area of benzaldehyde, ethylbenzene, indole, methylbenzene, phenol, octanal, and oxime methoxy-phenyl by DI-SPME-GC-MS in tissue samples (normal colonic mucosa and adenomatous polyp) from the same patient (n\({}^{\circ}\) 2), before undergoing curative surgery. disappearance in all samples was analyzed. Oxime methoxy-phenyl also appeared in control samples, and its levels increased over time in all the cases. Benzaldehyde, ethylbenzene, indole, and methylbenzene were observed, for all samples, only after 24 h of incubation. Their levels, in general, increased progressively over the seven days but were significantly higher in adenomatous tissue than in healthy mucosa, whereas the opposite happens for ethylbenzene. Table 3 shows the linear regression analysis results and the concentration ranges, estimated in this study, for standardly identified VOCs (i.e., benzaldehyde, ethylbenzene, indole, methylbenzene, phenol, and octanal) in culture media containing tissues (normal colonic mucosa and adenomatous polyps). No standard was available for oxime methoxy-phenyl. The F-test results showed that only for the concentration levels of benzaldehyde, phenol, and octanal there was no statistically significant difference (\(p<0.05\)) between healthy mucosal and adenomatous polypoid lesion tissues. With reference to the exhaled breath, Figure 3 shows an example of the chromatogram of the same patient (n\({}^{\circ}\) 2; acquired in SCAN mode), before endoscopic treatment. Sixty-six VOCs were detected (S/N \(\geq\) 3) overall and sixty-one were identified and reported in Table 4. Benzaldehyde and methylbenzene, already evidenced in the colonic polyps and normal mucosa tissues, were also detected in the breaths of the same patients and, therefore, a possible correlation between their quantity in the breath and that released from tissues was hypothesized.