## 3 Results & Discussion
### HS-SPME-GC-MS--Headspace Solid-Phase Microextraction Coupled to Gas Chromatography
#### 3.3.2 Validation method
Concerning octanal behaviour, the initial concentration was lower in PHB 226 but for this matrix, it seems that all organoclays provoke increases in the release of this volatile instead of retaining them. On the contrary, T3 prevents the release of octanal in PHA 1005 decreasing its release in a remarkable 92%. However, for PHA 3002, it seems that T2 suits better as it hinders the release of this volatile compound more efficiently than T3, 66%. PHB 226 showed the highest decanal initial content. T2 was the most effective clay reducing the release of this compound in a 43%. T2 nanoclay was also the most efficient for the PHA 1005 matrix although there was no decrease for any of the three organoclays. The same tendency was found for PHA 3002, being in this case T3 the nanoclay increasing the release to a lesser extent. Regarding \(\alpha\)-methylstyrene, the lowest content was determined in PHB 226 and PHA1005 at equal rates by decreasing its release in 75%. For this compound and in particular for PHA 3002_T3 the developed formulation seems to be especially effective since it was not possible to detect the presence of this volatile compound therein. Finally, Benzaldehyde was initially present in a similar quantity in all formulations. In this case, T2 could be more effective in PHB 226 and PHA 1005 matrices whereas for PHA 3002 no significant effect was observed. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Volatile Compound**} \\ \cline{2-13}  & \multicolumn{2}{c}{**1-Hexanol**} & \multicolumn{2}{c}{**Hepunal**} & \multicolumn{2}{c}{**Octual**} & \multicolumn{2}{c}{**Deconal**} & \multicolumn{2}{c}{**\(\alpha\)-Methylstyrene**} & \multicolumn{2}{c}{**Benzaldehyde**} \\ \cline{2-13}
**Sample Material** & \multicolumn{2}{c}{**Average**} & \multicolumn{2}{c}{**SD**} & \multicolumn{2}{c}{**Average**} & \multicolumn{2}{c}{**SD**} & \multicolumn{2}{c}{**Average**} & \multicolumn{2}{c}{**SD**} & \multicolumn{2}{c}{**Average**} & \multicolumn{2}{c}{**SD**} & \multicolumn{2}{c}{**Average**} & \multicolumn{2}{c}{**SD**} \\ \cline{2-13}  & **(ug/g sample)** & **SD** & **(ug/g sample)** & **SD** & **(ug/g sample)** & **SD** & **(ug/g sample)** & **SD** & **(ug/g sample)** & **SD** \\ \hline PHA 1005 & 18.8 & 3.8 & 14.8 & 6.8 & 68.6 & 14.9 & 900 & 500 & 102.8 & 35.4 & 6.4 & 0.3 \\ PHA 1005\_T1 & 13.2 & 1.1 & 15.8 & 1.5 & 68.1 & 7.1 & 2100 & 500 & 283.6 & 12.2 & 5.7 & 1.2 \\ PHA 1005\_T2 & 8.2 & 1.3 & 15.3 & 3.2 & 78.1 & 13.9 & 1300 & 200 & 25.7 & 10.0 & 4.3 & 0.3 \\ PHA 1005\_T3 & 5.3 & 0.7 & 81.2 & 29.3 & 5.3 & 0.7 & 5300 & 700 & 89.6 & 33.5 & 5.3 & 0.7 \\ \hline PHA 3002 & 2.7 & 1.0 & 18.8 & 10.0 & 75.4 & 18.8 & 1000 & 300 & 135.4 & 28.4 & 4.5 & 1.5 \\ PHA 3002\_T1 & 2.8 & 1.0 & 27.9 & 1.7 & 41.2 & 6.5 & 3000 & 500 & 279.5 & 17.6 & 7.1 & 0.3 \\ PHA 3002\_T2 & 16.6 & 2.9 & 41.4 & 16.3 & 25.3 & 7.4 & 2400 & 400 & 59.3 & 11.6 & 4.6 & 0.7 \\ PHA 3002\_T3 & 8.1 & 2.7 & 98.8 & 11.1 & 53.6 & 16.8 & 1800 & 400 & nd & nd & 6.7 & 1.1 \\ \hline PHB 226 & 3.7 & 0.9 & 4.0 & 0.6 & 26.7 & 0.5 & 2300 & 100 & 40.4 & 4.6 & 7.7 & 0.7 \\ PHB 226\_T1 & 1.2 & 0.9 & 3.2 & 1.1 & 32.6 & 6.0 & 1900 & 200 & 43.4 & 7.1 & 7.2 & 2.6 \\ PHB 226\_T2 & 2.3 & 0.6 & 10.3 & 0.9 & 39.3 & _7.7_ & 1300 & 300 & 10.3 & 2.3 & 4.9 & 0.5 \\ PHB 226\_T3 & 1.6 & 0.6 & 3.5 & 7.6 & 71.3 & 17.9 & 2800 & 700 & 39.6 & 17.3 & 6.5 & 2.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Volatile compounds content for the PHB 226 PHA 1005 and PHA 3002 controls and the T1, T2 and T3 formulations, expressed as the mean \(\pm\) SD (n = 3). Figure 5: Percentage variation of volatile substances in the samples of study: (**a**) PHA1005, (**b**) PHA3002, (**c**) PHB26.