## 4 Conclusions  
The novel electrospun composite nanofibers of PET superhydrophobic nano-SiO\({}_{2}\) were fabricated and used as effective fiber coating in HS-SPME. The novel nono fiber was applied for SME extraction of 16 organochlorine pesticides from water samples and \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Compound**} & \multirow{2}{*}{**LOD \({}^{\star}\)**} & \multirow{2}{*}{**LOD \({}^{\star}\)**} & \multirow{2}{*}{**R2**} & \multicolumn{4}{c}{**RSD \({}^{\star}\)**} & \multicolumn{4}{c}{**RSD \({}^{\star}\)**} \\ \cline{6-13}  & & & & & & & & & & & & & \\ \hline \(\alpha\)-HCH & 30 & 80 & 80–10,000 & 0.9967 & 6.3 & 8.6 & 7.5 & 2.2 & 6.4 & 5.4 \\ \(\beta\)-HCH & 20 & 50 & 50–5000 & 0.9914 & 5.3 & 1.7 & 3.5 & 3.1 & 2.4 & 2.4 \\ \(\gamma\)-HCH & 20 & 50 & 50–5000 & 0.9914 & 4.8 & 9.5 & 7.1 & 3.2 & 7.0 & 6.3 \\ \(\delta\)-HCH & 80 & 200 & 200–10,000 & 0.9983 & 8.1 & 10.6 & 4.8 & 8.2 & 8.8 & 11.9 \\ Heptachlor & 20 & 50 & 50–5000 & 0.9907 & 10.5 & 7.3 & 8.9 & 5.5 & 6.0 & 6.4 \\ Aldrin & 3 & 8 & 8–2000 & 0.9977 & 6.2 & 4.5 & 5.4 & 4.0 & 3.9 & 4.2 \\ Heptachlor & 3 & 8 & 8–2000 & 0.9930 & 5.5 & 2.6 & 4.0 & 5.5 & 2.7 & 4.0 \\ eposulfan 1 & 80 & 200 & 200–10,000 & 0.9987 & 10.9 & 10.3 & 11.6 & 5.7 & 10.6 & 12.0 \\ p\(\
u\)-PDE & 3 & 8 & 8–2000 & 0.9989 & 7.2 & 6.5 & 6.8 & 2.6 & 4.2 & 4.5 \\ Dieldrin & 30 & 80 & 80–5000 & 0.9909 & 11.3 & 7.6 & 11.5 & 4.2 & 6.0 & 5.9 \\ Endrin & 30 & 80 & 80–5000 & 0.9987 & 9.8 & 3.1 & 6.5 & 1.7 & 3.4 & 2.4 \\ Endosulfan II & 30 & 80 & 80–5000 & 0.9932 & 12.3 & 8.1 & 10.2 & 5.6 & 4.3 & 6.9 \\ p\(\
u\)-DDD & 30 & 80 & 80–2000 & 0.9912 & 12.4 & 8.5 & 5.4 & 10.0 & 8.8 & 9.3 \\ Endrin & 30 & 80 & 80–2000 & 0.9942 & 13.8 & 8.0 & 5.4 & 9.5 & 11.0 & 12.3 \\ Endosulfan & 30 & 80 & 80–5000 & 0.9921 & 11.4 & 9.3 & 7.3 & 8.5 & 6.6 & 11.4 \\ p\(\
u\)-DDT & 30 & 80 & 80–5000 & 0.9965 & 11.3 & 10.5 & 11.4 & 11.3 & 11.8 & 13.4 \\ \hline \hline \end{tabular}  
* Limit of detection (ng L\({}^{-1}\)). \({}^{\mathrm{b}}\) Limit of quantification (ng L\({}^{-1}\)). \({}^{\mathrm{c}}\) Linear dynamic range (ng L\({}^{-1}\)). \({}^{\mathrm{d}}\) C = 400 ng L\({}^{-1}\). \({}^{\mathrm{e}}\) C = 1000 ng L\({}^{-1}\).  
\end{table} 
Table 1: Analytical data obtained by HS-SPME of OCPs mixture using the PET/nano-SiO\({}_{2}\) adsorbent. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Methods**} & \multirow{2}{*}{**Sorbent**} & \multirow{2}{*}{**LOD \({}^{\star}\)**} & \multirow{2}{*}{**LDR \({}^{\mathrm{b}}\)**} & \multicolumn{4}{c}{**Extraction**} \\  & & & & & & & & & & & & & & & \\ \hline SPME & PET/NanoSiO\({}_{2}\) & 3–80 & 8–10,000 & 10 & 78–120 & Current study \\ SPE-GC/ECD & Florisi & 400–2000 & 5–1000 & - & 77–105 & [33] \\ SMPE & PDMS \({}^{\mathrm{d}}\)/PA \({}^{\mathrm{e}}\) & 20–80 & 50–1000 & 20 & 91.4 (average) & [34] \\ SB-\(\mu\)-SPE & Hydrooxide/graphene & 300–1400 & 1000–200,000 & 20 & 84–2–100.2 & [8] \\ ASE \({}^{\mathrm{f}}\) \& SPME & PDMS/PA & 0.2–4.9 (ng m\({}^{-3}\)) & 50–3000 (ng m\({}^{-3}\)) & 40 & - & [35] \\ \hline \hline \end{tabular}  
* Limit of detection (ng L\({}^{-1}\)). \({}^{\mathrm{b}}\) Linear dynamic range (ng L\({}^{-1}\)). \({}^{\mathrm{c}}\) Relative Recovery. \({}^{\mathrm{d}}\) Polydimethylsiloxane.
* Polyacrylamide. \({}^{\mathrm{f}}\) Accelerated solvent extraction.  
\end{table} 
Table 3: Comparison of HS-SPME/GC-ECD with other published method for determination of OCPs. thermally desorbed and analysed with GC-\(\mu\)ECD. After characterization, the large specific surface area, the porous structure of the adsorbent were obtained. Based on this, the adsorbent and the analytes led to a fast equilibrium (10 min) and efficient extraction with recovery \(>\) 90%. Moreover, the low limit of detection (3-80 ng L\({}^{-1}\)) and good linearity (8-1000 ng L\({}^{-1}\)) are the characteristics that provide an excellent sensitivity of the OCPs analytes.