## 4 Conclusions  
In this work, a straightforward, solvent-free, and relatively rapid analytical methodology based on DI-SPME followed by GC-MS was developed, optimized, and validated to determine pesticide residues in water samples. The microextraction procedure was based on SPME devices fabricated with common commercial stainless-steel needles, which were internally coated with silicone sealant. Although the preparation was simple, rapid, and used low-cost materials, the obtained SPME needles proved to be stable, reusable, efficient, and robust, compared with commercial devices that are based on fragile fused silica fibers. Moreover, PDMS is a hydrophobic sorbent, but the proposed preparation technique could be applied to more polar polymers or composites. The developed analytical method was selective, sensitive, precise, and linear over a wide range of concentrations for the determination of pesticide residues in aqueous media. The investigated pesticides were from different chemical groups (organophosphates, organochlorines, pyrethroids, carbamates,  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**N** & **Pesticides** & **M.W** & **SIM Ions** & **RT (min)** \\ \hline
**1** & Diazinon & 304 & 137, 179, 152 & 15.790 \\
**2** & Chloropyriphos-methyl & 321 & 286, 288, 125 & 16.926 \\
**3** & Pirimiphos-methyl & 305 & 290, 305, 276 & 17.769 \\
**4** & Aldrin & 362 & 263, 265, 261 & 17.866 \\
**5** & Malathion & 330 & 125, 173, 127 & 17.996 \\
**6** & Chloropyrifos & 349 & 197, 199, 314 & 18.223 \\
**7** & Profenofos & 372 & 139, 208, 206 & 20.428 \\
**8** & Ethion & 384 & 231, 153, 125 & 21.693 \\
**9** & Tebuconazole & 307 & 125, 250, 252 & 22.731 \\
**10** & Fenropathrin & 349 & 181, 125, 265 & 23.899 \\
**11** & \(\lambda\)-Cylaholtrin & 449 & 181, 197, 208 & 24.774 \\
**12** & \(\lambda\)-Cylaholtrin (Isomer) & 449 & 181, 197, 208 & 25.034 \\
**13** & Delatemethrin & 503 & 181, 253, 251 & 29.380 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Retention times in GC and characteristic monitored ions for SIM detection of the target pesticides.  
Figure 4: Chromatogram of the target pesticides (1 diazinon, 2 chloropyriphos-methyl, 3 pirimiphos-methyl, 4 aldrin, 5 malathion, 6 chloropyrifos, 7 profenofos, 8 ethion, 9 tebuconazole, 10 fenropathrin, 11 \(\lambda\)-cylaholthrin, 12 \(\lambda\)-cylaholthrin (isomer), and 13 delatemethrin).  
and triazines). The sample preparation procedure involved a solvent-less technique, which provided a simple, reliable, and efficient alternative to traditional methods used for the determination of pesticide residues. The results have shown that the optimized analytical method was adequate for the qualitative and quantitative analysis of pesticides in various water samples with low waste generation and reduced risks to the analyst. The results obtained from 10 water samples extracted with the prepared needle indicated that some of the investigated samples contained pesticides at low concentrations.  
Conceptualization, A.A.A., A.Y.B.H.A. and M.M.A.; methodology, A.A.A., A.Y.B.H.A. and B.H.; software, A.A.A., A.Y.B.H.A. and M.M.A.; validation, A.A.A., A.Y.B.H.A. and B.H.; formal analysis, A.A.A.A. and A.Y.B.H.A.; investigation, A.A.A., A.Y.B.H.A. and M.M.A.; resources, A.A.A., R.A.H. and T.A.; data curation, A.A.A., A.Y.B.H.A. and M.M.M.A.; writing--original draft preparation, A.A.A.; writing--review and editing, A.Y.B.H.A. and B.H.; visualization, A.A.A., A.Y.B.H.A., M.M.A. and B.H.; supervision, A.A.A., A.Y.B.H.A. and B.H.; project administration, A.A.A. and A.Y.B.H.A. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in this study are included in the article, further inquiries can be directed to the corresponding author.  
The authors are grateful to the University of Qassim and the Advanced Materials Research Chair of King Saud University for their support of this research project.  
The authors declare no conflicts of interest.