## 1 Introduction
Another research group has prepared a fiber consisting of a stainless-steel wire coated with a mixture of PDMS and C\({}_{18}\) particles. This coated wire was used for the extraction of six organo-chlorine pesticides by DI-SPME in water samples, followed by GC-MS measurements [33]. [PERSON] and his research group have evaluated the occurrence of insecticides in surface waters using microextraction with commercial fibers coated with PDMS (7 \(\upmu\)m and 100 \(\upmu\)m) and PA (85 \(\upmu\)m), the latter being more efficient for extraction of most pesticides. Additionally, a comparison of the two SPME modes revealed that the direct immersion mode (DI-SPME) allowed for the extraction of more target analytes with higher efficiency than the headspace mode (HS-SPME) [34]. The occurrence of 23 pesticides in water sampled from Brazilian cities was studied by [PERSON] et al., who developed and optimized a procedure based on DI-SPME using a fiber with a bipolar porous coating [35]. A novel SPME fiber coated with a layer of a highly porous zirconium-based metal-organic framework was developed by [PERSON] et al. for direct immersion extraction of organochlorine pesticides in water samples. This fiber showed better extraction efficiencies than commercial fibers, with 2-20 times higher enrichment factors. Moreover, the prepared coated fiber also exhibited higher extraction efficiencies toward polycyclic aromatic hydrocarbons and nitrobenzenes [36]. For extraction of pesticides from aqueous samples by DI-SPME, [PERSON] et al. have prepared a fiber coated with a material consisting of silicone sealant and a hollow zinc oxide-cerium oxide composite. The high hydrophilicity of SPME solvents enhances the detection of pesticides when using chromatographic analysis [28; 37]. A novel stable and crosslinked chitosan/graphene oxide aerogel was prepared and used as a coating for DI-SPME by [PERSON] et al. in 2022. The high porosity and large surface area of this material resulted in high extraction performance towards various hydrophobic pollutants, such as pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyl, in comparison with two commercial fibers [38]. In 2018, [PERSON] et al. developed a new SPME device consisting of a platinum wire covered with polypyrrole-zinc oxide nanorods. They used this organic/inorganic nanocomposite wire for microextraction and quantification of pesticides in agricultural water samples by DI-SPME and GC-MS and reached LOD values of about 0.1 ng mL\({}^{-1}\)[39]. A method for the synthesis of carbon nanomaterials was developed by [PERSON] and co-authors by chemical vapor deposition. The carbon nanoparticles were supported on steel threads applied for pre-concentration and extraction of 24 insecticides from water, using both direct immersion and head-space modes. Their results showed low detection limits, with LOQs from 0.0007 to 3.7320 \(\upmu\)g L\({}^{-1}\)[40]. A method for the fabrication of SPME fiber was described by [PERSON] et al. who prepared a polyoxometalate-based ionic liquid that was immobilized onto a stainless-steel wire. This new coated nanomaterial was assessed for the extraction of six triazole pesticides from head-space and aqueous samples, using GC-MS. Excellent repeatability was obtained for the target analytes, while the detection limits were in the range of 7-40 pg mL\({}^{-1}\)[41]. The concentration of organochlorine pesticides in water was determined by SPME using coatings based on gold nanoparticles developed by [PERSON] et al. in 2017, followed by GC-ECD. Despite the small thickness of the uniform coating, about 3 \(\upmu\)m, this homemade needle allowed them to reach detection limits down to 0.13 ng mL\({}^{-1}\) and extended lifetime. The extraction efficiency of this device was also higher than that of the commercial polyacrylate needle [42]. The interferences caused by the matrix effect on the quantification of pesticides in aquatic matrices by SPME-GC-FID were explored by [PERSON] and his colleagues in 2017.