# Applications of Nanomaterial Coatings in Solid-Phase Microextraction (SPME)
## 5 SPME Based on Nanocomposite Materials  
Nanocomposites (NCs) are nanoscale materials made by combining organic and inorganic components, allowing them to incorporate each constituent's distinct features while also generating new functions to fulfill modern material demands. NCs, defined as having at least one component smaller than 100 nm, are solid structures with nanometer-scale spacing between phases. These materials can be made up of an organic matrix and an inorganic nanofiller, or vice versa, or from the hybridization of various organic and inorganic phases at different doping levels. NCs can contain nanoparticles (such as metal or silica), fibrous nanomaterials (such as nanofibers and nanotubes), and layered substances (such as graphite or layered silicates). NCs frequently outperform their individual components in terms of mechanical, electrical, optical, and catalytic qualities. NCs' multifunctional capabilities stem from more than just the sum of their components, with the high surface area-to-volume ratio playing an important role in their distinct structure-property relationships [118; 119; 120; 121]. According to [PERSON] et al., a nanocomposite composed of graphene oxide (GO), poly(methyl methacrylate) (PMMA), and FeO\({}_{4}\) nanoparticles was created specifically for the magnetic solid-phase extraction (MSPE) of aromatic amines. After coating magnetite nanoparticles with GO and PMMA, they created the composite (PMMA@GO-Fe\({}_{3}\)O\({}_{4}\)) and used SEM, TEM, XRD, VSM, and FTIR techniques to characterize it. Their results showed that the composite had preconcentration factors ranging from 139 to 173, successfully extracting amines including aniline and N,N-dimethylaniline. Along with precision with relative standard deviations ranging from 5.9% to 8.6%, they reported detection limits of 2-6 pg/mL. With recoveries of 90.3% to 99.0% when the technique was successfully applied to spiked water samples, its potential for environmental applications was demonstrated [122]. [PERSON] et al. used the sol-gel technique to create a superparamagnetic magnetite nanoparticle (SMNP) and polyethylene glycol (PEG) nanocomposite fiber, which chemically bonded the fiber to a silica surface that had been treated. According to their findings, 13 volatile organic compounds (VOCs) were successfully extracted from water samples using this new fiber. The fiber showed good thermal stability and a long lifespan by adjusting the mass ratio of SMNPs to PEG. According to [PERSON] et al.,the SMNP/PEG fiber demonstrated a broad linear range (0.001-450,000 ng/L), lower detection limits (0.008-0.063 ng/L), and higher extraction efficiency when compared to commercial fibers made of polyacrylate (PA) and polydimethylsiloxane (PDMS). With intraday and interday accuracy ranging from 4.13 to 10.08% and reproducibility ranging from 7.35 to 14.79%, they found that this fiber had good repeatability and reproducibility. According to the authors, the fiber's longevity and chemical stability rendered it appropriate for use in gas chromatography-mass spectrometry (GC-MS) in conjunction with headspace solid-phase microextraction (HS-SPME) in VOC measurement. Its dependability in environmental applications was further proven by tests conducted on tap water, surface water, and groundwater [123]. [PERSON] et al. reported the development of a zinc-based metal-organic framework/polyethersulfone (TMU-4/PES) nanocomposite coating on stainless steel wire for the headspace solid-phase microextraction (HS-SPME) of organophosphorous pesticides (OPPs) from environmental water and soil samples. They stated that the unique characteristics of the TMU-4/PES composite, including its high surface area, porous structure, and \(\pi\)-electron interactions from the PES polymer, contribute to a strong affinity for OPPs. After thermal desorption, OPPs were detected using gas chromatography with a nitrogen-phosphorus detector (GC-NPD). The authors noted the coating's simplicity, stability, and reusability, with up to 100 extraction cycles possible.