## 2 Hybrid Graphene-Based Materials (Hybrid GBMs)
### Magnetic Materials  
The continual advancements in sample preparation within the scientific realm have paved the way for the introduction of magnetic nanoparticles (MNPs) or magnetic beads (MBs) as sorbent materials in countless miniaturized extraction strategies [55; 56]. According to [PERSON] [57], the magnetism inherent in these materials primarily stems from spinel ferrites (MFe\({}_{2}\)O\({}_{4}\), where M represents Fe, Co, Mn, Ni, or Cu). Moreover, the authors assert that magnetic materials offer the advantage of being straightforward and cost-effectivelysynthesized, presenting remarkable application versatility. On the other hand, common drawbacks include their tendency to form agglomerates and undergo oxidation [56] quickly. Consequently, conventional strategies use inorganic protection or organic coatings to enhance their chemical stability [21; 57]. Furthermore, given their active sites containing hydroxy, amino, or vinyl groups, the literature has increasingly demonstrated the potential functionalization of magnetic materials, particularly GBMs, for their application as sorbent materials in miniaturized extraction approaches [26; 57]. The utilization of G in the synthesis of MNPs and MBs has showcased a remarkable synergy, leveraging the inherent properties of graphene. This synergy is particularly evident due to graphene's robust \(\pi\)-\(\pi\) stacking interactions, mechanical durability, and thermal resilience [27]. Moreover, graphene-based magnetic materials are mainly fabricated by physical attachment or covalent binding [58]. The first approach is often regarded as the simplest, involving the straightforward mixing of graphene-based materials and MNPs either in solution or through the in-situ growth of MNPs. Conversely, covalent bonding entails an amidation reaction with crosslinking reagents, such as N-hydroxisuccinimide (NHS). Furthermore, the exploration of GO and rGO for their magnetization and application as sorbents in sample preparation techniques shows significant potential for their use as MNPs [57]. Most recently, [PERSON] et al. [59] reported an ex-situ magnetization method for rGO material. The technique mainly involves the mixing and interaction of two previously prepared phases. The authors highlighted that, while the in-situ approach is commonly employed for producing graphene-based magnetic materials due to its one-step execution, it still suffers from limited control over reaction products and by-products. For the experimental part, the start rGO nanoparticles were immersed in a suspension of 1 mg mL\({}^{-1}\) of Fe\({}_{2}\)O\({}_{4}\)-NPs for four days with later filtration and drying (50 \({}^{\circ}\)C). While the study highlights the significant potential for scalability, its drawbacks primarily stem from challenges related to the dispersion of nanostructures within the matrix. Therefore, future studies are needed to address this challenge effectively. Apart from this, an intriguing comparative study was proposed by [PERSON] et al. [60], in which the authors conducted a comparison between iron magnetic nanoparticles-doped graphene oxide (Fe\({}_{3}\)O\({}_{4}\)-GO) synthesized via both in-situ and ex-situ approaches. The results primarily highlighted the larger specific area of Fe\({}_{3}\)O\({}_{4}\)-GO obtained by the in-situ approach compared to those from the ex-situ method. However, each approach's advantages and drawbacks must be thoroughly evaluated before determining the optimal synthesis method for obtaining Fe\({}_{3}\)O\({}_{4}\)-GO sorbent materials. Although in-situ approaches offer simplicity, the physical adsorption between magnetic materials and graphene-based nanoparticles may not ensure sufficient stability for repetitive use. In contrast, covalent bonding offers intriguing versatility in fabricating carbon-based MNPs. [PERSON] et al. [33] reported the development of graphene oxide-based magnetic covalent organic framework composites (GO@MCOFs).