## 2 Solid-Phase Microextraction
Porogens are sometimes required to attain a porous morphology and thereby enhancing mass transfer [25]. A new polymerisation strategy called molecular imprinting solid-phase microextraction (MISPME) has been developed in different formats, such as MIP-coated fibres (polymeric membranes) and MIP rod-like fibres (polymeric monolithts). MISPME is a successful and novel microextraction technique that enriches the selected analytes from various real samples, including environmental samples [26]. Bisphenol A [27], phthalates [28] and triazines [29] in liquid samples have been detected through this strategy. Ionic liquids/polymeric ionic liquids (ILs/PILs) are promising sorbent-coating materials designed to exhibit high selectivity for targeted analytes. ILs are salts with organic cations and organic/inorganic anions with melting points at or below 100 \({}^{\circ}\)C. These materials possess high thermal stability, tuneable viscosity and solvation capabilities and negligible vapour pressures. The primary advantage of using ILs as SPME sorbent coatings involves the ability to incorporate various substituents into the IL structure [30]. PILs are polymers synthesised from IL monomers that exhibit some advantages over ILs when used as coatings for SPME. PILs often possess higher viscosities and greater mechanical strengths compared to ILs but exhibit similar extraction selectivities [30]. Although studies of IL/PILs-based sorbent coatings in SPME have become extremely popular, the stability must be improved to enhance the robustness of the coating when studying new sorbent-loading methodologies and fibre surface modifications. Both ILs and PILs have been widely used as SPME coatings in numerous applications, especially for the analysis of water samples, through both direct immersion and headspace; all of these methods have been coupled to GC [30]. In-tube SPME, which is the capillary format of SPME, utilises a tubular extraction device that contains an extraction phase as a surface coating or monolithic sorbent bed. In-tube SPME is also known as capillary microextraction (CME) [18]. In this case, the sorbent medium plays the most significant role during sample preparation; it is highly selective for the target analyte and should be thermally and chemically stable, providing highly efficient extraction. Unlike SPME fibres, the coated capillaries are not commercially available. Toward that purpose, a small selection of commercially available GC columns is used [31]. [PERSON] _et al._[32] optimised this microextraction technique to extract oestrogens from environmental liquid samples using Carboxen and Supel-Q capillary columns. However, the low sorbent loading, which resulted from the thin stationary phase coatings in the used GC column segments, results in low sample capacity, impeding the pre-concentration step. In the last decade, sol-gel coatings and monolithic beds have been developed to solve the in-tube SPME problems (e.g., low sorbent loading) in order to overcome this format-related deficiency [18]. Micellar media have been used as alternatives to organic solvent during IT-SPME [33]. Similarly to SPME, stir bar sorptive extraction (SBSE) is also an equilibrium-based non-exhaustive sample-preparation technique. However, the major difference between SPME and SBSE is the high sorbent loading on the stir bars, which imparts increased sample pre-concentration capabilities. During stir bar sorptive extraction (SBSE), a magnetic stir bar coated with polydimethylsiloxane (PDMS), which has a larger surface area than a SPME fibre, is spun into an aqueous sample (or extract) for a selected long extraction time. Once the extraction step is completed, the stir bar is removed, a step that is usually performed manually, and a fraction of the concentrated extract is transferred to a GC system or diluted for LC analysis [34].