## 2 Synthesis and Characterization of MIP
### Polymerization Technique
#### 2.2.4 Suspension Polymerization
Compared to conventional bulk methods whereby the MIPs must be ground and sieved before use, resulting in irregular particles and destruction, MIPs developed using this green solvent are typically obtained as dry free-flowing powder which are pure, sterile, high in yield, and possess a narrow particle size distribution. These advantageous features the need for any further drying or purification steps, making the process ready to be used, and easy to handle [65]. According to [PERSON] et al. [66] to ensure higher greenness for the analytical methods there are several principles, such as: use multi-analyte methodologies over methods using one analyte at a time; and use reagents obtained from renewable sources. In fact, the majority of the current green analytical chemistry principles focus on sample preparation where direct analysis avoiding sampling; use of minimal sample size; perform in-situ measurements; and selection of automated and miniaturized methods. Moreover, solid-phase extraction (SPE) face criticism from a green chemistry perspective due to excessive use of hazardous organic solvents in multistep and laborious procedures. This is the reason why sample preparation is considered as the least green step of an analytical method. MIPs have not been unaware of the green materials synthesis trend. The introduction of several modifications on their synthesis have permitted a decrease in the consumption of organic solvents or their substitution by greener alternatives such as Ionic Liquids (ILs) and deep eutectic solvents (DESs), which can act as porogens, monomers, or even as crosslinkers. Besides, both solvents (Ionic Liquids and deep eutectic solvents) have been also used to improve the green features in other synthesis approaches for other material. The reusability and stability of the imprinted material play a significant role in producing an economic, dependable, sustainable, and ecologically friendly strategy, according to [PERSON] et al. [67]. Polymer degradation compounds are well-known for contaminating samples during their application. The crosslinker, crosslinking degree, condition template extraction, and functional monomer are the four primary parameters that influence MIP reusability and stability. DVB-based polymers exhibited an excellent outcome in terms of crosslinking degree, with DVB-based polymers being able to be reused at least 100 times without losing their template affinity under acidic and basic environments and at elevated temperatures. In contrast to DVB-based polymers, acrylamide and methacrylate-based polymers' crosslinking degree reduced in both acidic and basic conditions due to irreversible breakdown. In molecularly imprinted microspheres (MIMs) preparation, both acrylamide and methacrylate crosslinkers are routinely utilized. Future research on establishing a long-term stable and reusable MIM formulation could face this difficulty. Alternative approaches that can be considered, according to these studies, include the use of green templates, green monomers, green solvents such as porogens and template removal solvents, green crosslinkers and initiators, energy efficiency, the use of ultrasound and microwaves to promote reaction rates, miniaturized techniques, and the use of computational tools for optimizing both the polymer and synthesis process. Higher energy demands have substantial environmental consequences, such as global warming. When compared to conventional heating methods, [PERSON] et al. [68] stated that using comparatively greener energy sources such as microwave and ultrasound for extraction can reduce the impact on the environment and the analyst. [PERSON] et al. [69] proposed a solution based on the green analytical chemistry principle: large volumes of analytical waste should be avoided, and proper management of analytical waste should be pro vided, which includes optimising extraction and clean-up stages using mathematical and statistical modelling. Because of the great selectivity, sufficient clean-up, and enrichment abilities of the imprinted layer, [PERSON] et al.