# Green Analytical Chemistry--Recent Innovations
## 3 Innovations in Green Analytical Techniques
### Sustainable Sample Preparation  
Solid-phase microextraction (SPME) and liquid-phase microextraction (LPME) have revolutionized sample preparation techniques by aligning with the principles of green chemistry, offering eco-friendly alternatives to traditional extraction methods. These techniques significantly reduce the use of organic solvents, waste generation, and processing times, making them sustainable and efficient for modern analytical applications. SPME, in particular, employs a coated fiber to adsorb analytes directly from a sample matrix, eliminating the need for large volumes of solvent [48]. This solvent-free approach not only minimizes environmental impact but also enhances method sensitivity and reproducibility. Recent advancements in SPME include the development of novel fiber coatings, such as polymeric and carbon-based materials, which improve selectivity and expand its applicability to a wide range of analytes in fields like environmental monitoring, food safety, and pharmaceuticals [49]. [PERSON] et al. [50] highlighted the revolutionary integration of nanostructured materials, such as metal-organic frameworks (MOFs), into the design of SPME fibers. Their work on polyacrylamide/nickel-based MOF (PAN/Ni-MOF) composites demonstrated significant improvements in extraction efficiency due to the material's high porosity, enhanced surface area, and strong interactions with analytes through mechanisms like hydrogen bonding, hydrophobic contacts, and \(\pi\)-\(\pi\) stacking. These innovations not only allow for the efficient detection of trace-level compounds in complex matrices, such as environmental water and food samples, but also improve the thermal and mechanical stability of the fibers, enabling repeated use without performance loss. LPME, on the other hand, utilizes small volumes of extraction solvents, often in microliter quantities, to isolate analytes [51]. Variants like dispersive liquid-liquid microextraction (DLLME) [52; 53] and hollow-fiber liquid-phase microextraction (HF-LPME) [54] have further refined the technique by enhancing efficiency and reducing solvent usage. DLLME, for example, disperses a minimal amount of extraction solvent throughout the sample matrix, achieving rapid equilibration and high enrichment factors. [PERSON] et al. [55] developed an acid-induced dispersive liquid-liquid microextraction (DLLME) method using in situ hydrophobic deep eutectic solvents (DESs), eliminating the need for toxic dispersive solvents. This green approach, applied to bisphenol A (BPA) and alkylphenols (APs) in environmental and beverage samples, achieved detection limits as low as 0.03 \(\mu\)g L\({}^{-1}\) with high recoveries (86.9-105.0%) and enrichment factors (29-32). The method is rapid (<1 min), solvent-free, and highly efficient, demonstrating the potential of switchable solvent systems in sustainable analytical chemistry. In another recent study, [PERSON] et al. [56] developed a quasi-hydrophobic deep eutectic solvent (DES)-based DLLME for extracting gliflozins from water samples, enhancing green analytical chemistry. The method, using benzalkonium chloride (BZKCl)-based DES, eliminated toxic solvents and improved extraction efficiency. Coupled with UHF-PLC/fluorescence detection, it demonstrated high sensitivity, recovery, and sustainability, as confirmed by green assessment metrics. In a recent review by [PERSON] [52], advancements in dispersive liquid-liquid microextraction (DLLME) were explored to enhance its compliance with green analytical chemistry principles. The review discusses the shift from conventional toxic solvents to greener alternatives, such as deep eutectic solvents (DESs), ionic liquids (ILs), and supramolecular solvents (SUPRASs). Additionally, innovative dispersion strategies, including magnetic nanoparticles, ultrasound, vortexing, and gas stream flotation, have minimized the need for dispersive solvents, improving efficiency and sustainability.