## 4 Dispersive Micro Solid-Phase Extraction
Under SIM mode, each drug was monitored using one quantifier and six qualifier ions. High determination coefficients \(r^{2}\) (>0.995) were recorded with LOQs ranges of 0.2-0.4 ng/mL. Acceptable recoveries (92.9-103.2%) with an RSD < 4.7% were noticed. An analogous magnetic d\(\upmu\)SPE protocol coupled with GC-MS was developed for the determination of tramadol and fluoxetine in environmental water and biological samples [74]. Graphene oxide-modified Fe\({}_{3}\)O\({}_{4}\) was prepared and utilized as the sorbent. Figure 6: Analytical steps of the DuSPE-DES-LLME for the determination of tricyclic antidepressant drugs. (Adapted from [71] with permissions). The screening of the most critical parameters was performed using the Plackett-Burnam design in 16 experiments. The desorption time, pH, and desorption solvent volume had a negative effect, and the stirring rate had a positive effect on the response. After optimization, the sample pH, desorption time, stirring rate, and desorption solvent volume were 2.2, 7.8 min, 1600 rpm, and 230 uL, respectively. Compared to other published approaches, the method showed better accuracy, within a range of 96.2-103.9%. The method showed a wide linear range of almost three orders of magnitude, which was superior to the reported approaches. The same analytes were determined in urine samples using a DLLME assisted by magnetic carbon composite Du\(\upmu\)SPE followed by GC-MS analysis [75]. The samples were initially combined with a novel magnetic and porous adsorbent, composed of MOF-derived NH\({}_{2}\)-functionalized Fe\({}_{3}\)O\({}_{4}\) nanoparticles. The eluent was directly utilized as the disperser solvent alongside CH\({}_{2}\)Cl\({}_{2}\) as the extracting solvent for DLLME. The combination of these techniques offered remarkable enrichment factors and extraction recoveries due to the advanced high-surface-area sorbent. Linear ranges of 0.1-30 ng/mL for tramadol and 0.1-35 ng/mL for methadone were achieved, with LODs of 73 and 32 pg/ mL, respectively. The authors compared the results of their method with those obtained from the standard HPLC/MS-MS approach, which were in good agreement. [PERSON] et al. published a polymer-based dispersive solid-phase extraction combined with DES-based DLLME for the determination of four hydroxylated PAHs from urine samples [76]. The authors took advantage of using 175 mg of polystyrene dissolved in 1.5 mL of isopropanol rapidly injected into the sample solution. After centrifugation at 1120\(\times\)\(g\), the adsorbed analytes were eluted using choline chloride/dichloroacetic acid, and the supernatant was further mixed with choline chloride/3,3-dimethyl butyric acid and dispersed in aqueous solution. The final sedimented phase was injected into GC-MS. Increasing the polystyrene amount, the extraction efficiency was also increased up to 175 mg, while no effects were observed by changing the sample pH in the range of 2-10. Analysis of the urine samples collected from tobacco smokers revealed the presence of 1-hydroxynaphthalene and 2-hydroxy-naphthalene, with concentrations ranging from 29 to 53 and 43 to 84 ng/L, respectively.