## 3 Results and Discussion
### Application of MISPE  
To evaluate the optimized MISPE, serum was selected for recovery testing through the standard addition method. The SLX was spiked into the serum at 2 \(\mathrm{\SIUnitSymbolMicro}\)/mL. The recovery data, presented in Figure 8, showed that the optimized MISPE could successfully extract SLX from the spiked serum. It should be noted that these recoveries are indicative of the good performance of the MISPE. MIP3 showed the highest recovery (96.59 \(\pm\) 2.24%) compared to the other MIPs or NIP. This result was better than the previous study with the bulk method (92.17 \(\pm\) 2.66%) [7] and indicates that MIPs obtained with the precipitation method show better recognition than the other method. This result correlates with the adsorption capacity obtained in the previous stage. Table 3 shows a comparison of our method to the other study on SLX analysis in blood plasma. The method is comparable to another study on SLX analysis in blood plasma using a more sensitive technology, such as LC-MS/MS assays, as shown in the table. As a result of these findings, we may conclude that our study's selectivity is comparable to that of the other. To compare the performances of the synthesized MIP with the available sorbent, the analysis of SLX was also performed using C-18 cartridges as a references [64]. As can be seen in Figure 9, MIP3 (96.594 \(\pm\) 2.24%) has higher peaks of SLX (retention time 9.28 min) than C-18 (79.11 \(\pm\) 2.96%), which means that MIP has a better affinity to SLX than C-18 in serum. The recovery of MIP3 from the precipitation method was much higher than that of  
Figure 8: The recoveries of SLX from serum spiked with SLX 2 \(\mathrm{\SIUnitSymbolMicro}\)/mL. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Target** & **Preparation Sample** & **Instrument** & **Repeatability** & **\% Recovery** &
\begin{tabular}{c} **Limit of** \\ **Quantification** \\ \end{tabular} & **Reference** \\ \hline Salmeterol & SPE & HPLC & 3.7–16.3\% & 74–84\% & 2.0 ng/ml & [60] \\ Salmeterol & SPE & LC-MS/MS & 1.86–6.12\% & 98.31–100.00\% & 2.0 pg/mL & [61] \\ Salmeterol & \multirow{2}{*}{LLE} & \multirow{2}{*}{HPLC} & \multirow{2}{*}{\textgreater{}2.2\%} & \multirow{2}{*}{98.2–102.7\%} & \multirow{2}{*}{0.025 \(\mathrm{\SIUnitSymbolMicro}\)/mL\({}^{-1}\)} & \multirow{2}{*}{[62]} \\ xinafoate & & & & & & \\ Salmeterol & \multirow{2}{*}{LIME} & \multirow{2}{*}{HPLC} & \multirow{2}{*}{6.0–8.5\%} & \multirow{2}{*}{\textgreater{}90.0\%} & \multirow{2}{*}{0.30 ng/ mL} & [63] \\ xinafoate & & & & & & \\ Salmeterol & \multirow{2}{*}{LLE} & \multirow{2}{*}{LC-MS} & \multirow{2}{*}{8.8–13.7\%} & \multirow{2}{*}{103.6\%} & \multirow{2}{*}{2.5 pg/mL} & [64] \\ xinafoate & & & & & & \\ Salmeterol & \multirow{2}{*}{MISPE} & \multirow{2}{*}{HPLC} & \multirow{2}{*}{1.7–6.8\%} & \multirow{2}{*}{98.7\%} & \multirow{2}{*}{6.3 ng/ml} & \multirow{2}{*}{Our result} \\ xinafoate & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of repeatability, recovery, and LOQ values with other research studies. the previous bulk method (92.17 \(\pm\) 2.66%) [7], which showed that the present polymers have a better analytical performance than before. Physical Characterization of Sorbent with Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR)  
BET analysis (Table 4) shows that the MIPs from the precipitation method have a larger surface area than those of the previous bulk method, which causes the surface capacity for adsorption to be higher and more of the analyte to be adsorbed. Usually, larger surface area indicates better formed particles [65]. The suitable surface area provides the possibility to ensure the correct permeability conditions (good analyte migration through the polymer structure and increasing the probability of reaching the binding site for a given chemical compound) for the sample and organic solvents during analyte collection, as well as the extraction process [66].