## 3 Sample Preparation Techniques and Development of Extraction Sorbents
### Solid-Based Extraction
#### 3.2.2 Stir-Bar Sportive Extraction (SBSE)  
Stir-bar sorptive extraction (SBSE) is an extraction technique involving partitioning of target analytes between a liquid sample and a stationary section-coated stir bar, by which the SBSE device is directly introduced into an aqueous sample. It was designed to overcome the extraction capacity limitation and fragile coatings in SPME by providing larger, solid-phase volumes [61; 62]. SBSE possesses several advantages over SPME, especially in sensitivity and accuracy for trace level analysis in complex matrices. It is effective for extraction of dilute and low-concentration samples [62; 63]. SBSE has several shortcomings including its incapability to desorb extracted analytes directly into the GC injection port. An additional procedure is required to desorb the analytes into an appropriate solvent, which could affect its sensitivity [63]. Furthermore, commercial, alternative, sorbent materials to polydimethylsiloxane (PDMS) are limited [43]. SBSE presents low recovery for highly polar analytes due to weak hydrophobic interaction owing to the non-polar nature of PDMS [61]. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Year** & **Sorbent** & **Analyte** & **Matrix** & **LOD** & **Recovery (\%)** &
\begin{tabular}{c} **Analytical** \\ **Technique** \\ \end{tabular} & **Ref.** \\ \hline \multirow{3}{*}{2020} & Nitrogen-doped porous carbon & \multirow{3}{*}{14 OPPs} & Fruits and & \multirow{3}{*}{0.23-7.5 ng g\({}^{-1}\)} & \multirow{3}{*}{82.6–118} & GC-MS & [55] \\  & (C-C\({}_{3}\)N\({}_{4}\)@MOF) & & & & & \\ \cline{1-1} \cline{5-7}  & Polydimethylsiloxane (PDMS) & & & & & & \\ \cline{1-1} \cline{5-7}  & Poly(4-nitroaniline)/ & & & & & & \\ \cline{1-1} \cline{5-7}  & poly(vinyl alcohol) & & & & & & \\ \cline{1-1} \cline{5-7}  & electro-monitor & & & & & & \\ \cline{1-1} \cline{5-7}  & Modified hallowise nanotubes & & & & & & \\ \cline{1-1} \cline{5-7}  & diNH/NS & & & & & & \\ \cline{1-1} \cline{5-7}  & Fe\({}_{3}\)O\({}_{7}\)/graphene & & & & & & \\ \cline{1-1} \cline{5-7}  & nanocomposite & & & & & & \\ \cline{1-1} \cline{5-7}  & Polydimethylsiloxane (PDMS) & & & & & & \\ \cline{1-1} \cline{5-7}  & Polydimethylsiloxane/ & & & & & & \\ \cline{1-1} \cline{5-7}  & polyvinylbenzene (PDMS/DVB) & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of past studies on the applications of SPME as a sample preparation technique for OPPs’ determinations. Therefore, there has been a considerable interest among researchers to address the shortcomings of SBSE method. Table 5 shows the summary of past studies on the application of SBSE as a sample preparation technique for OPPs' determinations. The development of SBSE method is primarily focused on the sorbent coating. To date, studies are limited on the application of SBSE, due to limited variety of stir-bar coatings since only PDMS is commercially available. Hence, a new sorbent coating has been prepared by using PDMS in combination with other materials that are commercially available such as polyvinyl alcohol, graphene, and multiwalled carbon nanotubes (MWCNTs) to enhance the extraction performance of SBSE [64; 65; 66]. A new coating for SBSE is necessary to increase the extraction efficiency of OPPs since OPPs consists of a wide range of polarity. Therefore, [PERSON] and [PERSON] [66] prepared a new sol-gel PDMS/PVA-coated stir bar for the preconcentration of five selected OPPs from honey samples prior to GC-FPD analysis. The new PDMS/PVA-coated stir bar exhibited a large surface area (21.248 m\({}^{2}\) g\({}^{-1}\)), which was 500\(\times\) higher than the commercial PDMS coating. It also showed good regeneration and stability, by which it can be used 50\(\times\) without substantial decrease in the extraction efficiency of OPPs. Besides that, the method obtained good LOD (0.013-0.081 ng mL\({}^{-1}\)) and good recovery (81-124%), which indicate its sensitivity and accuracy.