# Returning to Nature for the Design of Sportive Phases in Solid-Phase Microextraction
## 2 Cork
According to the chemical analysis, at 200 \({}^{\circ}\)C the partial decomposition of suberin, waxes and other extractives occurred. Over 90% of the polysaccharides were degraded at 250 \({}^{\circ}\)C, and lignin started to decompose between 250 and 300 \({}^{\circ}\)C. Nevertheless, the cork coatings showed similar or better extraction efficiencies than polydimethylsiloxane/divinylbenzene (PDMS/DVB) and divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) commercial fibers. Regarding the recent publications, raw cork-based approaches have been highlighted in microextraction methodologies whereas they exhibit some unique analytical features that allow for \"green\", sustainable, and efficient procedures that are relevant to the current environmental concerns [30; 31; 32; 33; 34; 35; 36; 37; 38]. Table 1 points out the analytical features of the recent applications using raw cork-based methodologies for the extraction of different analytes from various matrices. Raw powder cork is produced from cork stoppers after cleaning with ultrapure water and overnight drying at 110 \({}^{\circ}\)C. Further, the powder is prepared using a sandpaper, and the resulting material is sifted to ensure 200 mesh granulometry. Afterward, the resulting powder is conditioned with acetonitrile, and it is ready to be applied as sorbent phase. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Technique** & **Raw Cork Format** & **Analytes** & **Matrix** & **Desorption** & **LOQ (ug/L)** & **Instrumentation** & **Ref.** \\  & & & & & & Volume (μL) & \\ \hline BAuE & Powder & Benzophenone, Trichlocarban and Parabens & Lagoon water & 250 & 1.6–20 & LC-DAD & [30] \\ - BAuE & Powder & Cancer biomarkers & Urine & 100 & 250–300 & LC-DAD & [31] \\ - DFA & Powder & 10 Pharmaceuticals & Urine & 85 & 5–10 & LC-DAD & [32] \\ - TSFME & Powder & Endocrine Disruptics Compounds & River water & 300 & 0.3–15 & LC-DAD & [33] \\ - TSFME & Powder & Endocrine Disruptics Compounds & River water & 300 & 0.8–15 & LC-DAD & [33] \\ - RDSC & Powder & Pathogens & River water & 300 & 0.8–15 & LC-MSMS & [34] \\ - DDK & Powder & 7 Panda and GC & Water & 300 & 0.3–41 & HR-SG-KMS & [35] \\ - DDK & Powder & Parabens and UV filters & Lake water & 100 & 2–43 & LC-DAD & [36] \\ RDSC & Laminar & Hormones & Waskewater & 500 & 0.01–0.062 & GC-MS & [37] \\ RDSC & Laminar & 20 Resticides, PAHs and UV filters & River water & 1000 & 0.3–48 & GC-MS & [38] \\ \hline \hline \end{tabular}
**BAuE**: Bar Adaptive Microextraction; **DFA**: Disposable Peptide Extraction; **TF-SFME**: Thin-Fil Solid Phase Microextraction; **RDSE**: Rotating Disk Sorptive Extraction; **PAHs**, polycyclic aromatic hydrocarbons; LC, liquid chromatography; **DA**: diode array detection; **HR-CS GFAA**: high resolution continuum source graphite furnace atomic absorption spectrometer; GC, gas chromatography; **MS**, mass spectrometry.  
\end{table} 
Table 1: Applications of raw cork-based microextraction techniques for different analytes and matrices. (Reference period: 2015-2019). Raw cork powder has been successfully applied in different microextraction approaches such as bar adsorptive microextraction [30; 31], disposable pipette extraction [32; 35; 36], thin film-solid phase microextraction [33], and rotating disk sorptive extraction [34] as a biosorbent for the reliable determination of organic micropollutants, toxic metals, UV filters, endocrine disruptors, and compounds in aqueous samples as well as pharmaceuticals and lung cancer biomarkers in human urine. Cork exhibits significant hydrophobicity and a number of aromatic rings that can undergo effective \(\pi\)-\(\pi\) interactions with the analytes and substantially enhance the preconcentration ability of the extraction procedures. The last cork-based applications have been focused on improving the mass transfer using laminar cork for rotating disk sorptive extraction (RDSE) methodologies, demonstrating an interesting new configuration for high-throughput procedures [37; 38].