## 7 Applications
### Other Applications of TF-SPME  
In addition to the diverse applications TF-SPME provides in the environmental and flavor/fragrance fields, many other procedures have been validated with a variety of matrices. Of these applications, one of the most striking uses of TF-SPME has been the analysis of sebum, developed by [PERSON] and colleagues for the non-invasive detection of sebum in vivo [61]. This novel TF-SPME device, utilizing an adhesive thin layer of PDMS, demonstrated good performance in the extraction of sebum and other constituents of skin by a simple placement of the device on human skin, later being thermally desorbed in a TDU/cryo-trap system. This rapid and non-invasive sampling of human skin is crucial for the further development of sampling methods for the cosmetic and pharmaceutical industries. In a similar fashion, [PERSON] et al. introduced a novel in vivo sampling method for the analysis of human skin constituents using a thin layer of PDMS [35]. To prevent saturation of the device from sebum and other common skin oils, the PDMS-TF was emplaced between two pieces of stainless steel mesh and then placed on the surface of skin for sampling (Figure 5). As a result, this developed approach was able to demonstrate great promise for applications in clinical settings due to its high reproducibility and non-invasive sampling procedure. In another example of TF-SPME being well suited for both in vivo and ex vivo sampling in clinical settings, [PERSON] et al. prepared HLB/PDMS and (C\({}_{18}\))/PDMS TF-SPME devices for the investigation of prohibited substances in saliva, analyzed with both LC-MS/MS and GC-MS [52]. Furthermore, this study demonstrated increased analytical precision compared to their similarly developed ex vivo method, confirming the need for more rugged in vivo sampling devices for clinical settings. In 2019, [PERSON] and colleagues reported another application of TF-SPME by use of zeolite-based devices for the extraction of volatile organic compounds (VOCs) in saliva, a class of compounds that is used to determine if a patient has oral cancer [67]. This study again demonstrated the robustness of TF-SPME devices as a non-invasive method. In a more recent study, [PERSON] et al. [39] utilized self-supported TF-SPME prepared according to the method proposed by [PERSON] et al. [36] to extract illicit drugs in both beverages and biofluids. In this study, for the first time, it was demonstrated that the DVB/PDMS TF-SPME devices were suitable for ultrasound-assisted extraction, with a consequent drastic reduction of extraction time prior to direct coupling to a DBDI source. Moreover, this approach allowed rapid quantitative desorption, reducing the likelihood of the thermal degradation of sensitive analytes. As a result, this newly developed method demonstrated several advantageous aspects, including rapid analytical throughput and enhanced sensitivity. With the simplicity for TF-SPME devices to be used as onsite samplers, along with their incredible sensitivity, they have been proven to be suitable tools for environmental analysis, while their fast and non-invasive sampling affords them great potential for both the pharmaceutical and clinical industries (Table 3). Figure 5: The development of polydimethylsiloxane (PDMS) TF-SPME devices for the analysis of skin volatiles. Reproduced from [35], with permission from Elsevier, 2013. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**[PERSON] et al. [19]**} & \multicolumn{3}{c}{**[PERSON] et al. [68]**} & \multicolumn{3}{c}{**[PERSON] et al. [53]**} & \multicolumn{3}{c}{**[PERSON] et al.