## 7 Applications  
### Environmental Analysis  
The applications of TF-SPME have been traditionally environmental in nature, as much of their development has been expedited by the need for rugged and high capacity samplers, both passive and active. Initial progress toward highly efficient samplers with greater surface-to-volume ratios were developed to meet the need for the trace level extraction of contaminants found in complex environmental matrices, but these matrices proved to be challenging due to a variety of parameters such as large volumes for air analysis or the incredible sensitivity needed for persistent contaminants in aqueous media. Under these circumstances, the enhanced sensitivity of TF-SPME coupled with its convenient geometry for both extraction and introduction to onsite and benchtop instrumentation affords it the opportunity to outperform other SPME technologies in trace level environmental analysis. Initial developments of membrane-based TF-SPME were evaluated by the extraction of polycyclic aromatic hydrocarbons (PAHs) from aqueous samples [12]. PAHs, a class of hydrophobic semivolatiles that are commonly released into the environment through the combustion of hydrocarbons and other organic matter, continue to rise in their environmental significance as they are readily distributed throughout biosystems and are a known cause of cancer among other mutagenic effects [57]. Since then, many studies have analyzed PAHs from aqueous samples using TF-SPME in various different modes, utilizing PDMS film [16; 49; 58; 59], TF-SPME membrane [20] and an alternative thin film-based sampler using polymer-coated aluminum [45]. In addition, glass fiber reinforced TF-SPME has also been used for the analysis of PAHs in aqueous samples, using polyacrylate coatings to extract PAHs along with  
Figure 4: The different coating methods for preparation of TF-SPME devices. organochlorous and organophosphorus pesticides, demonstrating greatly enhanced efficiency with the partition coefficients for the TF-SPME device being up to 15 times higher than the SBSE device [32]. Less conventional extraction phases have also been introduced, as the recent success of carbonaceous nanomaterials being suitable extraction phases for SPME have led the path toward the development of mixed-mode carbonaceous TF-SPME devices. These carbonaceous TF-SPME devices have in turn been proven to be effective in the extraction of different organic compound classes, an example again being the analysis of PAHs in aqueous samples [20]. Furthermore, the analysis of PAHs have also been performed using other \"parallel\" thin film technologies, that is, extraction which utilizes a large surface area but does not exemplify the large phase volume needed for enhanced sensitivity. This is accomplished using PDMS-coated vials for the determination of PAHs in soil [46]. Similar alternative geometries have also been tested for their uses as passive samplers, such as ethylene-vinyl acetate (EVA) coated glass fibers for the aqueous extraction of pesticides [48] and EVA coated glass cylinders for the air sampling of volatile PCBs [44]. TF-SPME devices made of pure monophasic extraction phase, such as the first generation of TF-SPME devices [12], are still used in some studies as passive samplers. In the case of pyrethroids, a class of significantly hydrophobic insecticides that are known to cause damage to beneficial insects and fish, the suitability of TF-SPME has been just recently studied using thin films (25-500 \(\upmu\)m) of different materials (silicon, polyethylene, polymethylmethacrylate, polyoxymethylene and polyurethane) as passive samplers [60]. Another alternative geometry of passive sampling, sorptive tape extraction (STE) [61], has also been effectively used for the direct sampling of plant volatiles [33; 62] by both headspace and direct application to the plant surface.