## 2 Sorbent-Based Sportive Microextraction Techniques  
Sorbent-based sorptive microextraction techniques utilize a solid/semi-solid organic polymer as the sorbent, immobilized on a substrate (such as fused silica fiber, silica particles, glass-coated bar magnet, cellulose/polyester/fiber glass fabric etc. ), and include solid phase microextraction (SPME) and its different modifications and implementations, stir bar sorptive extraction (SBSE), microextraction by packed sorbent (MEPS), thin film microextraction (TFME), and fabric phase sorptive extraction (FPSE). Sampling and sample preparation using these techniques are often carried out either by (1) headspace extraction; or by (2) direct immersion extraction. Due to the glue-like, highly viscous polymeric sorbents are prone to irreversibly adsorb matrix interferents from the sample matrix, direct immersion extraction can only be done when the aqueous sample is free from particulatesor macromolecules. As such, biological, environmental and food samples require rigorous sample pretreatment prior to analyte extraction such as filtration, centrifugation, protein precipitation, etc. Once the analytes are extracted into these devices, desorption can be carried out by applying thermal shock or by exposing to an organic solvent. Due to the special geometrical advantage (fiber retractable inside a syringe needle), SPME fiber can be introduced directly into GC inlet or into the HPLC system via a special interface. For SBSE or FPSE, a thermal desorption unit can be used. Alternatively, solvent mediated desorption can be used followed by injecting an aliquot into GC or HPLC for chromatographic separation and analysis. Fiber-Based Solid-Phase Microextraction, Capillary Solid-Phase Microextraction, and Related Techniques  
Solid-phase microextraction (SPME), invented by [PERSON] in 1987, undoubtedly deserves the credit for beginning a new era in analytical sample preparation characterized by solvent-free extraction, miniaturization and automation. SPME integrates sampling, extraction and analyte preconcentration into a single step. Due to this ease of interfacing with other analytical systems, as well as many other advantages, SPME has been enjoying exponential growth in applications in many different areas since its inception. The miniaturization of sample preparation techniques and the integration, particularly in _on-line_ configuration, of chromatographic instruments that could allow a reduction in labor-intensive manual operation and help to enhance the overall analytical performance [12] still remain the major focus in academic and industrial research. In this scenario, even if MEPS is more easily automated than SPE, and more robust than solid-phase microextraction (SPME) [13], sorbent-based techniques and their different formats certainly represent a valid choice. These techniques provide simplicity in their operation, consume no solvent or minimize solvent usage, allow the separation and pre-concentration of the analytes using different commercial fibers, and the possibility of automating the entire process could be successfully applied in food, environmental, clinical, pharmaceutical and bioanalysis applications [14; 15; 16], as recently reviewed by [PERSON] and co-workers [17]. The fibers, which are commercially available, may be different based on their type:  
* non-bonded phases: stable with some water-miscible organic solvents, although some swelling may occur when used with non-polar solvents,
* bonded phases: stable with all organic solvents, except for some non-polar solvents,
* partially cross-linked phases: stable in most water-miscible organic solvents and some polar solvents,
* highly cross-linked phases: similar to the partially cross-linked phases, except that some bonding to the core may occur.