Porous polymer sorbents for solid-phase extraction emerged in the 1980s to overcome the limitations of silica and carbon-based sorbents. They have continued to be one of the materials most used for SPE because they have high retention features and a broad availability of interactions. These characteristics are related to their morphological properties and the introduction of different moieties through various synthetic routes. This chapter presents the developments in commercial and in-house prepared macroporous and hypercrosslinked polymer sorbents as well as sorbents with polar and ion-exchange moieties. Their chemical and morphological features are broadly related to the synthetic approach used. Moreover, their evaluation and SPE performance are discussed and illustrated with some examples of their analytical application.

Molecularly imprinted polymers (MIPs) are synthetic polymers with a predetermined selectivity for a given analyte, or group of structurally related compounds, making them ideal materials to be used in separation processes. In this sense, during the past years, a large number of papers have been published dealing with the use of MIPs as sorbents in solid-phase extraction (SPE), namely, molecularly imprinted solid-phase extraction (MISPE). Although the majority of these papers were restricted to describing the use of different templates for different applications, several attempts proposing new alternatives to minimize the inherent drawbacks of the preparation and use of MIPs (i.e., template bleeding, tedious synthesis procedure, etc.) have been reported. Thus, this paper not only intends to provide the basic concepts on the synthesis and use of MIPs in solid-phase extraction (SPE) but also give an overview on the significant attempts carried out during recent years to improve the performance of MIPs in SPE.

Microscale sorbent–based sample preparation techniques comprise of nonmembrane and membrane-protected microextraction, both of which are miniaturized alternatives to solid-phase extraction (SPE). Pipette-tip SPE, microextraction in a packed sorbent, and disposable pipette extraction are categorized as nonmembrane-protected microextraction. When small amounts (milligram to microgram quantities) of micro- or nanosized sorbent materials are used in dispersive SPE, the term micro-SPE (μ-SPE) has been used to describe the procedure. μ-SPE has also been coined to refer to porous membrane-protected sorption-based microextraction. In this μ-SPE approach, the primary feature is a heat-sealed polypropylene membrane envelope within which the sorbent material is enclosed securely. Since the membrane protects the sorbent from possible interfering substances in complex matrices, no further cleanup of the extract is required. This means that sample cleanup, and analyte extraction and preconcentration can be carried out in a single step. Although the other μ-SPE procedures mentioned are briefly introduced and discussed, this chapter is focused on the membrane-protected format of μ-SPE. Representative applications of membrane-based μ-SPE in various fields such as environmental, food, and biological analyses are described, along with an evaluation of the merits and limitations of the procedure.

It is a demand to decrease the time required for sample pretreatment step of the analysis and also to do this step sustainable. This chapter shows that in-tube solid-phase microextraction (IT-SPME) is an attractive technique to achieve these goals. The key factors and state of the art of this technique structured in theoretical considerations, synthesis of designed capillary columns and type of coatings, the different online couplings with liquid chromatography, off-line development and applications during the two last years are discussed. The preparation of new extractive phases including the possibility of applying several external forces (magnetic, electric, thermic), the coupling of IT-SPME with new chromatographic modalities such as miniaturized liquid chromatography, and new uses and utilities are the present of the IT-SPME.

Electrostatic fiber fabrication technique has evinced more interest and attention in recent years, owing to its versatility, reliability, and potential for applications in diverse fields, particularly separation, extraction, and filtration. The sub-micro fibers are generated by employing strong electric field on polymeric solutions or melt is led to the soft nanometric mats. So far, more than 100 polymers have been Electrospun and this number is gradually increasing. Over recent decades, a remarkable variety of electrospun nanofibers as promising and authentic extracting platforms have been synthesized. They offer various advantages including high surface area-to-volume ratio and tunable porosity. Moreover, manipulation of their compositions by means of blending different polymers or hybrid materials on the one hand and alteration of electrospinning instrumentation (e.g., nozzle or collector format) on the other hand have been contributed to various shapes, chemical structures, and morphologies. With these in perspective, we aim to present in this chapter, a comprehensive survey on the electrospinning techniques, different strategies and materials, along with their characterization methods for solid phase extraction purposes.

The evolution of materials, apparatus, and techniques for the solid-phase extraction of gas and liquid samples is described and their virtues placed in a modern context of the requirement for streamlined, efficient, low-cost, and automated sample preparation methods. For gas-solid extraction methods include cartridge- and needle-based packed beds with thermal desorption to recover target compounds and typically gas chromatography for analysis. For liquid-solid extraction cartridge-based, membrane-based (disk), and thin-film based sorbents are used with a wide range of inorganic oxide, low-specificity, and high-specificity sorbents. Second generation formats include microextraction by packed sorbent, solid-phase microextraction, in-tube solid-phase extraction, stir bar sorptive extraction, coated magnetic nanoparticles, nanofibers, and monoliths. Low-specificity sorbent chemistries include silica-based chemically bonded sorbents, macroreticular porous polymers, carbon (activated, graphitized, and carbon nanotubes). High-specificity sorbents include mixed-mode, immunosorbents, aptamers, molecularly printed polymers, metal-organic frameworks, and restricted access media. A general theory of sample processing for cartridge and disk devices is presented for the estimation of breakthrough volumes, rinse solvent conditions, and recovery of target compounds by solvent or thermal desorption.

Polymeric membranes are extensively used in analytical chemistry due to their high surface-to-volume ratio which boosts the mass transference and enhances the kinetics of the extraction. There is a wide variety of commercial membranes that can be adapted (selecting their chemistry, shape, pore size, and thickness) to a given analytical problem. The versatility of these materials can be even broadening if particles (of micro or nanometric size) are loaded on them. These particles can provide the membrane with alternative interaction chemistry than that exhibited by the polymer itself and they can, especially when nanoparticles are used, introduce new properties.

Sorption of metals has appeared an alternative to liquid-liquid extraction owing to its simplicity, low cost, and easy automation. It is a widely used technique for metal isolation and concentration, purification of aqueous streams, and protection against releasing poison metals in the environment. Implementation of more selective and more easy-to-use sorbents may result in simplification the activities mentioned above and a diminution of the risk of accidents.

Carbon-based adsorbents have become since decades an important group of solid phases in the field of Analytical Chemistry. This family of sorbents includes fullerenes, graphene, carbon nanotubes, nanohorns, nanodiamonds, nanofibers, quantum dots, etc., as well as their functionalized forms, so their potential is really huge. When they are selected correctly for the required application, they can show a powerful extraction behavior and lots of advantages, such as selectivity, excellent adsorption capacity, thermal and chemical stability, etc. However, it is worth mentioning that these materials may also demonstrate some drawbacks, such as their relatively high cost, their poor batch-to-batch reproducibility, and the limited number of commercial traders available. Nevertheless, it is obvious that their interest is still very high and, on the rise, today. In this chapter, we will describe the use of carbon-based sorbents in the field of solid phase extraction, including all the different modalities.

Matrix solid phase dispersion (MSPD) is a technique widely used in sample preparation for the extraction of chemical constituents from fruits and plants, as well as for the extraction of organic contaminants from food and environmental samples. The latest trends in sample preparation using MSPD are discussed, providing an overview of the analytical methods published in the last 5years, such as the use of several sorbents during the extraction process for the simultaneous cleanup of the extract, the combination of this technique with other extraction procedures, and the development of new sorbents to provide a more selective and efficient extraction.