Solid-phase extraction sorbent selection

Magiera, S., Hejniak, J., Baranowski, J. Comparison of different sorbent materials for solid-phase extraction of selected drugs in human urine analyzed by UHPLC-UV. J. Chromatogr. B 958, 22-28 (2014)... 

Andersson, L. I. Paprica, A. Arvidsson, T., A highly selective solid-phase extraction sorbent for preconcentration of sameridine made by molecular imprinting, Chromatographia 1997, 46, 57-62... 

Dzygiel, P. O Donnell, E. Fraier, D. Chassaing, C. Cormack, P. A. G., Evaluation of water-compatible molecularly imprinted polymers as solid-phase extraction sorbents for the selective extraction of sildenafil and its desmethyl metabolite from biological samples, J. Chromatogr. B 2007, 853(1-2), 346-353... 

Theodoridis, G. Manesiotis, P. Selective solid-phase extraction sorbent for caffeine made by molecular imprinting. J. Chromatogr. A. 2002, 948 (1-2), 163-169. 

Zhang, Z. Zhang, H. Hu, Y. Yang X Yao, S. (2010d). Novel surface molecularly imprinted material modified multi walled carbon nanotubes as solid phase extraction sorbent for selective extraction gallium ion from fly ash. Talanta, 82, 304-311. 

The low selectivity of the SPE columns currently in use can be increased with more selective sorbents such as the immunosorbents, which have been quite extensively used in SPE-LC (72). Immunoaffinity-based solid-phase extraction (lASPE) sorbents have also been used in coupled gas chromatography for determining... 

Solid phase extraction (SPE) involves the separation of components of samples in solution through their selective interaction with and retention by a solid, particulate sorbent. SPE depends on differences in the affinities of the various components of the sample for the sorbent. The mechanisms of the interactions are virtually identical to the sorption processes that form the basis of liquid chromatographic separations (p. 80). The choice of solvent, the pH and ionic strength of aqueous solutions, and the chemical nature of the sorbent surface, especially its polarity, are all of importance in controlling the selectivity and efficiency of an extraction. 

Application of SPE to sample clean-up started in 1977 with the introduction of disposable cartridges packed with silica-based bonded phase sorbents. The solid phase extraction term was devised in 1982. The most commonly cited advantages of SPE over liquid-liquid extraction (LLE) as practiced on a macroscale include the reduced time and labor requirements, use of much lower volumes of solvents, minimal risk of emulsion formation, selectivity achievable when desired, wide choices of sorbents, and amenability to automation. The principle of operation consists of four steps (1) conditioning of the sorbent with a solvent and water or buffer, (2) loading of the sample in an aqueous or aqueous low organic medium, (3) washing away unwanted components with a suitable combination of solvents, and (4) elution of the desired compound with an appropriate organic solvent. 

Pap T et al (2002) Effect of solvents on the selectivity of terbutylazine imprinted polymer sorbents used in solid-phase extraction. J Chromatogr A 973(1-2) 1-12... 

Analytes may accumulate in the sorption phase either by adsorption onto the surface of solid sorbent materials or by absorption in absorbent liquids or polymers that behave like subcooled liquids.The advantage of solid adsorbents is the potential to select materials with a high affinity and selectivity for target analytes. However, the sorption capacity of adsorbents is usually limited, and the description of adsorption/desorption kinetics of analytes to adsorbents is complex. Typically, the adsorbent materials used in passive samplers are similar to those used in solid-phase extraction techniques. 

Solid-phase extraction (SPE) has evolved to be an important sample preparation technique, due to its ease of automation, high analyte recovery, and excellent selectivity. The commercial availability of compact SPE devices with a wide selection of sorbent materials adds to their attraction. A major advantage of SPE is that multiple samples can be prepared in parallel using low volumes of solvents. 

Solid-phase extraction (SPE) is one of the most commonly used sorbent extraction techniques. The analytes are extracted together with interfering compounds with some similar characteristics by passing a usually aqueous sample through a plastic cartridge containing dispersed sorbent on a particulate support. A selective organic solvent is normally used to remove interferences and a different solvent is then employed to elute the retained analytes. This technique has a number of attractive features as compared with traditional solvent extraction. Thus, it is quite simple and inexpensive, can be automated and used in the field, and uses relatively small amounts of solvents. Particle-load... 

Solid-phase extraction (SPE) is based on low-pressure liquid chromatography, where a short column is filled with an adsorbent. The separation mechanisms are based on the intermolecular interactions among analyte molecules and functional groups of sorbent. The choice of eluent is made by the relationship between the eleutropic value (2°) and the analyte polarity. SPE is fast, selective, and economical if compared with the extraction methods described previously. It can be applicable to both nonpolar and polar analytes, but both matrix and analyte must be in the liquid state. 

The purification procedure should remove potentially interfering compounds and, moreover, fractionate the entire spectrum of cytokinins into groups. It is usually not possible to analyze nucleotides and O-glucosides together with free bases, ribosides and iV-glucosides. Classical liquid-liquid partition steps [274] have been recently replaced by less labor-intensive, rapid and selective solid-liquid extraction. When applied in neutral aqueous solutions, cytokinin nucleotides are retained on weak anion-exchangers (DEA -Sephadex, DEAE-cellulose), while the other cytokinin forms are retained on reversed phase sorbents. Dobrev and Kaminek [275] used mixed-mode solid-phase extraction for step-wise... 

Numerous articles can be found on the use of sorbent materials such as silica, stainless steel beads, and common solid-phase extraction materials for collection of supercritical fluid-extracted analytes.38 2 In this scenario the fluid is usually allowed to expand into a gas, which is forced through a packed bed of solid sorbent material. The analytes are bound or simply deposited and cryogenically trapped onto the sorbent and are later eluted with appropriate solvents. The advantage of this technique is that further cleanup can be performed by carefully selecting the eluting solvent. 

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