Solid-phase extraction polymer based

Prepai ative isolation of nonvolatile and semivolatile organic compounds fractions (hydrophobic weak acids, hydrophobic weak bases, hydrophobic neutrals, humic and fulvic acids) from natural and drinking waters in optimal conditions was systematically investigated by solid-phase extraction method with porous polymer sorbents followed by isolation from general concentrate of antropogenic and/or toxic semivolatile compounds produced in chlorination and ozonation processes. 

Currently, perhaps the most promising approach based on the use of molecularly imprinted polymers is solid phase extraction (SPE). Traditionally, when complex samples require a clean-up/enrichment step prior to high-resolution analysis,... 

A fourth conclusion, based on the advantages of the use of solid adsorbents, is the gradual replacement of solvent extractions with solid phase extractions. The movement toward this replacement is already evidenced by the commercial availability of several different cartridges of bonded phases and high-surface-area synthetic polymers. 

Abstract Most analytical applications of molecularly imprinted polymers are based on their selective adsorption properties towards the template or its analogs. In chromatography, solid phase extraction and electrochromatography this adsorption is a dynamic process. The dynamic process combined with the nonlinear adsorption isotherm of the polymers and other factors results in complications which have limited the success of imprinted polymers. This chapter explains these problems and shows many examples of successful applications overcoming or avoiding the problems. 

Zhu, Q. Z., P. Degelmann, R. Niessner, and D. Knopp. 2002. Selective trace analysis of sulfonylurea herbicides in water and soil samples based on solid-phase extraction using a molecularly imprinted polymer. Environ. Sci. Technol. 36 5411-5420. 

Moon J, Jung H, Moon M, Chung B, Choi M (2008) Inclusion complex-based solid-phase extraction of steroidal compounds with entrapped b-cycodextrin polymer. Steroids 73 1090-1097... 

The choice of the sorbent is dictated by the characteristics of both the analytes and their potential interferences. The sorbents most frequently employed here are silica, alkylsilane-modified silica (bonded phases), alumina, porous polymers (with and without ion-exchange groups) and carbon-based materials. One typical application is a method for the determination of hexavalent chromium in soils [10] using the on-line system depicted in Fig. 4.9. After USAL, the analytes in the leachate were directly determined or preconcentrated depending on their concentration. Concentration was performed by on-line solid-phase extraction using a laboratory-made minicolumn packed with a strong anion-exchange resin. The absolute limits of detection were 4.52 and 1.23 ng without and with preconcentration, respectively. 

Huck, C.W. Bonn, G.K. Recent Developments in Polymer-Based Sorbents for Solid-Phase Extraction," J. Chromatogr. A 885, 51-72 (2000). 

G. Theodoridis, C.K. Zacharis, RD. Tzanavaras, D.G. Themelis, A. Economou, Automated sample preparation based on the sequential injection principle. Solid-phase extraction on a molecularly imprinted polymer coupled on-line to high-performance liquid chromatography, J. Chromatogr. A 1030 (2004) 69. 

Many compounds have now been used as template molecules in molecular imprinting. Basically, imprinted polymers can be used directly as separation media. Since all separation applications cannot be described here, some studies recently reported are bsted in Table 7.1. In this chapter, only selected topics, including sensor applications, signaling polymers, molecularly imprinted sorbent assays, molecularly imprinted membranes, affinity-based solid phase extraction, in situ preparation of imprinted polymers, and molecularly imprinted catalysts are discussed. For the reader requiring information on other applications, there are many review articles dealing with these, Recent review articles and books are summarized in Table 7.1. For further development of molecular imprinting techniques, newly designed functional monomers would be desirable. Various functional monomers have been reported and many applications have been conducted. These are summarized in Table 7.2. 

Table 7.3 Imprinted Polymer-Based Solid-Phase Extraction Abbreviations AA acrylamide MAA methacrylic acid VPy vinyl pyridine ...

Ensing, K., Beggren, C., and Majors, R. E., Selective sorbents for solid-phase extraction based on molecularly imprited polymers, LC-GC, 2002, January 2-8, 2002. 

Jonsson, S. and Boren, H., Analysis of mono- and diesters of 0-phthalic acid by solid-phase extractions with polystyrene-divinylbenzene-based polymers, J. Chromatogr. A., 963, 393-400,... 

Major applications of SFE-SFC are somewhat limited at the moment to the analysis of lipids and pesticides from foods and similar matrices and different types of additives used in the production of polymers [79,146,188-194]. The approaches used cover a wide range of sophistication and automation from comprehensive commercial systems to simple laboratory constructed devices based on the solventless injector [172,174,175,188]. Samples usually consist of solid matrices or liquids supported on an inert carrier matrix. Aqueous solutions are often analyzed after solid-phase extraction (SPE-SFE-SFC) to minimize problems with frozen water in the interface [178,190]. The small number of contemporary applications of SFE-SFC reflects a lack of confidence in supercritical fluid chromatography as a separation technique and competition for... 

Kagaya, S., Cattrall, R. W., and Kolev, S. D. 2011. Solid-phase extraction of cobalt(II) from lithium chloride solutions using a Polyvinylchloride-based polymer inclusion membrane with Aliquat 336 as the carrier. Analytical Sciences 27 653-657. 

In addition to studies where the nature of the recognition events per se has been the major issue, a number of application areas have been explored for imprinted matrices viz. (A) Chromatography, where the imprinted polymer is used as the stationary phase for separation and isolation (Chapter 20). This application is based on the fact that the imprinted polymer has a better retention for the template molecules than others. A related area of application is solid-phase extraction, where the imprinted polymer is used as a sponge to concentrate the molecule of interest (Chapter 23). (B) Immunoassay-type analyses in which molecularly imprinted polymers are used as antibody and receptor mimics (Chapter 25). (C) Catalysis where the molecularly imprinted polymers are used as enzyme mimics (Chapter 24). (D) Sensors and biosensor-like devices where the molecularly imprinted polymer is the recognition element (Chapters 26 and 27). 

Recently, Wang et al. [9] developed a microfluidic device that could perform electroki-netic sample fractionation and solid-phase extraction simultaneously. Effluents from a fractionation were subsequently delivered into an array of 36 collection channels containing butyl methacrylate-based monolithic polymer for sohd-phase extraction. Tightly focused sample zones of protein sample could be obtained after electroki-netic fractionation in each of the 36-channel polymer beds without observed cross contamination, indicating great promise for automated operation of these devices in proteomics research. 

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