Sorption solid-phase extraction

If the distribution ratio of the analyte is fairly high (D >100), but that of the accompanying ions are low, separation with selective sorption (solid phase extraction) can be achieved. 

Osman, M.M. Kholeif, S.A. Abou Al-Maaty, N.A. Mahmoud, M.E. Metal sorption, solid phase extraction and preconcentration properties of two silica gel phases chemically modified with 2-hydroxy-1-naphthaldehyde. Microchimica Acta 2003, 143 (1), 25. 

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. 

Nakamura, M., Suzuki, T., Amano, K., and Yamada, S. Relation of sorption behavior of agricultural chemicals in solid-phase extraction with their n-octanolAvater partition coefficients evaluated by high-performance liquid chromatography. Anal Chim. Acta, 428(2) 219-226, 2001. 

Solid-phase extraction could be coupled online with HPLC. This is becoming increasingly important, because it makes it possible to handle all the situations in which large series of samples have to be analyzed routinely, and therefore rapid, (semi-) automatic, and unattended analysis is an aspect of major concern. Moreover, sensitive trace level determination requires the analysis of total samples or sample extracts rather than aliquots, under conditions in which analyte losses, due to evaporation or irreversible sorption to the vessels walls, and contamination, caused by the solvent or reagents used, laboratory air, and/or sample manipulation in general, must be rigorously minimized (45,46). 

Ohlenbusch, G., M. Kumke, and F. H. Frimmel. 2000. Sorption of phenols to dissolved organic matter investigated by solid phase extraction. Science of the Total Environment 253 63. 

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. A sample preparation technique using liquid-solid sorption to remove contaminants from the sample or isolate the sought for compounds from the sample. 

Recently, Hawthorne et al. coupled the ASE technique to solid-phase extraction using sorption discs that were placed in the extraction chamber together with the sample in order to simultaneously concentrate and extract polar compounds such as acid herbicides and their esters from soils, using strong anion-exchange (SAX) discs [99]. They also used this combined methodology to develop a convenient method of shipping extracts from field sites to the analytical laboratory [100]. In the former application, the esters of the... 

Solid-phase extraction (SPE) is a method of sample preparation that concen-Irates and purifies analytes from solution by sorption onto a disposable solid-phase cartridge, followed by elution of the analyte with a solvent appropriate for instrumental analysis. The mechanisms of retention include reversed phase, normal phase, and ion exchange. Traditionally, sample preparation consisted of sample dissolution, purification, and extraction that was carried out with liquid-liquid extraction. The disadvantages with liquid-liquid extraction include the use of large volumes of organic solvent, cumbersome glassware, and cost. Furthermore, liquid-liquid extraction often creates emulsions with aqueous samples that are difficult to extract, and liquid-liquid extraction is not easily automated. These difficulties are overcome with solid-phase extraction. Thus, solid-phase extraction was invented in the mid-1970s as an alternative approach to liquid-liquid extraction. 

Separation of elements from interfering ions by solid phase extraction using polyurethane foam provides the examples of enhancement in selectivity of spectrophotometric methods [33-35]. Sorption of thiocyanate complexes of the analytes on polyurethane foam is most often applied. 

The last part of the book, Chapters 10—17, reports on different applications of polymers in the field of analytical chemistry sorption of organic compounds, Hke phenols, pesticides or caffeine, the use of polymeric materials for size-exclusion chromatography, for HPLC packing materials or as solid phase extraction sorbents. The examples cover a broad variety of chemical compounds, fike pesticides, pharmaceuticals, organic acids in different matrices, such as food, biological fluids, non-aqueous media, air and the use of hemosorbents in blood purification. 

Solid-phase extraction has been called digital chromatography because its chief use is to retain and then remove analytes of interest in an on-off fashion. Outside of conducting breakthrough studies, the purely frontal chromatographic form has little practical value in TEQA. The elution step, in which an eluent whose polarity is near to that of the analyte, removes all analytes and can be viewed in a manner similar to that done for the sorption step ... 

Extraction of pesticide residues from liquid samples can be performed using a solid sorbent material. Currently available sorbent extraction techniques include (1) solid-phase extraction (SPE), (2) solid-phase microextraction (SPME), and (3) stir-bar sorptive extraction (SBSE). In the case of solid samples, a liquid extraction of pesticide residues (transfer into a solution) usually precedes the sorption step thus, it should be considered rather as a clean-up than an extraction. Matrix solid-phase dispersion (MSPD) represents a unique SPE approach that combines extraction and clean-up of solid or semisolid food samples in one step. In MSPD, the sample is mixed with a sorbent (Florisil, Cig, Cg) that serves as a solid support in sample disruption and dispersion. The resulting mix is packed into a column from which the analytes are eluted while separated matrix components are retained by the sorbent. The main drawbacks of this approach comprise rather small sample sizes ( 0.5g) and a relatively high consumption of expensive sorbents. 

Rudzinski, W., Gierak, A., Leboda, R., and D browski, A. 1995. Studies of properties of complex carbon-silica adsorbents used in sorption-desorption processes (solid-phase extraction). Fresenius J. Anal. Chem. 352 667-672. 

A comprehensive overview of preconcentration techniques for uranium (VI) and thorium (IV) prior to analysis was published (Prasada Rao et al. 2006). The multitude of off-line techniques that were reviewed includes liquid-liquid extraction, liquid membranes, ion exchange, extraction chromatography, flotation, absorptive electrochemical accumulation, solid-phase extraction (SPE), and ion imprinting polymers. In addition, online preconcentration methods for uranium, thorium, and mixtures of the two are also briefly surveyed. This overview includes over 100 references and is a good source for finding a suitable preconcentration technique with regard to the enrichment factor, retention and sorption capacity, method validation, and types of real samples. The review article focused on samples in which the uranium was already in solution so that digestion procedures for solid samples were not discussed (Prasada Rao et al. 2006). 

Modern analytical techniques usually have sufficient sensitivity to determine the concentration of uranium in aqueous environmental samples and in most cases mass spectrometric techniques can also provide isotopic composition data. However, in some samples, especially where the precise content of minor uranium isotopes is required then preconcentration, separation, and purification can improve the accuracy of the measurement. Several methods have been developed for this purpose based on solid phase extraction (SPE), electro-analytical selective absorption techniques, liquid-extraction, ion-exchange and chromatographic columns, co-precipitation, and selective sorption. Other methods, like single-drop microextraction, are being developed and may serve for microanalysis (Jain and Verma 2011). Some of these techniques are discussed in the context of the specific sample preparation procedures throughout the book, so in this section only a few select methods will be discussed. 

Baker DR, Kasprzyk-Hordem B (2011) Multi-residue determinatimi of the sorption of illicit drugs and pharmaceuticals to wastewater suspended particulate matter using pressurized liquid extraction, solid phase extraction and liquid chromatography coupled with tandem mass spectrennetry. J Chromatogr A 1218 7901—7913... 

The efficiency of CD polymers as a solid phase extraction materials for anionic dyes has been investigated. The influence of pH, concentration, contact time and sodium chloride amount on their adsorption capacity has been evaluated. It was found that the addition of sodium chloride to aqueous solution results in higher efficiency of sorption by minimizing electrical charge on the surface of the polymer. 

Brombenztiazo (BBT) is known to be one of the best reagents for extraction-photometric determination of cadmium(II). The reagent also fonus complexes with Co(II), Cu(II), Fe(II), Ni(II), Zn(II). The aim of this work was to develop a solid-phase reagent on the base of BBT immobilized on silica gel for sorption-spectroscopic and visual test determination of Cadmium, and also for soi ption-atomic-adsoi ption determination of total heavy metals contents in natural waters. 

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