Organic components from solid matrices

Theoretical and applied aspects of microwave heating, as well as the advantages of its application are discussed for the individual analytical processes and also for the sample preparation procedures. Special attention is paid to the various preconcentration techniques, in part, sorption and extraction. Improvement of microwave-assisted solution preconcentration is shown on the example of separation of noble metals from matrix components by complexing sorbents. Advantages of microwave-assisted extraction and principles of choice of appropriate solvent are considered for the extraction of organic contaminants from solutions and solid samples by alcohols and room-temperature ionic liquids (RTILs). 

A significant advantage of this bulk micellar extraction technique is that once the initial extraction from the solid matrix has been performed, the organic components) now present in the extractant micellar solution can be further enriched and preconcentrated prior to final quantitation... 

Sample preparation represents a formidable challenge in the chemical analysis of the real-world samples. Not only is the majority of total analysis time spent in sample preparation, but also it is the most error-prone, least glamorous, and the most labor-intensive task in the laboratory. The components to be separated from the matrix are usually taken up with an auxiliary substance such as a carrier gas, an organic solvent, or an adsorbent. These separation processes can be regarded as extraction procedures (i.e., liquid-liquid extraction, liquid-solid extraction, Soxhlet extraction, solid-phase extraction, supercritical fluid extraction, solid-phase microextraction, etc.). 

Soil is composed of a heterogeneous mixture of solid, gaseous, and aqueous phases, the relative proportions of which can vary both spatially and temporally. The solid matrix consists of an intimate mixture of inorganic (primarily weathering products) and organic (products of biological decomposition) components. The proportion of total soil porosity occupied by water may vary from very low values up to 100% in a fully saturated soil. Soils typically develop a distinctive vertical zonation as a consequence of selective mineral dissolution coupled with... 

On-line combination of extraction system suitable for sample pre-treatment of solid samples is much more complex than for water samples. The main reason for this is that more exhaustive methods are required for efficient extraction of target analytes from a solid matrix, and this in practice means that the extracts typically contain high amount of co-extracted matrix components, that should not be transferred to a chromatographic system. Moreover, relatively high volumes of organic solvents are required for efficient extraction, making the on-line combination more challenging [156]. 

Many of the analytes of interest for solid phase chemical reference materials are the same as those in seawater, but the need for and the preparation of reference materials for suspended particulate matter and sediments is quite different. The low concentrations of many seawater species and the presence of the salt matrix create particular difficulties for seawater analyses. However while sediments frequently have higher component concentrations than seawater, they also have more complicated matrices that may require unique analytical methods. A number of particulate inorganic and organic materials are employed as paleoceano-graphic proxies, tracers of terrestrial and marine input to the sea, measures of carbon export from the surface waters to the deep sea, and tracers of food-web processes. Some of the most important analytes are discussed below as they relate to important oceanographic research questions. 

Appropriate SPE sorbent selection is critical to obtaining efficient SPE recovery of semivolatile organics from liquids. Henry [58] notes that an SPE sorbent must be able to sorb rapidly and reproducibly, defined quantities of sample components of interest. Fritz [73] states that successful SPE has two major requirements (1) a high, reproducible percentage of the analytical solutes must be taken up by the solid extractant and (2) the solutes must then be easily and completely eluted from the solid particles. The sorption process must be reversible. In addition to reversible sorption, SPE sorbents should be porous with large surface areas, be free of leachable impurities, exhibit stability toward the sample matrix and the elution solvents, and have good surface contact with the sample solution [68,73],... 

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