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solid phase extraction

a chromatographic technique used to prepare samples for subsequent analysis, an effective method to concentrate or isolate the non-volatile analytes. It is a kind of column chromatography. The extract is eluted through the column (cartridge) containing the preconditioned sorbent by applying vacuum. The substance of interest is retained on the column and all the interfering components are eluted or the interfering components are retained and the substance of interest is eluted. This sample preparation technique is suitable for any compounds. The low solvent need, no need of concentration by evaporation and in this way avoiding the concentration of the polluting components, cheap sorbents, saving time, no emulsion formation, enhanced selectivity and potential for automatization are the advantages of SPE over the traditional liquid/liquid extraction (LLE).

solid phase microextraction
chemical extraction performed with a fiber coated with an extracting phase (solid or liquid). The coated fibers (with 5-10 micrometer coating) are used to isolate and concentrate analytes into the coating material. In the case of volatile compounds the fiber is kept in the headspace, in the case of non-volatile analytes the fiber is kept in the liquid to reach the equilibrium. After extraction, the fibers are transferred, with the help of the syringe-like handling device, to analytical instruments for separation and quantification of the target analytes. Desorption is performed by heat (gas chromatography) or by elution (liquid chromatography). The concentration in the coating of the fiber is proportional with that in the sample. The extraction is fast, easy to be automated, simple, can be done without solvents, and detection limits can reach parts per trillion (ppt) levels for certain compounds.