Lexikon

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.