Micro-extraction by Packed Sorbent

Drawbacks of the MEPS technique include the possibility of bubble formation and some difficulties connected to off-line arrangement as on-line coupling is not possible with every LC system. For off-line MEPS the speed of plunger movement is cmcial for the recovery of analytes. An excessively high speed of movement does not allow 

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Rani, S., Malik, A.K., Singh, B. Novel micro-extraction by packed sorbent procedure for the liquid chromatographic analysis of antiepileptic drugs in human plasma and urine. J. Sep. Sci. 35, 359-366 (2012)... 

This section discusses dispersive SPE, matrix solid phase dispersion, solid phase micro-extraction, micro-extraction by packed sorbent, stir-bar sorbent extraction, and the restricted-access materials. ... 

Micro-extraction by packed sorbent, miniaturized SPE sample preparation method using a packed syringe needle, and GC injection via liquid desorption in the GC injector. 

Some advances have been accomplished exploiting SIA and an additional peristaltic pump, in order to mix by confluence the sample and the disperser/extractant mixture. However, additional steps are required such as the need of a solid support for the retention/collection of the dispersed organic micro-droplets, and the re-elution of the retained microdroplets from the polytetrafluoroethylene (PTFE) support prior to detection. Other SIA systems have been proposed by using a conical tube and adding an auxiliary solvent to adjust the density of the extraction solvent when this is lighter than water density [17—19]. Other authors use micro columns packed with hydrophobic sorbent materials after extraction as phase separators requiring a second extraction [20—22]. 

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