Continuous-flow microextraction

Another promising aspect of SME development has been directed toward achieving the continuous flow of an aqueous sample phase to a seemingly immobilized organic solvent drop, permitting the direct and continuous interaction of the drop with a fresh sample. The technique was called continuous-flow microextraction (CFME).11 12 In CFME, a polyetheretherketone (PEEK) tube is used as a holder for both the extraction solvent drop and the sample delivery supply. The drop (3 pL) is introduced into the PEEK tube via a valve and is pushed by the sample aliquot inside the tube until it reaches the tube outlet, where it remains (a little off-center of the tube) as a solvent drop. Then, the sample volume (typically 3 mL) is pumped continuously (from the PEEK tube) around the 

Few review articles have been published on microextraction procedures based on the use of a liquid-phase extractant.1314 One drawback of drop-based microextraction procedures is drop vulnerability this relates to its instability and potential dislodgement, which could be caused by sample complexity, a long extraction time, and a fast stirring speed. As a result, precision will often suffer significantly. 

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Liu, W. and H.K. Lee. 2000. Continuous-flow microextraction exceeding 1000-fold concentration of dilute analytes. Anal. Chem. 72 4462-4467. 

He, Y. and H.K. Lee. 2006. Continuous flow microextraction combined with high-performance liquid chromatography for the analysis of pesticides in natural waters. J. Chromatogr. A 1122 7-12. 

Li, Y., T. Zhang, and P. Liang. 2005. Application of continuous-flow liquid-phase microextraction to the analysis of volatile halohydrocarbons in water. Anal. Chim. Acta 536 245-247. 

Note SLM, supported liquid membrane (aq/org/aq) MMLLE, microporous membrane liquid-liquid extraction (aq/org) PME, polymer membrane extraction (aq/polymer/org) MESI, membrane extraction with sorbent interface (aq (or gas)/polymer/gas/sorbent) CFLME, continuous flow liquid membrane extraction (aq/org (in flow)/aq) LPME2, two-phase liquid phase microextraction in hoUow fibers (aq/org) LPME3, three-phase liquid phase microextraction in hollow fibers (aq/org/aq). 

Larsson N, Petersson E, Rylander M, Jonsson jA. Continuous flow hollow fiber liquid-phase microextraction and monitoring of NSAID pharmaceuticals in a sewage treatment plant effluent. Anal Methods 2009 1 59-67. 

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