Polymeric ionic liquid monolith for stir cake sorptive extraction

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Stir cake sorptive extraction (SCSE) was proposed in 2011 by researchers from the Xiamen University at China as an alternative to classic stir bar sorptive extraction.(1) The novel extraction technique is especially useful when monolithic polymers, characterized by their low mechanical stability, are employed as extracting phases. In SCSE a disk of monolithic material is introduced in a dedicated device in order to protect it from cracking due to the friction with the extraction vessel walls. The device also allows the stirring of the solution, thanks to a metallic wire, enhancing the analytes transference from the bulk solution to the extracting phase. In the first application, the efficient extraction of steroid hormones from milk was achieved using poly(vinylimidazole-divinylbenzene) monolithic with a low effect of the sample matrix (it was not required to remove fat and proteins).

In a recent article, accepted for publication in Journal of Chromatography A, the same research group extends the applicability of SCSE to the determination of inorganic ions in water samples using a polymeric ionic liquid (PIL) monolithic as extracting phase.(2) Since their proposal in 2010, PIL have attracted much attention as they present the exceptional properties of ionic liquids (good extractability towards different analytes and thermal stability, among others) in the solid state which is specially interesting for solid phase (micro)extraction approaches. While PILs have been extensively used for the extraction of organic analytes, in this case they are proposed for the extraction of inorganic anions such as: F-, Cl-, NO2-,Br-, NO3-, PO43- and SO42-. With this SCSE approach, the target analytes can be determined precisely with limits of detection as low as 0.11 µg/L.

Polymeric ionic liquid monolithic for stir cake sorptive extraction
In the original article, the readers will find the description of the PIL monolithic synthesis as well as its optimization process where the proportion of monomers and porogenic solvents are studied in depth. Moreover, they will find characterization of the monolithic by different analytical techniques, including infrared spectroscopy, scanning electron microscopy, elemental analysis and mercury intrusion porosimetry. In addition, the article describes the analytical charcaterization of the proposed method.


References:

(1) Novel extraction approach for liquid samples: Stir cake sorptive extraction using monolith. Link
(2) Preparation of a new polymeric ionic liquid-based monolith for stir cake sorptive extraction and its application in the extraction of inorganic anions. Link

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