In-vial membrane assisted liquid-liquid microextraction

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Membranes can be used for different purposes in Analytical Chemistry. In the extraction context, they permit the development of several liquid-liquid extraction techniques such as dialysis, osmosis, among others. Also, they can provide an additional enhancement of the selectivity by the direct selection of the pore size. They are also commercialized in different formats (planar, tubular) and polarities in such a way that they can be applied to almost any analyte-sample binomial.

In liquid phase microextraction, membranes have been used under the 2 phases and 3 phases formats depending on the number, nature and role played by the different liquid phases involved. In order to favor the kinetic of the whole process the continuous agitation of the system is recommended to accelerate the diffusive transport of the target compounds in both the donor and acceptor phases reducing the thickness of the diffusion layer near the membrane.

Prof. Dr March and Prof. Dr. Cerdá have recently proposed an innovative approach that they called “in vial membrane assisted liquid-liquid microextraction”. The basic configuration consists of a 200 mL microvial sealed with a piece of a PTFE membrane of given dimensions. Before sealing, it was filled with the organic acceptor phase. The microvial was then placed inside a 50 mL glass tube which contains the sample. The system is screwed with a stopped maintained under continuous agitation until extraction is completed. The unit was evaluated using the determination of esters of phthalic acid in alcoholic beverages as model analytical problem. The main advantages of the proposed method are that the samples can be automatically processed and the chromatographic analysis only requires the replacement of the membrane of the microvial by a conventional septum. As the unit is fully compatible with the commercial autosampler, the chromatographic analysis is also automated.

We hope this excerpt will encourage our readers to go through the whole article to find out more specific information about this novel microextraction approach coming from the Balearic Islands. Enjoy it!!

Reference:
An innovative arrangement for in-vial membrane-assisted liquid-liquid microextraction: application to the determination of esters of phthalic acid in alcoholic beverages by gas chromatography-mass spectrometry. Link to the article


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