Aerosol phase extraction for a better and greener dispersion

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The efficient dispersion of the extracting phase into the sample is a useful strategy to enhance the kinetic of a given extraction technique. The dispersion enhances the contact area between phases making easier the transference of the target analytes across the interface. Dispersive procedures have been exploited both in the liquid and solid (micro)extraction techniques, being dispersive liquid-liquid microextraction (DLLME) a preeminent example. In DLLME, the dispersion of the extractant can be assisted chemically, by using a disperser solvent or surfactants, or applying an external energy source like ultrasounds.

In a recent article, accepted for publication in Talanta, aerosol phase extraction (APE) has been proposed for the first time as an alternative to these conventional approaches (1). In APE the sample is nebulized by an inert gas into the extracting phase in the form of very small drops. APE presents two very positive aspects which must be highlighted. On the one hand, the small drop sizes (in the µm range) make the extraction 5-6 times faster than classic liquid-liquid extraction. On the other hand, the dispersion is achieved by an inert gas which does not influence the partitioning of the target analytes between the involved phases. The latter aspect is quite interesting for the extraction of moderate polar compounds which may be problematic to extract in conventional DLLME as the disperser solvent (usually methanol or acetone) enhances their solubility into the aqueous sample.

This novel method has been applied to the extraction of molybdenum from sea water samples using organophosphorus chelating agents dissolved in n-hexane as extracting medium. The extracted analyte is finally analyzed by means of Inductively Coupled Plasma Atomic Emission Spectrometry. Good enrichment factors (ca. 12) and precision levels (relative standard deviation of 3%) are achieved with APE approach.

For more detailed information, including the description of the extraction manifold and the optimization process, readers are referred to the article.

References:

(1) Development of a new aerosol phase extraction method for metal determination through inductively coupled plasma atomic emission spectrometry. Link

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