Air assisted liquid-liquid microextraction

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Dispersive liquid-liquid microextraction (DLLME) is a consolidated technique in the treatment of liquid samples due to its rapidity and efficiency. In fact, the almost complete extraction of the analytes, with absolute recoveries near to 100%, can be achieved in a few minutes. In the classical DLLME approach a mixture of solvents, the disperser and extraction ones, is injected in the sample producing the efficient dispersion of the extractant which enhances the contact area with the sample. After dispersion, the extract is recovered by means of a centrifugation step.

Despite its usefulness, the classical approach presents some limitations. For example, the requirement of a disperser solvent in the mL range is not completely compatible with a green procedure, although the typical solvents are not too toxic. Moreover, the disperser solvent may participate in the analytes partition, especially for polar analytes, increasing the solubility of the analytes in the sample.

Air assisted liquid-liquid microextraction (AALLME), recently proposed by Farajzadeh and Afshar Mogaddam, substitute the use of a disperser solvent by an innovative procedure (1). A small volume of extractant is added to the sample and the mixture is sucked several times by a glass syringe producing an efficient dispersion of the solvent. After the extraction, the solvent is recovered by centrifugation. AALLME is compatible with simultaneous derivatization which increases the potential applicability of the technique (2).

In a recent development, Farajzadeh and Khoshmaram have proposed the use of solvents with density lower than that of water as solvents (3). The authors have developed a method for the extraction of triazole pesticides from water and different commodities, the target analytes being finally determined by gas chromatography with flame ionization detection. Remarkable enrichment factors, in the range of 713-808, are obtained with a simple and precise enough (relative standard deviation lower than 7%) procedure.

We strongly recommend these articles to our readers.

References:

(1) Air-assisted liquid–liquid microextraction method as a novel microextraction technique; Application in extraction and preconcentration of phthalate esters in aqueous sample followed by gas chromatography–flame ionization detection. Link to the article
(2) Simultaneous derivatization and air-assisted liquid–liquid microextraction of some aliphatic amines in different aqueous samples followed by gas chromatography-flame ionization detection. Link to the article
(3) Air-assisted liquid–liquid microextraction-gas chromatography-flame ionisation detection: A fast and simple method for the assessment of triazole pesticides residues in surface water, cucumber, tomato and grape juices samples. Link to the article


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