Solvent bar microextraction of emerging pollutants from drain water samples

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The efficiency of a given microextraction technique depends on both thermodynamic and kinetic aspects. The distribution constant defines the maximum extractable analyte whereas the kinetic establishes the rate at which this distribution takes place. Among the kinetic factors, the efficient diffusion of the target analytes from the bulk sample solution to the acceptor phase is a key aspect. This diffusion can be easily enhanced by an efficient stirring of the sample or the acceptor phase during the extraction.

Solvent bar microextraction (SBME), which was firstly presented by Jiang and Lee in 2004, (1) enhances the diffusion of the analytes through an efficient stirring of the acceptor phase. SBME uses a solvent immobilized in the lumen and pores of a polypropylene hollow fiber as extracting phase. Both ends of the hollow fiber are sealed and the resulting solvent bar is introduced in the sample where it moves free and randomly. After the extraction, the solvent bar is recovered and the extractant is finally analyzed by an appropriate instrumental technique.

Guo and Lee, in a recent article published in Journal of Chromatography A, have proposed a SBME procedure for the extraction of six residual pharmaceuticals (naproxen, ibuprofen, ketoprofen, propanolol, diclofenac and alprenolol) from drain water, being the analytes finally determined by gas chromatography/mass spectrometry (GC/MS).(2) Taking into account the polarity of the analytes, which is a shortcoming for GC/MS analysis, a derivatization step is required. Derivatization and extraction are performed at the same time by adding the derivatizing reagent to the extraction solvent. The SBME procedure provides better results than classic hollow-fiber liquid phase microextraction using the same extraction solvent, due to the enhanced contact with the sample. Moreover, SBME provides comparable results to those obtained by solid phase microextraction, although the SBME is faster (20 vs 60 min) and it avoids carry-over as a new solvent bar is used in each new extraction.

In the referenced article (2), the readers will find the optimization of the extraction procedure, the analytical characterization of the proposed method and a critical comparison with its main counterparts.

References

(1)Solvent Bar Microextraction. Link to the article
(2)One step solvent bar microextraction and derivatization followed by gas chromatography–mass spectrometry for the determination of pharmaceutically active compounds in drain water samples. Link to the article

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