Centrifuge-less Emulsification Microextraction Using Effervescent CO₂ Tablet for On-site Extraction of PAHs in Water Samples Prior to GC–MS Detection

Abstract

For the first time, centrifuge-less emulsification microextraction using effervescent CO₂ tablet (EME-ECT) coupled with gas chromatography-mass spectrometry (GC–MS) is presented for the preconcentration and determination of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. In this method, after injection of a mixture of extraction and disperser solvents into the sample with volume of 90 mL, an effervescent tablet containing the effervescence precursors (sodium bicarbonate as carbon dioxide source and sodium dihydrogen phosphate as proton donor) was applied for phase separation. Thanks to the in situ generation of carbon dioxide, as a consequence of the effervescence reaction, the dispersed extraction solvent was collected at the surface of the aqueous sample and then was narrowed to the capillary part of a special home-made extraction cell for facile retrieval. The experimental variables, including volume of extraction and disperser solvents, ionic strength and weight of effervescent tablet, were investigated and optimized by a central composite design. Under the optimal conditions, the limits of detection were at the range of 0.01–0.1 µg L⁻¹ and preconcentration factors were varied between 134 and 406 for different PAHs. As can be seen here, there is no need for centrifugation or a special apparatus for the proposed emulsification microextraction method and it can easily be applied for the analysis of large volumes of samples. Taking these advantages to account, EME-ECT has the most promise for becoming a quick, simple and economical approach to reduce transportation costs after water sampling in the field.