Extraction of Polycyclic Aromatic Hydrocarbons from Aqueous Solution Using Agitation-Assisted Liquid-Liquid Microextraction with a Floating Organic Solvent Collected via a Pasteur Pipette

Abstract

A modification of a dispersive liquid-liquid microextraction (DLLME) procedure through the introduction a less dense binary-solvent mixture that floats on the surface of the aqueous solution for the extraction of polycyclic aromatic hydrocarbons from river water samples is presented in this study. The extracts were analyzed by gas chromatography coupled to mass spectrometry followed by partial validation and application of the method to real water samples collected near a dumpsite. This modified extraction was optimized for selected parameters which were deemed important and uses 50 µL of 25% tetrachloromethane in dodecane spiked into 1.5 mL aqueous solutions containing 10% NaCl. This technique yielded excellent solvent recovery as opposed to unmodified DLLME where solvent losses of up to 95% have been reported. Notwithstanding, the method demonstrated enrichment factors between 179 and 301, sufficient linearity (R² ≥ 0.9880), repeatability with %RSD 5.6 - 14.3%, n = 27, as well as low limits of detection (34 – 73 ng/L) except for only two compounds, benzo(b)fluoranthene (190 ng/L) and dibenz(a,h)anthracene (250 ng/L). The recoveries in spiked water samples ranged from 97 to 115%. This report presents yet another candidate in the pool of method applicable for analyses of PAHs from aqueous matrices.

Keywords:

• Polycyclic aromatic hydrocarbons
• agitation
• liquid-liquid microextraction
• floating organic solvent
• glass capillary
• binary mixture

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors gratefully acknowledge OPCW (Grant No. L/ICA/ICB/196770/15), National University of Lesotho (Grant No. P116-9008) and University of Botswana for supporting this work.