Comparison of extraction techniques for polycyclic aromatic hydrocarbons from lichen biomonitors

Author(s): Leandri Van der Wat and Patricia B. C. Forbes
Department of Chemistry, University of Pretoria, Hatfield, South Africa

Published By: Environmental Science and Pollution Research

Issue: 26

Year of Publication: 2019


Abstract: Lichens are useful biomonitors for atmospheric polycyclic aromatic hydrocarbons (PAHs). Different sample preparation techniques were explored in this regard, including ultrasound-assisted solvent extraction, microwave-assisted extraction, Soxhlet, and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique. It was found that a QuEChERS technique using hexane:acetone (1:1, v/v), never reported before for application to lichens, provided the best recoveries of internal standards, the highest total peak area for all PAHs of interest, and %RSDs comparable with the other preparation techniques tested. The optimized sample preparation technique was found to be a comparatively fast method (45 min), with good recoveries (96%), using less solvents and minimal energy consumption. Strong matrix effects were found: both strong enhancement (for the lighter PAHs) and strong suppression (for the heavier PAHs). The use of matrix-matched standards is thus imperative for the accurate determination of PAH concentrations in the lichen samples.

Acknowledgment(s): Restek Corporation and Wirsam Scientific are
thanked for their support of this research.