3.1.4 Effect of desorption volume
To evaluate the effect of desorption volume on the PAH extraction efficiency, the desorption volumes were varied from 0.1 to 0.6 mL. The desorption solution was diluted to 0.6 mL prior to detection with HPLC. The results in Fig. S2 demonstrate that the highest peak area was achieved with 0.4 mL of the desorption solvent. Thus, 0.4 mL was selected as the most appropriate desorption volume.