Supercritical fluid extraction with carbon nanotubes as a solid collection trap for the analysis of polycyclic aromatic hydrocarbons and their derivatives

A supercritical fluid extraction (SFE) method with an online solid collection trap has been developed for the quantitative analysis of 16 polycyclic aromatic hydrocarbons (PAHs) and 15 typical PAH derivatives in solid matrix. Compared with liquid trapping and C18 solid-phase trapping, multi-walled carbon nanotubes (CNTs) were proved to be the most efficient trapping sorbent for the collection of PAHs and their nitro-, oxy- and alkyl-derivatives. The proposed extraction-collection procedure was systematically optimized in terms of pressure, temperature, extraction time, trapping materials, supercritical fluid flow rate, co-solvent type, and co-solvent percentage, taking into account the interaction between these variables. The whole extraction process could be completed in 15 min followed by GC-MS analysis. Quantitative recoveries of PAHs and their derivatives from spiked soil samples (50 ng g−1) were obtained in the range of 62.9-111.8% with the precisions (RSD, intra-day) ranged from 1.9% to 13.7%. The developed SFE method with online CNTs trapping followed by GC-MS analysis has been demonstrated to be an efficient way for quantitative analysis of trace-level PAHs and their nitro-, oxy-, and alkyl-derivatives in soil samples.