Carbon nanotubes-assisted solid-phase microextraction for the extraction of gasoline in fire debris samples

Gasoline is one of the most encountered ignitable liquids (IL) in fire debris analysis. The extraction of gasoline from fire debris samples presents challenges due to the complicated nature of multicomponent mixtures. This research work proposed a novel carbon nanotube-assisted solid phase microextraction (CNT-SPME) fiber coupled with gas chromatography and mass spectrometry (GC/MS) to determine gasoline residues for fire debris analysis. The CNT-SPME fiber was prepared by a sequential coating of polydopamine, epoxy, and CNTs on a stainless-steel wire. The extraction capabilities of the CNT-SPME fiber for gasoline and its major aromatic groups (xylenes, alkylbenzenes, indanes, and naphthalenes) from neat and spiked samples were promising, with linear dynamic ranges of 0.4-12.5 and 3.1-12.5 µg 20-mL^-1 headspace vial, respectively. The average relative standard deviations and accuracies for all concentration ranges in this work were lower than 15%. The relative recovery of the CNT-SPME fiber for all aromatic groups ranged from 28 ± 3% to 59 ± 2%. Additionally, the CNT-SPME fiber showed a higher selectivity for the naphthalenes group in gasoline, as indicated by the experimental outcome using a pulsed thermal desorption process of the extracts. We envision the nanomaterial-based SPME offers promising opportunities for extracting and detecting other ILs to support fire investigation.