Helical multi-walled carbon nanotube-coated fibers for SPME determination of polycyclic aromatic hydrocarbons at ultra-trace levels in ice and snow samples

Polycyclic Aromatic Hydrocarbons (PAHs) detected in polar environment are recognized tracers of anthro- pogenic pollution. High sensitivity and selectivity are required for their analysis in ice and snow samples due to the presence at ultra-trace levels. In this study a solid-phase microextraction (SPME) gas chromatography-mass spectrometry (GC-MS) method for simultaneous determination of the 16 US-EPA priority pollutant PAHs in polar snow and ice samples was developed and validated. Helical multiwalled carbon nanotubes (HMWCNTs) were proposed for the first time as novel SPME coating. For optimization purposes a Central Composite Design and the multicriteria method of the desirability functions were applied to investigate the influence of extraction parameters, i.e. time and temperature as main factors. The optimal values were 68 °C for the extraction temperature and 60 min for the extraction time. The developed SPME-GC-MS method exhibited detection limits of 16 PAHs in the 0.1–1.2 ng/L range, a repeatability and an intermediate precision within 15% and 22% relative standard deviation, respectively, and good recovery rates in the 93.7 ( ±0.1)–119.7 ( ±0.2)% range for real spiked water sample, showing better analytical performance compared to commercial PDMS fibers. Enrichment factors in the 2670 ( ±290)–142120 ( ±580) range were calculated and a long fiber shelf-life with the possibility to reuse the fiber more than 200 times was achieved. Finally, the proposed method was successfully applied to the determination of PAHs in surface snow sam- ples collected in April 2019 at Ny- ̊Alesund, Svalbard. Its application to the detection of PAHs in samples collected during monitoring campaigns in the polar regions is expected in the near future