Carboxylated carbon carbon nanospheres as solid-phase extraction adsorbents for the determination of perfluorinated compounds in water samples by liquid chromatography-tandem mass spectrometry

This work demonstrates the extraction potential of carboxylated carbon nanospheres (CNSs-COON) for solid-phase extraction of perfluoroalkyl acids (PFAAs) for the first time. Six PFAAs, including perfluorohexanesulfonate (PFHxS), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorooctanoic sulfonic (PFOS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), were quantitatively adsorbed on a CNSs-COOH-packed cartridge; then, the PFAAs retained on the adsorbent were quantitatively eluted with an optimized volume of acetone (pH = 10). Finally, the desorbed PFAAs were determined by liquid chromatography-tandem mass spectrometry. Important relevant factors, such as the eluant and its volume, sample pH, amount of CNSs-COOH, sample flow rate and sample volume were optimized in detail. Under the optimized conditions, low limits of detection (0.01-1.2 ng L-1), wide linear range (0.50-200 ng L-1) and good repeatability (2.4-5.1%) and good reproducibility (3.7-8.8%) were obtained. The proposed method was applied to analyze the six PFAAs in real environmental water samples, and satisfactory results were achieved. All of these results showed that CNSs-COOH will be a good choice for the pre-concentration and analysis of target PFAAs at trace levels in environmental water samples in the future.