{'fraction_non_alphanumeric': 0.035188739603326934, 'fraction_numerical': 0.014075495841330775, 'mean_word_length': 5.331983805668016, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Graphene-based metal and nitrogen-doped carbon composites as adsorbents for highly sensitive solid phase microextraction of polycyclic aromatic hydrocarbons.

Herein, a graphene-based metal and nitrogen-doped carbon (GNC-Co) composite, derived from zeolite imidazolate framework-67 (ZIF-67)-graphene oxide composites, was successfully developed and applied as an excellent fiber coating for solid phase microextraction (SPME) with enhanced performance. The fabricated carbon has a hierarchically micro/mesoporous structure with a high specific surface area of 123 m2 g-1. The study found that pyrolytic graphene (G) has good adsorption properties for anthracene, phenanthrene, fluoranthene and pyrene, while pyrolytic ZIF-67 (NC-Co) has good adsorption properties for naphthalene, acenaphthylene, acenaphthylene and fluorene. Combined with the advantage of G and NC-Co, the synthesized composite GNC-Co enabled the integration of the unique properties of these two fascinating materials and proved to show better performance in the extraction of all polycyclic aromatic hydrocarbons (PAHs). Compared to the commercial PDMS fiber, the self-made fiber achieved GC responses about 2-9 times as high as those obtained by the commercial 30 μm PDMS fiber. Furthermore, the self-made fiber obtained low detection limits in the range of 0.01-0.74 ng L-1 and wide linearity under the optimized extraction conditions. Finally, the GNC-Co coated fiber was successfully used for the detection of PAHs in real river water samples, which proved the applicability of the method.