Graphenized pencil lead fiber: facile preparation and application in solid-phase microextraction

Graphenized pencil lead fiber was facilely prepared by in situ chemical exfoliation of graphite in pencil lead fiber to few-layered graphene sheets via a one-pot, one-step pressurized oxidation reaction for the first time. This new fiber was characterized and demonstrated to be a highly efficient but low-cost solid-phase microextraction (SPME) fiber. The extraction performance of the fiber was evaluated with four bisphenol analogs [bisphenol A (BPA), bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA)] as model analytes in direct SPME mode. Unlike commercially available fibers, the graphenized pencil lead fiber showed an excellent chemical stability in highly saline, acidic, alkaline and organic conditions due to its coating-free configuration. The fiber also showed a very long lifespan. Furthermore, high extraction efficiency and good selectivity for the analytes with a wide polarity range could be obtained due to the exceptional properties of graphene. The detection limits (LODs) for the analytes were in the range of 1.1-25ng/L. The fiber was successfully applied in the analysis of tap water and effluent samples from a waste water treatment plant with spike recoveries ranging from 68.5 to 105.1%. Therefore, the graphenized pencil lead fiber provides a high performance, cheap, robust, and reliable tool for SPME.