Waxberry-like magnetic porous carbon composites prepared from a nickel-organic framework for solid-phase extraction of fluoroquinolones

A unique waxberry-like magnetic hierarchical porous carbon hybrid was synthesized from a nickel based metal–organic framework (Ni-MOF) which, on calcination, produces hierarchical Ni/NiO nanocrystals covered with graphitic carbon (GrC). The material was applied to magnetic solid phase extraction (MSPE) of trace levels of four fluoroquinolones (FQs) from environmental water samples. It is shown to exhibit superior extraction capability for four FQs, because the novel 3D morphology provides an enhanced surface area along with transport channels, while Ni and graphitic carbon as potential adsorption sites are ideal components. The material with inherent magnetism is reusable and displays superb recycling stability for the adsorption and desorption (by using alkaline methanol) of FQs after 6 cycles. The FQs were quantified by HPLC with UV detection, and the limits of detection (at an S/N ratio of 3) range between 7.9 and 57 ng·L−1. Recoveries from spiked environmental water samples are between 88.8 and 103.7%.