Electrochemical fabrication of two-dimensional copper oxide nanosheets on stainless steel as a fiber coating for highly sensitive solid-phase microextraction of ultraviolet filters

A novel two-dimensional copper oxide (CuO) nanosheet coated fiber was directly fabricated on the surface of a piece of etched stainless steel wire using bulk electrolysis with coulometry (BE) for solid-phase microextraction (SPME). The field-emission scanning electron micrograph showed that the CuO nanosheet coated fiber possessed uniform nanostructures with a size of about 200 nm and a thickness of 30-45 nm. The fabricated CuO coated fiber was investigated for concentration and determination of trace phthalate esters (PAEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and ultraviolet (UV) filters coupled to high-performance liquid chromatography with UV detection (HPLC-UV). It was found that the fiber exhibited better extraction performance for UV filters. The main affecting conditions were investigated and optimized for SPME performance. Under the optimized extraction conditions, the proposed method showed good linearity between 0.10 and 400 g L-1 with the corresponding coefficients in the range of 0.9950-0.9977. The limits of detection ranged from 0.025 to 0.051 g L-1. The relative standard deviation for fiber-to-fiber reproducibility of five fabricated fibers was less than 8.3%. The proposed SPME-HPLC-UV method was successfully applied for the concentration and determination of trace UV filters in the Yellow River and wastewater with recoveries from 94.0% to 104.3%.