Physical contraction strategy for large-scale fabrication of reduced graphene oxide-coated solid phase...

Polycyclic aromatic hydrocarbons (PAHs) pose severe ecological hazards and are widely distributed through both biological and anthropogenic processes, necessitating the development of a sensitive analytical method for their direct and quantitative monitoring in environmental samples. Due to the complexity of environmental water sample matrices and the trace concentrations of PAHs, a pre-concentration step is typically required before instrumental analysis. This study presents the development of a headspace-solid phase microextraction (HS-SPME) technique for the extraction and pre-concentration of seven common trace PAHs from environmental water samples.

A novel physical contraction method was applied for the first time to fabricate robust reduced graphene oxide (rGO)-coated fibers on a large scale. During the fabrication process, three-dimensional rGO was formed around a stainless steel wire (SSW) using ascorbic acid as a reducing agent in an aqueous medium. The coating was firmly fixed onto the SSW through the physical volume contraction of the wet rGO during the drying process. When coupled with capillary gas chromatography-mass spectrometry (GC/MS) in headspace mode, the as-fabricated fiber demonstrates exceptional extraction efficiencies for PAHs. This efficiency is attributed to the tree-bark-like structure and the π-electron conjugation systems present in rGO. Furthermore, the fiber exhibits remarkable stability, enduring over 150 extraction cycles without compromise, owing to the solvent and thermal resilience of rGO and the superior mechanical strength of SSW. For PAH analysis, the fiber provides a wide linear range of 1-100 ng/L, with detection limits between 0.1 and 0.3 ng/L. The method also achieves a relative standard deviation (RSD) below 6.4 % for a single fiber and 7.2 % across different fibers, along with recovery rates ranging from 85.2 % to 104.7 %.

The proposed strategy introduces an innovative approach to fabricating SPME fibers, addressing many limitations of existing methods for producing rGO-coated fibers, such as chemical bonding, dipping, and physical adhesion. This method is compatible with commonly used support materials, including metal wires and silica fibers, and allows for convenient adjustment of the length and thickness of the rGO coating. By providing a robust foundation for commercial applications, this study offers a valuable tool tailored for industrial use.