Development of an Integrated EC-SPME-SERS Platform with the pAg-rGO-Au Substrate for Ultrasensitive Detection of Fenthion.

Surface-enhanced Raman scattering (SERS) is widely applied for ultrasensitive and label-free detection of molecules, but its potential is largely limited by complex matrix interference and the weak affinity between target molecules and the SERS substrate. To overcome these limitations, this study fabricates a pAg-rGO-Au substrate and develops an integrated platform combining electrochemistry (EC), solid-phase microextraction (SPME), and SERS. Leveraging the multifunctionality of pAg-rGO-Au (as a working electrode, SPME sorbent, and SERS substrate), the EC-SPME-SERS platform enables electro-enhanced adsorption and in situ detection of fenthion (FEN). Both experiments and theoretical simulations reveal that FEN adsorption on the pAg-rGO-Au substrate is achieved through the synergistic effects of chemical bonding and van der Waals forces. Furthermore, the applied potential of -0.8 V significantly enhances the van der Waals interactions between FEN and Au NPs, promoting the enrichment of FEN at SERS hotspots. This optimal potential leads to a 4.8-fold enhancement in SERS signal for FEN compared to conventional SPME-SERS detection. EC-SPME-SERS achieves a remarkably low limit of detection of 2.7 nM, representing a 30-fold improvement in sensitivity over SPME-SERS (82 nM). A satisfactory recovery rate (95.41%-105.46%) in real samples highlights the robust anti-interference capability of the EC-SPME-SERS method in complex matrices. These results underscore the potential of the EC-SPME-SERS platform as a powerful tool for food safety monitoring, paving the way for highly sensitive and accurate SERS-based detection.