Rapid enrichment and determination of fishery drugs residue in fishes and shrimps by ZnO-Ag SERS substrate

Long-term adsorption saturation of plasmonic substrate and serious matrix interference are two challenges limiting on-site detection of aquatic products by surface-enhanced Raman scattering (SERS). Herein, an enrichment-sensing strategy was presented for rapid SERS analysis of nitrofurantoin and methylene blue in aquatic products by AgNPs decorated olive-shaped ZnO substrate. The substrate with an enhancement factor of 2.7 × 10 7 , achieved rapid enrichment and SERS sensing of nitrofurantoin and methylene blue in 5 min. The detection limits were 8.9 and 0.46 μg/L for nitrofurantoin and methylene blue, respectively. Signal uniformity was achieved with RSDs below 7.5 % ( n  = 31), and batch-to-batch stability showed RSDs below 9.8 % ( n  = 7). The substrate exhibited reusability for over 5 cycles and long-term stability over 7 weeks. The enhancement mechanisms were simulated using the finite-difference time-domain method and a charge-transfer model. The strategy was successfully applied for rapid SERS analysis of nitrofurantoin and methylene blue in aquatic products with recoveries of 91.6 %–113.2 % and RSDs of 0.5 %–7.8 % ( n  = 3).