Au@AgNPs-based SERS for the simultaneous detection of carbendazim and thiabendazole residues in tobacco leaves

Abstract

Surface-enhanced Raman spectroscopy (SERS) is a promising technique for the rapid detection of trace pesticide residues because of its high sensitivity, fast response, and low cost. Nevertheless, the simultaneous label-free detection of multiple pesticide residues in complex matrices remains a challenge. In this work, a label-free SERS method based on Au@Ag core-shell nanoparticles (Au@AgNPs) was developed for the simultaneous detection of thiabendazole (TBZ) and carbendazim (CBZ) in tobacco leaves. Au@AgNPs with different silver shell thicknesses were synthesized by the seedmediated growth method, and R6G was used as a probe molecule to select the optimal silver shell thickness. The optimized Au@AgNPs were employed as SERS-active substrates for the identification of TBZ and CBZ based on their characteristic Raman peaks at 784 cm⁻¹ and 1227 cm⁻¹, respectively. The SERS intensities of TBZ and CBZ exhibited good linear correlations with concentration in the range of 1-10 mg/kg, with R² values of 0.985 and 0.991, respectively. The limits of detection for TBZ and CBZ in the tobacco leaf matrix were 0.26 mg/kg and 0.10 mg/kg, respectively. The recoveries ranged from 95.01% to 117.15% for CBZ and from 85.80% to 109.57% for TBZ. These results demonstrate that the proposed method enables the rapid simultaneous detection of TBZ and CBZ in tobacco leaves and provides a feasible and effective approach for the rapid screening of pesticide residues in tobacco leaves and related agricultural products.