Simultaneous detection of multiple pesticide residues in tobacco leaves using a PS@Ag SERS substrate and portable Raman spectrometer

Surface-enhanced Raman scattering (SERS) is a rapid, sensitive, and non-destructive technique for pesticide detection. However, most reported studies focus on single-analyte detection, and the simultaneous detection of multiple pesticide residues in complex matrices such as tobacco leaves remains challenging. In this study, we developed a portable SERS platform for the simultaneous detection of pendimethalin, propamocarb, and carbendazim using a polystyrene@silver (PS@Ag) core-shell substrate. The method enabled rapid detection (<15 min) with limits of detection (LODs) of 0.1 mg kg^-1 for carbendazim, 5 mg kg^-1 for pendimethalin, and 10 mg kg^-1 for propamocarb in individual analyte detection, which meets the European Union's maximum residue limits (MRLs). In ternary mixtures, the LODs were 1 mg kg^-1 for carbendazim, 5 mg kg^-1 for pendimethalin and 10 mg kg^-1 for propamocarb with strong linearity (<i>R</i>² = 0.97-0.98). The substrate exhibited uniform enhancement with relative standard deviations (RSDs) of 3.53% for pendimethalin, 7.76% for propamocarb, and 4.70% for carbendazim, and high sensitivity, achieving enhancement factors for all target pesticides (3.4 × 10¹ for pendimethalin, 3.7 × 10¹ for propamocarb, and 6.0 × 10³ for carbendazim). To the best of our knowledge, this is the first report to demonstrate that a PS@Ag SERS substrate combined with a portable Raman spectrometer serves as a highly reliable and promising tool for on-site monitoring of multiple pesticide residues in food safety and environmental applications.