One-pot synthesized AgNPs@capillary SERS substrate for on-site detection of acetamiprid and carbendazim residues in citrus peels

Pesticide residues pose serious threats to food safety and human health, highlighting the need for rapid and sensitive detection methods. Traditional techniques are often time-consuming and complex, whereas Surface-Enhanced Raman Spectroscopy (SERS) offers a fast and highly sensitive alternative. In this study, silver nanoparticles (AgNPs) were synthesized via a one-pot hydrothermal method using trisodium citrate (TSC) as a reducing agent and polyvinylpyrrolidone (PVP) as a capping agent. By optimizing PVP and TSC concentrations, a novel AgNPs@capillary SERS substrate was fabricated through in situ assembly of AgNPs onto the inner walls of glass capillaries. The substrate enabled rapid, on-site detection of pesticide residues, specifically the neonicotinoid acetamiprid (ACE) and benzimidazole fungicide carbendazim (CBZ). SERS measurements showed strong linear correlations for ACE (R² = 0.9713, 0.01–0.5 μg/mL) and CBZ (R² = 0.9566, 0.005–0.5 μg/mL). Importantly, the detection limits reached 2.28 × 10⁻³ μg/mL for ACE and 6.25 × 10⁻³ μg/mL for CBZ, demonstrating excellent sensitivity. This study confirms the effectiveness of the one-pot synthesized AgNPs@capillary SERS platform as a practical tool for trace-level pesticide monitoring in environmental and food safety contexts.