Enhancing glyphosate detection in rice by SERS: controlled aggregation of silver nanoparticles and carbon disulfide-mediated signal amplification.

A highly sensitive and rapid surface-enhanced Raman spectroscopy (SERS) method was developed for glyphosate (GPH) detection in rice by combining carbon disulfide (CS2)-mediated derivatization with an optimized silver nanoparticle (AgNP) aggregation strategy. GPH was converted into a SERS-active thiazole derivative through pH-controlled reactions. An adsorption-first strategy (analyte pre-adsorption before aggregation) enhanced signals by 64.78 % at 1 min and maintained 11.83 % higher intensity after 6 min versus conventional aggregation-first methods, due to optimized hotspot positioning. The method achieved a detection limit of 0.13 μmol/L (signal-to-noise ratio = 3), below European Union regulatory limits, with excellent reproducibility (RSD = 8.39 %), high selectivity against amino acid interferents, and high time efficient (22 min total analysis). Moreover, spike-recovery tests in rice yielded 80.82 % - 129.62 % recovery, providing a robust platform for detection of trace GPH in complex food matrices. Consequently, this work establishes a time-efficient and cost-effective alternative to conventional chromatography, which facilitates rapid on-site monitoring.