SERS-Based Rapid Detection of Pesticide Residues on Apple Peels Using Commercial Formulations

This study explores a rapid method for detecting commercial pesticide mixtures, containing adjuvants, on a fruit’s surface. The approach integrates adhesive tape sampling with surface-enhanced Raman spectroscopy (SERS) to simultaneously analyse chlorpyrifos and cypermethrin from industrial pesticide cocktails. The optimal tape was chosen based on the highest signal-to-noise ratio and lowest background interference. The method achieved limits of detection (LODs) of 0.33 ppm [0.36µg/cm²] for chlorpyrifos and 0.5ppm [0.55µg/cm²] for cypermethrin, with limits of quantification (LOQs) of 1.1 and 1.65ppm, respectively, on apple peels. Enhancement factors reached 1.1×10⁶ for chlorpyrifos and 2.57×10⁵ for cypermethrin, with ~18% signal variability at the highest concentration. This approach demonstrates effective, repeatable SERS-based detection of pesticide residues from industrial mixtures with mixed constituents and stabilising adjuvants, as opposed to analytical standards, supporting field applicability.