Simultaneous Detection of Two Neonicotinoid Pesticides in Tea by Surface-enhanced Raman Spectroscopy

Abstract:

[Objective] The aim of the study is to establish a method for the simultaneous detection of residues of two neonicotinoid pesticides (thiacloprid and acetamiprid) in tea. [Method] Firstly, the theoretical Raman spectra of thiacloprid and acetamiprid were calculated with the Gaussian, and the chemical groups corresponding to the peaks of the two pesticides were determined by comparison with the conventional Raman spectra, with Raman peaks at 585 cm^-1 and 626 cm^-1 as the characteristic peaks, respectively. Silver-coated gold nanoparticles (Au@AgNPs) were further prepared as the enhanced substrate for surface-enhanced Raman spectroscopy (SERS). The standard curves for simultaneous detection of thiacloprid and acetamiprid were established. [Result] The optimal coagulant was 1.0 mol/L Na₂SO₄. The limits of detection of thiacloprid and acetamiprid in tea samples were 0.5 mg/kg and 1.0 mg/kg, respectively, which were lower than the residue limit in tea that was specified in the national standard. The recovery rates of thiacloprid and acetamiprid were within 85.0%~106.9%, which met the requirements of the detection method. [Conclusion] The established method achieves the simultaneous detection of thiacloprid and acetamiprid in tea.