Construction of the SERS substrate of AgNPs modified with N-Acetyl-L-cysteine and ZnO for sensitive detection of acephate

A highly sensitive surface-enhanced Raman spectroscopy (SERS) method for the detection of acephate was established by using the substrate of silver nanoparticles (AgNPs) modified with N-acetyl-L-cysteine (NAC) and zinc oxide (ZnO). The Raman signal enhancement factor (EF) of acephate by the substrate of ZnO/NAC/AgNPs can be reached 4.95 × 10 6 . The ultraviolet-visible spectroscopy (UV-vis), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), zeta potential, Fourier transform infrared spectra (FT-IR) and thermogravimetric analysis (TGA) were used to characterize the substrate of ZnO/NAC/AgNPs. The mechanism of electromagnetic enhancement (EM) assisted by chemical enhancement (CM) was elucidated in detail. The optimal experimental conditions were selected. The interference experiments showed that this method had high selectivity in complex substrates. There was a good linear relationship between acephate concentration and SERS signal intensity in the range of 6.00 × 10 −9 mol L −1 – 8.00 × 10 −7 mol L –1 , and the linear equation was I SERS = 85.02 c + 24712.49 ( r = 0.9982, c : nmol L −1 ) with the limit of detection (LOD) was 3.40 nmol L –1 (3 σ / S ). The SERS method was successfully applied for the detection of acephate residues in vegetable samples, and the recovery was in the range of 95.3% – 104% ( n = 5).