Abstract: Fe3O4@SiO2@silver nanoparticles (AgNPs) were synthesized by a facile seed-mediated method and used as a surface enhanced Raman scattering (SERS) substrate to detect the content of the trace additive ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) in prepackaged dried rice noodles. Fe3O4@SiO2@AgNPs were characterized by transmission electron microscopy, X-ray energy spectroscopy, X-ray diffraction spectroscopy, infrared spectroscopy, and SERS spectroscopy. The results showed that Fe3O4@SiO2@AgNPs were a magnetic substrate with a core-shell structure, and a diameter of about 660 nm. The minimum detectable concentration of rhodamine 6G (R6G) solution was measured to be 1 × 10-9 mol/L and the enhancement factor was 4.27 × 108. The limit of detection (LOD) of EDTA-2Na solution using Fe3O4@SiO2@AgNPs was 1.75 × 10-6 mg/mL. Good linearity was observed between the SERS intensity of the characteristic peak at 1 625 cm-1 and the logarithmatic concentration of EDTA-2Na with a correlation coefficient (R2) of 0.994. The LOD was 0.1 mg/kg for EDTA-2Na in prepackaged dried rice noodles, and the recoveries for spiked samples were 96.50%–104.67% with relative standard deviation (RSD) of 1.2%–4.2%. Accordingly, this method can accurately, sensitively and rapidly detect whether EDTA-2Na is added in excess in prepackaged dried rice noodles.

Key words: surface enhanced Raman scattering; prepackaged dried rice noodles; Liuzhou river snail rice noodles; ethylenediaminetetraacetic acid disodium salt; Fe3O4@SiO2@AgNPs