• Spectroscopy and Spectral Analysis
  • Vol. 40, Issue 1, 305 (2020)
YI Zhen-fei1、*, LIU Chun-yu1、2, XIN Min-si1, KUANG Shang-qi1, ZHOU Cheng-cheng1, YAO Zhi-hai1、2, and CAI Hong-xing1
Author Affiliations
  • 1[in Chinese]
  • 2[in Chinese]
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    DOI: 10.3964/j.issn.1000-0593(2020)01-0305-05 Cite this Article
    YI Zhen-fei, LIU Chun-yu, XIN Min-si, KUANG Shang-qi, ZHOU Cheng-cheng, YAO Zhi-hai, CAI Hong-xing. Study of Density Functional Theory on Surface Enhanced Raman Spectroscopy of Fipronil[J]. Spectroscopy and Spectral Analysis, 2020, 40(1): 305 Copy Citation Text show less

    Abstract

    At the beginning of August 2017, Netherlands reported that a wide range of eggs were contaminated with the insecticide fipronil. In this study, the Raman spectroscopy was used to solve the problem of fipronil detection. The stable configuration and all vibration modes of the molecule were obtained after the geometrical structure optimization and frequency calculation, and the theoretical Raman Scattering spectroscopy of the stable configuration of fipronil was also calculated. Normal Raman spectroscopy and surface enhanced Raman spectroscopy of fipronil were collected by HORIBA’s T64000 grating confocal micro-Raman spectroscopy and Ag/Cu nano-substrate. The strong peaks appeared at 211, 308, 350, 867, 1 323, 1 432 cm-1, and the sub-strong peak appeared at 254, 407, 443, 463, 511, 607, 646, 712, 800, 1 065, 1 639 cm-1. The results show that the theoretically calculated vibration frequency agrees well with the experimental measurements at all strong peaks and most sub-strong peaks. The vibration modes corresponding to the frequencies of the fipronil molecule in the range of 200~2 000 cm-1 were assigned. The six strong peaks arranged from small to large were judged to be 21H-22H torsional vibration, 10F-11F deformation vibration, 21H-22H out-of-plane torsional vibration, 15N-22H twisting vibration, 6C stretching vibration and 21H in-plane torsional vibration, benzene ring breathing vibration and stretching vibration of 9C, 7H-8H in-plane torsional vibration. It was found that the surface-enhanced Raman spectrum has a slight frequency shift with respect to the Raman spectrum. The peaks at 211, 867, 1400, and 1 432 cm-1 in the surface-enhanced Raman spectroscopy were selectively enhanced. According to the selection rule of surface-enhanced Raman spectroscopy, it is interpreted as the atom corresponding to the relevant vibration peak and the surface of the silver substrate may be in a nearly vertical state and may be stick to the silver surface. In the next step, fipronil will be planned to be mixed into eggs, and the identification of fipronil in different concentrations in eggs will be carried out. The results of the study can provide a theoretical basis for the Raman spectroscopy of fipronil, which will promote the rapid detection and on-line detection of fipronil residues in food and agricultural products. Raman spectroscopy will be used as a supplement to conventional chemical detection methods.
    YI Zhen-fei, LIU Chun-yu, XIN Min-si, KUANG Shang-qi, ZHOU Cheng-cheng, YAO Zhi-hai, CAI Hong-xing. Study of Density Functional Theory on Surface Enhanced Raman Spectroscopy of Fipronil[J]. Spectroscopy and Spectral Analysis, 2020, 40(1): 305
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